0001463101-21-000016 | 10-K | XBRL Viewer

Print Document View Excel Document

COVER PAGE - USD ($) $ in Billions	12 Months Ended
COVER PAGE - USD ($) $ in Billions	Dec. 31, 2020	Feb. 08, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-35480
Entity Incorporation, State	DE
Entity Registrant Name	Enphase Energy, Inc.
Entity Tax Identification Number	20-4645388
Entity Address, Address Line One	47281 Bayside Parkway
Entity Address, City or Town	Fremont
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94538
City Area Code	877
Local Phone Number	774-7000
Title of 12(b) Security	Common Stock, $0.00001 par value per share
Trading Symbol	ENPH
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 4.0
Entity Common Stock, Shares Outstanding		129,021,311
Documents Incorporated by Reference	Portions of the registrant’s Proxy Statement for the 2021 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission within 120 days after the end of the registrant’s fiscal year ended December 31, 2020 are incorporated by reference into Part III of this Annual Report on Form 10-K
Entity Central Index Key	0001463101
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY

CONSOLIDATED BALANCE SHEETS - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 679,379,000	$ 251,409,000
Restricted cash	0	44,700,000
Accounts receivable, net of allowances of $462 and $564 at December 31, 2020 and December 31, 2019, respectively	182,165,000	145,413,000
Inventory	41,764,000	32,056,000
Prepaid expenses and other assets	29,756,000	26,079,000
Total current assets	933,064,000	499,657,000
Property and equipment, net	42,985,000	28,936,000
Operating lease, right of use asset, net	17,683,000	10,117,000
Intangible assets, net	28,808,000	30,579,000
Goodwill	24,783,000	24,783,000
Other assets	59,875,000	44,620,000
Deferred tax assets, net	92,904,000	74,531,000
Total assets	1,200,102,000	713,223,000
Current liabilities:
Accounts payable	72,609,000	57,474,000
Accrued liabilities	76,542,000	47,092,000
Deferred revenues, current	47,665,000	81,783,000
Warranty obligations, current (includes $8,267 and $6,794 measured at fair value at December 31, 2020 and December 31, 2019, respectively)	11,260,000	10,078,000
Debt, current	325,967,000	2,884,000
Total current liabilities	534,043,000	199,311,000
Long-term liabilities:
Deferred revenues, noncurrent	125,473,000	100,204,000
Warranty obligations, noncurrent (includes $20,469 and $13,012 measured at fair value at December 31, 2020 and December 31, 2019, respectively)	34,653,000	27,020,000
Other liabilities	17,042,000	11,817,000
Debt, noncurrent	4,898,000	102,659,000
Total liabilities	716,109,000	441,011,000
Commitments and contingencies (Note 12)
Stockholders’ equity:
Common stock, $0.00001 par value, 200,000 shares and 150,000 shares authorized; and 128,962 shares and 123,109 shares issued and outstanding at December 31, 2020 and December 31, 2019, respectively	1,000	1,000
Additional paid-in capital	534,744,000	458,315,000
Accumulated deficit	(51,186,000)	(185,181,000)
Accumulated other comprehensive income (loss)	434,000	(923,000)
Total stockholders’ equity	483,993,000	272,212,000
Total liabilities and stockholders’ equity	$ 1,200,102,000	$ 713,223,000

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Accounts Receivable, Allowance for Credit Loss, Current	$ 462	$ 564
Product warranty, measured at fair value, current	8,267	6,794
Product warranty, measured at fair value, noncurrent	$ 20,469	$ 13,012
Common stock, par value (in usd per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	200,000,000	150,000,000
Common stock, shares issued (in shares)	128,962,000	123,109,000
Common stock, shares outstanding (in shares)	128,962,000	123,109,000

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net revenues	$ 774,425	$ 624,333	$ 316,159
Cost of revenues	428,444	403,088	221,714
Gross profit	345,981	221,245	94,445
Operating expenses:
Research and development	55,921	40,381	32,587
Sales and marketing	52,927	36,728	27,047
General and administrative	50,694	38,808	29,086
Restructuring charges	0	2,599	4,129
Total operating expenses	159,542	118,516	92,849
Income from operations	186,439	102,729	1,596
Other expense, net
Interest income	2,156	2,513	1,058
Interest expense	(21,001)	(9,691)	(10,693)
Other expense, net	(3,836)	(5,437)	(2,190)
Change in fair value of derivatives	(44,348)	0	0
Total other expense, net	(67,029)	(12,615)	(11,825)
Income (loss) before income taxes	119,410	90,114	(10,229)
Income tax benefit (provision)	14,585	71,034	(1,398)
Net income (loss)	$ 133,995	$ 161,148	$ (11,627)
Net income (loss) per share:
Basic (in USD per share)	$ 1.07	$ 1.38	$ (0.12)
Diluted (in USD per share)	$ 0.95	$ 1.23	$ (0.12)
Shares used in per share calculation:
Basic (in shares)	125,561	116,713	99,619
Diluted (in shares)	141,918	131,644	99,619

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 133,995	$ 161,148	$ (11,627)
Other comprehensive income (loss):
Foreign currency translation adjustments	1,357	(1,665)	1,398
Comprehensive income (loss)	$ 135,352	$ 159,483	$ (10,229)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794

+ Details

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Additional Paid-In Capital Cumulative Effect, Period of Adoption, Adjustment	Accumulated Income (Deficit)	Accumulated Income (Deficit) Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)
Balance, beginning of period (in shares) at Dec. 31, 2017			85,914
Balance, beginning of period at Dec. 31, 2017	$ (9,126)	$ (38,948)	$ 1	$ 287,256		$ (295,727)	$ (38,948)	$ (656)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201807Member
Issuance of common stock from exercise of equity awards and employee stock purchase plan (in shares)			3,185
Issuance of common stock from exercise of equity awards and employee stock purchase plan	$ 2,806			2,806
Issuance of common stock, net of offering costs (shares)			9,524
Issuance of common stock, net of offering costs	19,766			19,766
Issuance of common stock related to acquisition (shares)			7,500
Issuance of common stock related to acquisition	32,319			32,319
Exercise of warrants (shares)			912
Stock-based compensation	11,188			11,188
Net income (loss)	(11,627)					(11,627)
Foreign currency translation adjustments	1,398							1,398
Balance, ending of period (in shares) at Dec. 31, 2018			107,035
Balance, end of period at Dec. 31, 2018	7,776	$ 0	$ 1	353,335	$ 27	(346,302)	$ (27)	742
Issuance of common stock from exercise of equity awards and employee stock purchase plan (in shares)			5,273
Issuance of common stock from exercise of equity awards and employee stock purchase plan	4,985			4,985
Payment of withholding taxes related to net share settlement of equity awards	(8,198)			(8,198)
Conversion of convertible notes due 2023, net (in shares)			10,801
Conversion of convertible notes due 2023, net	58,857			58,857
Equity component of convertible notes	35,387			35,387
Cost of convertible notes hedge related to the convertible notes	(36,313)			(36,313)
Sale of warrants related to the convertible notes	29,818			29,818
Stock-based compensation	20,417			20,417
Net income (loss)	161,148					161,148
Foreign currency translation adjustments	$ (1,665)							(1,665)
Balance, ending of period (in shares) at Dec. 31, 2019	123,109		123,109
Balance, end of period at Dec. 31, 2019	$ 272,212		$ 1	458,315		(185,181)		(923)
Issuance of common stock from exercise of equity awards and employee stock purchase plan (in shares)			4,002
Issuance of common stock from exercise of equity awards and employee stock purchase plan	8,395			8,395
Payment of withholding taxes related to net share settlement of equity awards	(68,330)			(68,330)
Equity component of convertible notes due 2025, net	116,502			116,502
Conversion of convertible notes due 2023, net (in shares)			1,851
Conversion of convertible notes due 2023, net	301,015			301,015
Equity component of convertible notes	(306,220)			(306,220)
Cost of convertible notes hedge related to the convertible notes	(117,108)			(117,108)
Sale of warrants related to the convertible notes	96,351			96,351
Exercise of convertible notes due 2024 (in shares)			(1,851)
Exercise of warrants (shares)			1,851
Change in fair value of common stock related to acquisition	3,321			3,321
Stock-based compensation	42,503			42,503
Net income (loss)	133,995					133,995
Foreign currency translation adjustments	$ 1,357							1,357
Balance, ending of period (in shares) at Dec. 31, 2020	128,962		128,962
Balance, end of period at Dec. 31, 2020	$ 483,993		$ 1	$ 534,744		$ (51,186)		$ 434

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ 133,995,000	$ 161,148,000	$ (11,627,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	18,103,000	14,119,000	9,667,000
Provision for doubtful accounts	425,000	217,000	711,000
Asset impairment	0	1,124,000	1,601,000
Loss on extinguishment of debt	0	2,152,000	0
Deemed repayment of convertible notes due 2024 attributable to accreted debt discount	(3,132,000)	0	0
Non-cash interest expense	18,825,000	6,081,000	2,701,000
Fees paid for repurchase and exchange of convertible notes due 2023	0	6,000,000	0
Stock-based compensation	42,503,000	20,176,000	11,432,000
Change in fair value of derivatives	44,348,000	0	0
Deferred income taxes	(17,117,000)	(73,375,000)	123,000
Changes in operating assets and liabilities:
Accounts receivable	(34,321,000)	(68,745,000)	(13,515,000)
Inventory	(9,708,000)	(15,789,000)	9,732,000
Prepaid expenses and other assets	(14,636,000)	(14,293,000)	(3,130,000)
Intangible assets	0	0	(10,000,000)
Accounts payable, accrued and other liabilities	35,695,000	22,200,000	23,082,000
Warranty obligations	8,815,000	5,804,000	1,478,000
Deferred revenues	(10,498,000)	72,248,000	(6,123,000)
Net cash provided by operating activities	216,334,000	139,067,000	16,132,000
Cash flows from investing activities:
Purchases of property and equipment	(20,558,000)	(14,788,000)	(4,151,000)
Purchase of investment in private company	(5,010,000)	0	0
Acquisition	0	0	(15,000,000)
Net cash used in investing activities	(25,568,000)	(14,788,000)	(19,151,000)
Cash flows from financing activities:
Issuance of convertible notes, net of issuance costs	312,420,000	127,413,000	0
Purchase of convertible note hedges	(89,056,000)	(36,313,000)	0
Sale of warrants	71,552,000	29,818,000	0
Fees paid for repurchase and exchange of convertible notes due 2023	0	(6,000,000)	0
Principal payments and financing fees on debt	(2,575,000)	(45,855,000)	(9,976,000)
Proceeds from issuance of common stock, net of issuance costs	0	0	19,766,000
Proceeds from debt, net of issuance costs	0	0	68,024,000
Partial repurchase of convertible notes due 2024	(40,728,000)	0	0
Proceeds from exercise of equity awards and employee stock purchase plan	8,395,000	4,985,000	2,800,000
Payment of withholding taxes related to net share settlement of equity awards	(68,330,000)	(8,198,000)	0
Net cash provided by financing activities	191,678,000	65,850,000	80,614,000
Effect of exchange rate changes on cash and cash equivalents	826,000	(257,000)	(502,000)
Net increase in cash, cash equivalents and restricted cash	383,270,000	189,872,000	77,093,000
Cash, cash equivalents and restricted cash—Beginning of period	296,109,000	106,237,000	29,144,000
Cash. cash equivalents and restricted cash—End of period	679,379,000	296,109,000	106,237,000
Supplemental disclosures of non-cash investing and financing activities:
Total cash, cash equivalents, and restricted cash	679,379,000	106,237,000	29,144,000
Cash paid for interest	1,875,000	2,689,000	6,343,000
Cash paid for income taxes	3,452,000	1,755,000	775,000
Acquisition funded by issuance of common stock	0	0	19,219,000
Purchases of fixed assets included in accounts payable	3,630,000	672,000	895,000
Accrued interest payable unpaid upon exchange of convertible notes due 2023	0	833,000	0
Convertible Senior Notes Due 2024
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Loss on extinguishment of debt	$ 3,037,000	$ 0	$ 0

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	12 Months Ended
DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION Description of Business Enphase Energy, Inc. (the “Company”) is a global energy technology company. The Company delivers smart, easy-to-use solutions that manage solar generation, storage and communication on one single platform. The Company revolutionized the solar industry with its microinverter technology and produces a fully integrated solar-plus-storage solution. Basis of Presentation and Consolidation The accompanying consolidated financial statements are presented in accordance with accounting principles generally accepted in the United States (“U.S.”), or GAAP. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Significant estimates and assumptions reflected in the financial statements include revenue recognition, allowance for doubtful accounts, stock-based compensation, inventory valuation, accrued warranty obligations, fair value of debt derivatives and convertible notes, fair value of acquired intangible assets and goodwill, useful lives of acquired intangible assets and property and equipment, incremental borrowing rate for right-of-use assets and lease liability, probable loss recovery of tariff refunds, legal contingencies, and tax valuation allowance. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ materially from management’s estimates using different assumptions or under different conditions. The worldwide spread of the COVID-19 virus has resulted in a global slowdown of economic activity which decreased demand for a broad variety of goods and services, including from our customers, while also disrupting sales channels and marketing activities for an unknown period of time and may continue to create significant uncertainty in future operational and financial performance. The Company expects this to have negative impact on its sales and its results of operations. In preparing the Company’s consolidated financial statements in accordance with GAAP, the Company is required to make estimates, assumptions and judgments that affect the amounts reported in its financial statements and the accompanying disclosures. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgment. As of the date of issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, judgments or revise the carrying value of its assets or liabilities. These estimates may change, as new events occur and additional information is obtained, and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s financial statements.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Revenue Recognition

The Company generates revenue from sales of its solutions, which include microinverter units and related accessories, an Envoy communications gateway, the cloud-based Enlighten monitoring service, and storage solutions to distributors, large installers, original equipment manufacturers (“OEMs”) and strategic partners.

On January 1, 2018, the Company adopted Accounting Standards Codification (“ASC”) No. 606, “Revenue Recognition” (“ASC 606” or “Topic 606”) and applied the modified retrospective method to all contracts that were not completed as of January 1, 2018. The most significant impacts upon adoption of Topic 606 were how the Company accounts for revenue related to its Envoy™ communications device and related Enphase Enlighten Software™, or Enlighten, service and the timing of when certain sales incentives are recognized. The full consideration for these products represents a single performance obligation and is deferred and recognized over the estimated service period.

Revenues are recognized when control of the promised goods or services are transferred to the Company’s customers in an amount that reflects the consideration that is expected to be received in exchange for those goods or services. The Company generates all of its revenues from contracts with its customers. A description of principal activities from which the Company generates revenues follows.

•Products Delivered at a Point in Time. The Company sells its products to customers in accordance with the terms of the related customer contracts. The Company generates revenues from sales of its solutions, which include microinverter units and related accessories, an Envoy communications gateway and Enlighten service, communications accessories and storage solutions to distributors, large installers, OEMs and strategic partners. Microinverter units, microinverter accessories, and storage solutions are delivered to customers at a point in time, and the Company recognizes revenue for these products when the Company transfers control of the product to the customer, which is generally upon shipment.

•Products Delivered Over Time. The sale of an Envoy communications gateway includes the Company’s Enlighten cloud-based monitoring service. The full consideration for these products represents a single performance obligation and is deferred at the sale date and recognized over the estimated service period of 6 years. The Company also sells certain communication accessories that contain a service performance obligation to be delivered over time. The revenue from these products is recognized over the related service period, which is typically 5 or 12 years.

When the Company sells a product with more than one performance obligation, such as the IQ Combiner which includes both hardware and Envoy, the total consideration is allocated to these performance obligations based on their relative standalone selling prices. The Company previously sold its Envoy communications device to certain customers under a long-term financing arrangement. Under this financing arrangement, the Company nets the unbilled receivables against deferred revenue.

The Company records certain contra revenue promotions as variable consideration and recognizes these promotions at the time the related revenue is recorded.

The Company records upfront contract acquisition costs, such as sales commissions, to be capitalized and amortized over the estimated life of the asset. For contracts that have a duration of less than one year, the Company follows the Topic 606 practical expedient and expenses these costs when incurred. Commissions related to the Company’s sale of monitoring hardware and service are capitalized and amortized over the period of the associated revenue, which is 6 years.

See Note 3. “Revenue Recognition,” for additional information related to revenue recognition.

Cost of Revenues

The Company includes the following in cost of revenues: product costs, warranty, manufacturing personnel and logistics costs, freight costs, inventory write-downs, hosting services costs related to the Company’s Enlighten service offering, and depreciation and amortization of manufacturing test equipment. A description of principal activities from which the Company recognizes cost of revenue is as follows.

• Products Delivered at a Point in Time. Cost of revenue from these products is recognized when the Company transfers control of the product to the customer, which is generally upon shipment.

•Products Delivered Over Time. Cost of revenue from these products is recognized over the related service period.

Cash and Cash Equivalents

The Company considers all highly liquid investments, such as certificates of deposit and money market instruments with maturities of three months or less at the time of acquisition to be cash equivalents. For all periods presented, its cash balances consist of amounts held in non-interest-bearing and interest-bearing deposits and money market accounts.

Restricted Cash

Restricted cash represents cash held as certificate of deposit collateralized under a letter of credit issued to a customer. The letter of credit was required as a performance security in a face amount equal to the aggregate purchase price of the executed sales agreement. The letter of credit was issued per the terms of the executed sales agreement with a customer for safe harbor prepayment and the Company had collateralized a certificate of deposit under this letter of credit in an amount of $44.7 million, which was reflected as restricted cash on the Company’s consolidated balance sheet as of December 31, 2019. As of December 31, 2020, the Company does not have restricted cash balance.

Fair Value of Financial Instruments

The fair value of a financial instrument is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The carrying amounts of the Company’s cash, cash equivalents and restricted cash, accounts receivable, accounts payable and accrued liabilities approximate fair value because of the short maturity of those instruments. Equity investments with readily determinable fair value are carried at fair value based on quoted market prices or estimated based on market conditions and risks existing at each balance sheet date. Equity investments without readily determinable fair value are measured at cost less impairment, and are adjusted for observable price changes in orderly transactions for an identical or similar investment of the same issuer.

Convertible Note Derivatives

In March 2020, the Company issued $320 million aggregate principal amount of 0.25% convertible notes due 2025. Concurrently with the issuance of Notes due 2025, the Company entered into privately-negotiated convertible note hedge and warrant transactions which in combination are intended to reduce the potential dilution from the conversion of the Notes due 2025. The Company could not elect to issue the shares of common stock upon settlement of Notes due 2025 or convertible note hedge or warrant transactions due to insufficient authorized share capital. As a result, the embedded conversion option and warrants were accounted for as a derivative liabilities and convertible notes hedge as derivative asset and a gain (or loss) was reported in other expense, net in the consolidated statement of operations to the extent the valuation changed from the date of issuance of Notes due 2025. On May 20, 2020, at the Company’s annual meeting of stockholders, the stockholders approved an amendment to its certificate of incorporation to increase the number of authorized shares of the Company’s common stock. As a result, the Company is now be able to settle the Notes due 2025, convertible notes hedge and warrants through payment or delivery, as the case may be, of cash, shares of its common stock or a combination thereof, at the Company’s election. Accordingly, on May 20, 2020, the embedded derivative liability, convertible notes hedge and warrants liability were remeasured at a fair value and were then reclassified to additional paid-in-capital in the condensed consolidated balance sheet in the second quarter of 2020 and are no longer remeasured as long as they continue to meet the conditions for equity classification. As of December 31, 2020, the Company does not have any convertible note derivatives. See Note 11. “Debt” for additional information related to these transactions.

Accounts Receivables and Contract Assets

The Company receives payments from customers based upon contractual billing schedules. Accounts receivable are recorded when the right to consideration becomes unconditional. Contract assets include deferred product costs and commissions associated with the deferred revenue and will be amortized along with the associated revenue.

Allowance for Doubtful Accounts

The Company maintains allowances for doubtful accounts for uncollectible accounts receivable. Management estimates anticipated credit losses from doubtful accounts based on days past due, customer specific experience, collection history, the financial health of customers including from the impacts of the COVID-19 pandemic, among other factors. Accounts receivable are recorded net of allowance for doubtful accounts. The following table sets forth activities in the allowance for doubtful accounts for the periods indicated.


	December 31,
	2020		2019		2018
	(In thousands)
Balance, at beginning of year	$	564	$	2,138	$	2,378
Net charges to expenses	425		217		711
Write-offs, net of recoveries	(527)		(1,791)		(951)
Balance, at end of year	$	462	$	564	$	2,138

Inventory

Inventory is valued at the lower of cost or market. Market is current replacement cost (by purchase or by reproduction, dependent on the type of inventory). In cases where market exceeds net realizable value (i.e., estimated selling price less reasonably predictable costs of completion and disposal), inventories are stated at net realizable value. Market is not considered to be less than net realizable value reduced by an allowance for an approximately normal profit margin. The Company determines cost on a first-in first-out basis. Management assesses the valuation on a quarterly basis and writes down the value for any excess and obsolete inventory based upon expected demand, anticipated sales price, effect of new product introductions, product obsolescence, customer concentrations, product merchantability and other factors. Inventory write-downs are equal to the difference between the cost of inventories and market.

Long-Lived Assets

Property and equipment are stated at cost less accumulated depreciation. Cost includes amounts paid to acquire or construct the asset as well as any expenditure that substantially adds to the value of or significantly extends the useful life of an existing asset. Repair and maintenance costs are expensed as incurred. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets, which range from 3 to 10 years. Leasehold improvements are amortized over the shorter of the lease term or expected useful life of the improvements.

Internal-use software, whether purchased or developed, is capitalized at cost and amortized on a straight-line basis over its estimated useful life. Costs associated with internally developed software are expensed until the point at which the project has reached the development stage. Subsequent additions, modifications or upgrades to internal-use software are capitalized only to the extent that they provide additional functionality. Software maintenance and training costs are expensed in the period in which they are incurred. The capitalization of internal-use software requires judgment in determining when a project has reached the development stage and the period over which the Company expects to benefit from the use of that software.

The Company capitalizes implementation costs related to cloud computing (i.e. hosting) arrangements that are accounted for as a service contract that meets the accounting requirement for capitalization as such implementation costs were incurred to develop or utilize internal-use software hosted by a third party vendor. The capitalized implementation costs are recorded as part of “Other assets” on the consolidated balance sheet and is amortized over the length of the service contract.

Property, plant and equipment, including internal-use software, and capitalized implementation costs related to cloud computing arrangements, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset (asset group) may not be recoverable. An impairment loss would be recognized when the carrying amount of an asset exceeds the estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition. The amount of the impairment loss to be recorded is calculated by the excess of the asset’s carrying value over its fair value. Fair value is generally determined using a discounted cash flow analysis. The Company recorded asset impairment charges for specific assets that were no longer in use of approximately zero, $1.1 million and $1.6 million for the years ended 2020, 2019 and 2018, respectively. There were no events or changes in circumstances that may indicate the carrying amount of remaining assets is not recoverable.

Business Combinations

Assets acquired and liabilities assumed as part of a business acquisition are generally recorded at their fair value at the date of acquisition. The excess of purchase price over the fair value of assets acquired and liabilities assumed is recorded as goodwill. Determining fair value of identifiable assets, particularly intangibles, and liabilities acquired also requires the Company to make estimates, which are based on all available information and in some cases assumptions with respect to the timing and amount of future revenues and expenses associated with an asset. Accounting for business acquisitions requires the Company to make judgments as to whether a purchase transaction is a multiple element contract, meaning that it includes other transaction components. This judgment and determination affect the amount of consideration paid that is allocable to assets and liabilities acquired in the business purchase transaction.

Goodwill

Goodwill results from the purchase consideration paid in excess of the fair value of the net assets recorded in connection with a business acquisition. Goodwill is not amortized but is assessed for potential impairment at least annually during the fourth quarter of each fiscal year or between annual tests if an event occurs or circumstances change that would indicate the carrying amount may be impaired. Goodwill is tested at the reporting unit level, which the Company has determined to be the same as the entity as a whole (entity level). The Company first performs qualitative assessment to determine whether it is more likely than not that the fair value of our reporting unit is less than its carrying value. If, after assessing the qualitative factors, we determine that it is more likely than not that the fair value of our reporting unit is less than its carrying value, an impairment analysis will be performed.

Qualitative factors include industry and market consideration, overall financial performance, share price trends and market capitalization and Company-specific events. The Company determined, after performing a qualitative review of its reporting unit, that it is more likely than not that the fair value of our reporting unit exceeds its carrying value. Accordingly, there was no indication of impairment in the years ended 2020, 2019 and 2018 and no quantitative goodwill impairment test was performed.

Intangible Assets

Intangible assets include patents and other purchased intangible assets. Intangible assets with finite lives are amortized on a straight-line basis, with estimated useful lives ranging from 3 to 9 years. Indefinite-lived intangible assets are tested for impairment annually and are also tested for impairment between annual tests if an event occurs or circumstances change that would indicate that the carrying amount may be impaired. Intangible assets with finite lives are tested for impairment whenever events or circumstances indicate that the carrying amount of an asset (asset group) may not be recoverable. An impairment loss is recognized when the carrying amount of an asset exceeds the estimated undiscounted cash flows used in determining the fair value of the asset. The amount of the impairment loss to be recorded is calculated by the excess of the asset’s carrying value over its fair value. Fair value is generally determined using a discounted cash flow analysis. There was no impairment of intangible assets in any of the years presented.

Contract Liabilities

Contract liabilities are recorded as deferred revenue on the accompanying consolidated balance sheets and include payments received in advance of performance obligations under the contract and are realized when the associated revenue is recognized under the contract.

Warranty Obligations

Microinverters and Other Products Sold Through December 31, 2013

The Company’s warranty accrual provides for the replacement of microinverter units or other products that fail during the product’s warranty term (typically 15 years for first and second generation microinverters and up to 25 years for subsequent generation microinverters). On a quarterly basis, the Company employs a consistent, systematic and rational methodology to assess the adequacy of its warranty liability. This assessment includes updating all key estimates and assumptions for each generation of product, based on historical results, trends and the most current data available as of the filing date. The key estimates and assumptions used in the warranty liability are thoroughly reviewed by management on a quarterly basis. The key estimates used by the Company to estimate its warranty liability are: (1) the number of units expected to fail over time (i.e., failure rate); (2) the number of failed units expected to result in warranty claims over time (i.e., claim rate); and (3) the per unit cost of replacement units, including outbound shipping and limited labor costs, expected to be incurred to replace failed units over time (i.e., replacement cost).

Estimated Failure Rates — The Company’s Quality and Reliability department has primary responsibility to determine the estimated failure rates for each generation of microinverter. To establish initial failure rate estimates for each generation of microinverter, the Company’s quality engineers use a combination of industry standard Mean Time Between Failure (“MTBF”) estimates for individual components contained in its microinverters, third party data collected on similar equipment deployed in outdoor environments similar to those in which the Company’s microinverters are installed, and rigorous long term reliability and accelerated life cycle testing which simulates the service life of the microinverter in a short period of time. As units are deployed into operating environments, the Company continues to monitor product performance through its Enlighten monitoring platform. It typically takes three to nine months between the date of sale and date of end-user installation. Consequently, the Company’s ability to monitor actual failures of units sold similarly lags by three to nine months. When a microinverter fails and is returned, the Company performs diagnostic root cause failure analysis to understand and isolate the underlying mechanism(s) causing the failure. The Company then uses the results of this analysis (combined with the actual, cumulative performance data collected on those units prior to failure through Enlighten) to draw conclusions with respect to how or if the identified failure mechanism(s) will impact the remaining units deployed in the installed base.

Estimated Claim Rates — Warranty claim rate estimates are based upon observed historical trends and assumptions with respect to expected customer behavior over the warranty period. As the vast majority of the Company’s microinverters have been sold to end users for residential applications, the Company believes that warranty claim rates will be affected by changes over time in residential home ownership because the Company expects that subsequent homeowners are less likely to file claims than the homeowners who originally purchase the microinverters.

Estimated Replacement Costs — Three factors are considered in the Company’s analysis of estimated replacement cost: (1) the estimated cost of replacement microinverters; (2) the estimated cost to ship replacement microinverters to end users; and (3) the estimated labor reimbursement expected to be paid to third party installers performing replacement services for the end user. Because the Company’s warranty provides for the replacement of defective microinverters over long periods of time (between 15 and 25 years, depending on the generation of product purchased), the estimated per unit cost of current and future product generations is considered in the estimated replacement cost. Estimated costs to ship replacement units are based on observable, market-based shipping costs paid by the Company to third party freight carriers. The Company has a separate program that allows third-party installers to claim fixed-dollar reimbursements for labor costs they incur to replace failed microinverter units for a limited time from the date of original installation. Included in the Company’s estimated replacement cost is an analysis of the number of fixed-dollar labor reimbursements expected to be claimed by third party installers over the limited offering period.

In addition to the key estimates noted above, the Company also compares actual warranty results to expected results and evaluates any significant differences. Management may make additional adjustments to the warranty provision based on performance trends or other qualitative factors. If actual failure rates, claim rates, or replacement costs differ from the Company’s estimates in future periods, changes to these estimates may be required, resulting in increases or decreases in the Company’s warranty obligations. Such increases or decreases could be material.

Fair Value Option for Microinverters and Other Products Sold Since January 1, 2014

The Company’s warranty obligations related to microinverters sold since January 1, 2014 provide the Company the right, but not the requirement, to assign its warranty obligations to a third-party. Under ASC 825, “Financial Instruments” (also referred to as “fair value option”), an entity may choose to elect the fair value option for such warranties at the time it first recognizes the eligible item. The Company made an irrevocable election to account for all eligible warranty obligations associated with microinverters sold since January 1, 2014 at fair value. This election was made to reflect the underlying economics of the time value of money for an obligation that will be settled over an extended period of up to 25 years.

The Company estimates the fair value of warranty obligations by calculating the warranty obligations in the same manner as for sales prior to January 1, 2014 and applying an expected present value technique to that result. The expected present value technique, an income approach, converts future amounts into a single current discounted amount. In addition to the key estimates of failure rates, claim rates and replacement costs, the Company used certain inputs that are unobservable and significant to the overall fair value measurement. Such additional assumptions included compensation comprised of a profit element and risk premium required of a market participant to assume the obligation and a discount rate based on the Company’s credit-adjusted risk-free rate. See Note 9. “Fair Value Measurements,” for additional information.

Warranty obligations initially recorded at fair value at the time of sale will be subsequently re-measured to fair value at each reporting date. In addition, the fair value of the liability will be accreted over the corresponding term of the warranty of up to 25 years using the interest method.

Warranty for Other Products

The Company offers a 5‑year warranty for its Envoy communications gateway and a 10‑year warranty on its AC Battery storage solution. The warranties provide the Company with the right, but not the obligation, to assign its warranty obligations to a third-party. As such, warranties for Envoy and AC Battery storage solution products are accounted for under the fair value method of accounting.

Commitments and Contingencies

In the normal course of business, the Company is subject to loss contingencies and loss recoveries, such as legal proceedings and claims arising out of its business as well as tariff refunds. An accrual for a loss contingency or loss recovery is recognized when it is probable and the amount of loss or recovery can be reasonably estimated.

Research and Development Costs

The Company expenses research and development costs as incurred. Research and development expense consists primarily of product development personnel costs, including salaries and benefits, stock-based compensation, other professional costs and allocated facilities costs.

Stock-Based Compensation

Share-based payments are required to be recognized in the Company’s consolidated statements of operations based on their fair values and the estimated number of shares expected to vest. The Company measures stock-based compensation expense for all share-based payment awards, including stock options made to employees and directors, based on the estimated fair values on the date of the grant. The fair value of stock options granted is estimated using the Black-Scholes option valuation model. The fair value of restricted stock units granted is determined based on the price of the Company’s common stock on the date of grant. The fair value of non-market‑based performance stock units granted is determined based on the date of grant or when achievement of performance is probable. The fair value of market‑based performance stock units granted is determined using a Monte‑Carlo model based on the date of grant or when achievement of performance is probable.

Stock-based compensation for stock options and restricted stock units (“RSUs”) is recognized on a straight-line basis over the requisite service period. Stock-based compensation for performance stock units (“PSUs”) without market conditions is recognized when the performance condition is probable of being achieved, and then on a graded basis over the requisite service period. Stock-based compensation for PSUs with market conditions is recognized on a straight-line basis over the requisite service period. Additionally, the Company estimates its forfeiture rate annually based on historical experience and revise the estimates of forfeiture in subsequent periods if actual forfeitures differ from those estimates.

Leases

The Company determines if an arrangement is or contains a lease at inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments over the lease term.

Operating lease assets and liabilities are recognized based on the present value of the remaining lease payments discounted using the Company’s incremental borrowing rate. Operating lease assets also include initial direct costs incurred and prepaid lease payments, minus any lease incentives. The Company’s lease terms include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense is recognized on a straight-line basis over the lease term.

The Company combines the lease and non-lease components in determining the operating lease assets and liabilities.

Foreign Currency Translation

The Company and most of its subsidiaries use their respective local currency as their functional currency. Accordingly, foreign currency assets and liabilities are translated using exchange rates in effect at the end of the period. Aggregate exchange gains and losses arising from the translation of foreign assets and liabilities are included in accumulated other comprehensive income (loss) in stockholders' equity. Foreign subsidiaries that use the U.S. dollar as their functional currency remeasure monetary assets and liabilities using exchange rates in effect at the end of the period. In addition, transactions that are denominated in non-functional currency are remeasured using exchange rates in effect at the end of the period. Exchange gains and losses arising from the remeasurement of monetary assets and liabilities are included in other income (expense), net in the consolidated statements of operations. Non-monetary assets and liabilities are carried at their historical values.

Comprehensive Income (Loss)

Comprehensive income (loss) consists of two components, net income (loss) and other comprehensive income (loss). Other comprehensive income (loss) refers to gains and losses that are recorded as an element of stockholders’ equity but are excluded from net income (loss). The Company’s other comprehensive income (loss) consists of foreign currency translation adjustments for all periods presented.

Income Taxes

The Company records income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected tax consequences of temporary differences between the tax bases of assets and liabilities for financial reporting purposes and amounts recognized for income tax purposes. In estimating future tax consequences, generally all expected future events other than enactments or changes in the tax law or rates are considered. Valuation allowances are provided when necessary to reduce deferred tax assets to the amount expected to be realized.

The Company assesses the realizability of the deferred tax assets to determine release of valuation allowance as necessary. In the event the Company determines that it is more likely than not that we would be able to realize deferred tax assets in the future in excess of our net recorded amount, an adjustment to the valuation allowance for the deferred tax asset would increase income in the period such determination was made. Likewise, should it be determined that additional amounts of the net deferred tax asset will not be realized in the future, an adjustment to increase the deferred tax asset valuation allowance will be charged to income in the period such determination is made.

The Company operates in various tax jurisdictions and is subject to audit by various tax authorities. The Company follows accounting for uncertainty in income taxes which requires that the tax effects of a position be recognized only if it is “more likely than not” to be sustained based solely on its technical merits as of the reporting date. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.

Recently Adopted Accounting Pronouncements

In August 2018, the FASB issued ASU 2018-15, “Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract,” to reduce diversity in practice in accounting for the costs of implementing cloud computing arrangements that are service contracts. ASU 2018-15 allows entities to apply the guidance in the ASC 350-40, “Intangibles–Goodwill and Other–Internal-Use Software,” to determine which implementation costs are eligible to be capitalized as assets in a cloud computing arrangement that is considered a service contract. ASU 2018-15 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period. Entities have the option to apply the guidance prospectively to all implementation costs incurred after the date of adoption or retrospectively and are required to make certain disclosures in the interim and annual period of adoption. The Company adopted the new standard effective January 1, 2020 on a prospective basis and the adoption of this guidance did not have a material impact on its consolidated financial statements.

In June 2016, the FASB issued ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with a current expected credit loss (CECL) model which will result in earlier recognition of credit losses. On January 1, 2020, the Company on a prospective basis adopted Topic 326, the measurement of expected credit losses under the CECL model is applicable to financial assets measured at amortized cost, including accounts receivable. The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements.

Recently Issued Accounting Pronouncements Not Yet Effective

In August 2020, the FASB issued Account Standard Update (“ASU”) 2020-06, “Debt - Debt with Conversion and Other Options (subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (subtopic 815-40),” which reduces the number of accounting models in ASC 470-20 that require separate accounting for embedded conversion features. As a result, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost as long as no other features require bifurcation and recognition as derivatives. By removing those separation models, the effective interest rate of convertible debt instruments will be closer to the coupon interest rate. Further, the diluted net income per share calculation for convertible instruments will require the Company to use the if-converted method. The treasury stock method should no longer be used to calculate diluted net income per share for convertible instruments. The amendment will be effective for the Company with annual periods beginning January 1, 2022 and early adoption is permitted. The Company is evaluating the accounting, transition and disclosure requirements of the standard.

REVENUE RECOGNITION

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

REVENUE RECOGNITION

Disaggregated Revenue

The Company has one business activity, which is the design, manufacture and sale of solutions for the solar photovoltaic (“PV”) industry. Disaggregated revenue by primary geographical market and timing of revenue recognition for the Company’s single product line are as follows:


	Years Ended December 31,
		2020		2019
		(In thousands)
Primary geographical markets:
U.S.		$	637,879	$	523,577




International		136,546		100,756
Total		$	774,425	$	624,333

Timing of revenue recognition:
Products delivered at a point in time		$	728,254	$	584,556
Products and services delivered over time		46,171		39,777
Total		$	774,425	$	624,333

Contract Balances

Receivables, and contract assets and contract liabilities from contracts with customers are as follows:


	December 31, 2020		December 31, 2019
	(In thousands)
Receivables	$	182,165	$	145,413

Short-term contract assets (Prepaid expenses and other assets)	17,879		15,055
Long-term contract assets (Other assets)	51,986		42,087



Short-term contract liabilities (Deferred revenues)	47,665		81,783
Long-term contract liabilities (Deferred revenues)	125,473		100,204

Significant changes in the balances of contract assets (prepaid expenses and other assets) during the period are as follows (in thousands):


Contract Assets
Balance on December 31, 2019	$	57,142
Amount recognized	(17,652)
Increase	30,375
Balance as of December 31, 2020	$	69,865

Significant changes in the balances of contract liabilities (deferred revenues) during the period are as follows (in thousands):


Contract Liabilities
Balance on December 31, 2019	$	181,987
Revenue recognized	(87,555)

Increase due to billings	78,706

Balance as of December 31, 2020	$	173,138

Remaining Performance Obligations

Estimated revenue expected to be recognized in future periods related to performance obligations that are unsatisfied or partially unsatisfied at the end of the reporting period are as follows:


	December 31, 2020
	(In thousands)
Fiscal year:
2021	$	47,665
2022	38,402
2023	32,569
2024	27,311
2025	20,291
Thereafter	6,900
Total	$	173,138

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130554-203045

+ Details

INVENTORY

12 Months Ended

Dec. 31, 2020

Inventory Disclosure [Abstract]

INVENTORY

Inventory consist of the following:



	December 31, 2020		December 31, 2019
	(In thousands)
Raw materials	$	10,140	$	4,197
Finished goods	31,624		27,859
Total inventory	$	41,764	$	32,056

PROPERTY AND EQUIPMENT, NET

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT, NET

Property and equipment consist of the following:


	Estimated Useful Life	December 31,
		2020		2019
	(Years)	(In thousands)
Equipment and machinery	3-10	$	63,411	$	48,114
Furniture and fixtures	5-10	2,532		2,404
Computer equipment	3-5	2,972		1,698
Capitalized software costs	3-5	17,004		11,656
Leasehold improvements	3-10	9,021		8,713
Construction in process		9,747		8,446
Total		104,687		81,031
Less accumulated depreciation and amortization		(61,702)		(52,095)
Property and equipment, net		$	42,985	$	28,936

Depreciation expense for property and equipment for the years ended December 31, 2020, 2019 and 2018 was $9.7 million, $7.3 million and $8.3 million, respectively.

As of December 31, 2020 and 2019, unamortized capitalized software costs were $4.8 million and $0.8 million, respectively.

GOODWILL AND INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL AND INTANGIBLE ASSETS

The Company’s goodwill and purchased intangible assets as of December 31, 2020 and December 31, 2019 are as follows:


	December 31, 2020								December 31, 2019
	Gross		Additions		Accumulated Amortization		Net		Gross		Accumulated Amortization		Net
	(In thousands)
Goodwill	$	24,783	$	—	$	—	$	24,783	$	24,783	$	—	$	24,783

Intangible assets:
Other indefinite-lived intangibles	286		—		—		286		286		—		286

Intangible assets with finite lives:

Developed technology	13,100		—		(5,276)		7,824		13,100		(3,093)		10,007
Customer relationships	23,100		3,321		(5,723)		20,698		23,100		(2,814)		20,286
Total purchased intangible assets	$	36,486	$	3,321	$	(10,999)	$	28,808	$	36,486	$	(5,907)	$	30,579

Amortization expense related to finite-lived intangible assets are as follows:


	Years Ended December 31,
		2020		2019
		(In thousands)
Developed technology, and patents and licensed technology		$	2,183	$	2,184
Customer relationships		2,909		2,543
Total amortization expense		$	5,092	$	4,727

Amortization of developed technology, patents and licensed technology is recorded to sales and marketing expense. The developed technology acquired from the Company’s acquisition of SunPower Corporation’s (“SunPower”) microinverter business in August 2018 was embedded in the microinverters that SunPower sold to its customers. The Company does not actively use the developed technology acquired from SunPower and holds the developed technology to prevent others from using it. Accordingly, the Company accounts for the developed technology as a defensive intangible asset and amortizes the associated value over a period of six years from the date of acquisition.

The master supply agreement (“MSA”) entered into with SunPower in August 2018 provides the Company with the exclusive right to supply SunPower with module level power electronics for a period of five years, with options for renewals. The exclusivity arrangement extends throughout the term of the MSA, which comprises all of the expected cash flows from the customer relationship intangible asset, and was a condition to, and was an essential part of the acquisition of SunPower’s microinverter business by the Company. As the original $23.1 million fair value ascribed to the customer relationship intangible asset represents payments to a customer, the Company amortizes the value of the customer relationship intangible asset as a reduction to revenue using a pattern of economic benefit method over a useful life of nine years. During the fourth quarter of 2020, the Company signed an amendment to the MSA which increased the period of exclusive right to supply by another three months, and the associated incremental non-cash $3.3 million fair value of equity is added to the customer relationship intangible asset will follow the same amortization pattern.

ACCRUED LIABILITIES

12 Months Ended

Dec. 31, 2020

Payables and Accruals [Abstract]

ACCRUED LIABILITIES

Accrued liabilities consist of the following:


	December 31, 2020		December 31, 2019
	(In thousands)
Salaries, commissions, incentive compensation and benefits	$	6,634	$	5,524
Customer rebates and sales incentives	36,622		24,198
Freight	10,300		4,908
Operating lease liabilities, current	4,542		3,170
Liability due to supply agreements	5,500		1,729
Other	12,944		7,563
Total accrued liabilities	$	76,542	$	47,092

WARRANTY OBLIGATIONS

12 Months Ended

Dec. 31, 2020

Product Warranties Disclosures [Abstract]

WARRANTY OBLIGATIONS

The Company’s warranty activities were as follows:


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Warranty obligations, beginning of period		$	37,098	$	31,294	$	29,816
Accruals for warranties issued during period		7,021		5,244		3,040
Changes in estimates		9,954		8,591		6,515
Settlements		(12,811)		(10,881)		(8,579)
Increase due to accretion expense		3,255		2,326		1,989
Other		1,396		524		(1,487)
Warranty obligations, end of period		45,913		37,098		31,294
Less: current portion		(11,260)		(10,078)		(8,083)
Noncurrent		$	34,653	$	27,020	$	23,211

Changes in Estimates

On a quarterly basis, the Company uses the best and most complete underlying information available, following a consistent, systematic and rational methodology to determine its warranty obligations. The Company considers all available evidence to assess the reasonableness of all key assumptions underlying its estimated warranty obligations for each generation of microinverter. The changes in estimates discussed below resulted from consideration of new or additional information becoming available and subsequent developments. Changes in estimates included in the table above were comprised of the following:

2020

In 2020, the Company recorded a $8.8 million increase to warranty expense based on continuing analysis of field performance data and diagnostic root-cause failure analysis primarily relating to its prior generation products. The Company also recorded additional warranty expense of $1.2 million related to unit costs for prior generation microinverter replacement driven by tariffs and labor reimbursement costs expected to be paid to third party installers performing replacement services.

2019

In 2019, the Company recorded a $5.5 million increase to warranty expense related to cost increases primarily driven by increased U.S. tariffs announced during 2019 for its products manufactured in China. The Company also recorded additional warranty expense of $3.1 million based on continuing analysis of field performance data and diagnostic root-cause failure analysis primarily relating to its second and third generation products, partially offset by improved failure rates for its IQ7 series.

2018

In 2018, the Company recorded a $0.9 million increase to warranty expense related to cost increases primarily for backwards compatibility cables, supply constrained inventory components as well as tariffs. The Company also recorded additional warranty expense of $3.3 million based on continuing analysis of field performance data and diagnostic root-cause failure analysis primarily relating to its second and third generation products. In addition, the Company recorded an increase of $2.1 million related to increased estimated claim rates and an increase to warranty expense of $0.2 million for labor reimbursement costs expected to be paid to third party installers performing replacement services. These increases were partially offset by a $1.5 million reduction to warranty expense, presented as “Other” in the table above, related to changes in the discount rates for fair value accounting.

FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

FAIR VALUE MEASUREMENTS

The accounting guidance defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities recorded at fair value, the Company considers the principal or most advantageous market in which it would transact and considers assumptions that market participants would use when pricing the asset or liability, such as inherent risk, transfer restrictions, and risk of nonperformance.

The fair value hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. An asset’s or liability’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Three levels of inputs may be used to measure fair value:

•Level 1 - Valuations based on quoted prices in active markets for identical assets or liabilities that the Company is able to access. Since valuations are based on quoted prices that are readily and regularly available in an active market, valuation of such assets or liabilities do not entail a significant degree of judgment.

•Level 2 - Valuations based on one or more quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly.

•Level 3 - Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

Level 1. The Company considers all highly liquid investments, such as certificates of deposit and money market instruments with maturities of three months or less at the time of acquisition to be cash equivalents. For all periods presented, its cash balances consist of amounts held in non-interest-bearing and interest-bearing deposits and money market accounts and are within Level 1 of the fair value hierarchy because they are valued using quoted market prices for identical instruments in active markets. As of December 31, 2020, cash and cash equivalents balance includes money market funds of $654.7 million.

Level 2.

Convertible Notes due 2025 Derivatives.

On March 9, 2020, the Company issued $320 million aggregate principal amount of 0.25% convertible senior notes due 2025 (the “Notes due 2025”). Concurrently with the issuance of Notes due 2025, the Company entered into privately-negotiated convertible note hedge and warrant transactions which in combination are intended to reduce the potential dilution from the conversion of the Notes due 2025. On May 20, 2020, at the Company’s annual meeting of stockholders, the stockholders approved an amendment to its certificate of incorporation to increase the number of authorized shares of the Company’s common stock. As a result, the Company satisfied the share reservation condition (as defined in the relevant indenture associated with the Notes due 2025). The Company will now be able to settle the Notes due 2025, convertible notes hedge and warrants through payment or delivery, as the case may be, of cash, shares of its common stock or a combination thereof, at the Company’s election. Accordingly, on May 20, 2020, the embedded derivative liability, convertible notes hedge and warrants liability were remeasured at a fair value of $116.3 million, $117.1 million and $96.4 million, respectively, and were then reclassified to additional paid-in-capital in the condensed consolidated balance sheet in the second quarter of 2020 and are no longer remeasured as long as they continue to meet the conditions for equity classification. See Note 11. “Debt” for additional information related to these transactions.

The fair value of the Convertible notes embedded derivative was estimated using Binomial Lattice model and the fair value of Convertible notes hedge and Warrants liability was estimated using Black-Scholes-Merton model. The significant observable inputs, either directly or indirectly, and assumptions used in the models to calculate the fair value of the derivatives include the Company’s common stock price, exercise price of the derivatives, risk-free interest rate, volatility, annual coupon rate and remaining contractual term.

Notes due 2025 and Notes due 2024.

The Company carries the Notes due 2025 and Notes due 2024 (as defined below) at face value less unamortized discount and issuance costs on its consolidated balance sheets. The fair value of the Notes due 2025 and Notes due 2024 was $725.5 million and $747.1 million, respectively, as of December 31, 2020 based on the closing trading prices per $100 principal amount as of the last day of trading for the period. The Company considers the fair value of the Notes due 2025 and Notes due 2024 to be a Level 2 measurement as they are not actively traded.

Level 3.

Equity investments without readily determinable fair value.

In December 2020, the Company invested approximately $5.0 million in a privately-held company without readily determinable market value, which is included in “Other assets” in the consolidated balance sheet. The Company has elected the measurement alternative for equity investments that do not have readily determinable fair values. The Company did not record an impairment charge on its investment during the year ended December 31, 2020, as no events or changes in circumstances were identified which could result as an indicator for impairment. Further, there were no observable price changes in orderly transactions for the identical or a similar investment of the same issuer during the year ended December 31, 2020. Equity investments without readily determinable fair value are classified within Level 3 in the fair value hierarchy because the Company estimates the value based on valuation methods using a combination of observable and unobservable inputs including valuation ascribed to the issuing company in subsequent financing rounds, volatility in the results of operations of the issuers and rights and obligations of the securities the Company holds.

Warranty Obligations.

The following table presents the Company’s warranty obligations that were measured at fair value on a recurring basis and its categorization within the fair value hierarchy.


	December 31, 2020		December 31, 2019
	(In thousands)
	Level 3		Level 3







Liabilities:







Warranty obligations
Current	$	8,267	$	6,794
Non-current	20,469		13,012
Total warranty obligations measured at fair value	28,736		19,806
Total liabilities measured at fair value	$	28,736	$	19,806

Fair Value Option for Warranty Obligations Related to Microinverters and Other Products Sold Since January 1, 2014

The Company estimates the fair value of warranty obligations by calculating the warranty obligations in the same manner as for sales prior to January 1, 2014 and applying an expected present value technique to that result. The expected present value technique, an income approach, converts future amounts into a single current discounted amount. In addition to the key estimates of failure rates, claim rates and replacement costs, the Company used certain Level 3 inputs which are unobservable and significant to the overall fair value measurement. Such additional assumptions included a discount rate based on the Company’s credit-adjusted risk-free rate and compensation comprised of a profit element and risk premium required of a market participant to assume the obligation.

The following table provides information regarding changes in nonfinancial liabilities related to the Company’s warranty obligations measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the periods indicated.


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Balance at beginning of period		$	19,806	$	11,757	$	9,791
Accruals for warranties issued during period		7,021		5,244		3,040
Changes in estimates		5,039		6,167		2,455
Settlements		(7,781)		(6,212)		(4,030)
Increase due to accretion expense		3,255		2,326		1,989
Other		1,396		524		(1,488)
Balance at end of period		$	28,736	$	19,806	$	11,757

Quantitative and Qualitative Information about Level 3 Fair Value Measurements

As of December 31, 2020 and December 31, 2019, the significant unobservable inputs used in the fair value measurement of the Company’s liabilities designated as Level 3 are as follows:

Percent Used

(Weighted Average)

Item Measured at Fair Value

Valuation Technique

Description of Significant Unobservable Input

December 31,
2020

December 31,
2019

Warranty obligations for microinverters sold since January 1, 2014

Discounted cash flows

Profit element and risk premium

15%

14%

Credit-adjusted risk-free rate

13%

16%

Sensitivity of Level 3 Inputs - Warranty Obligations

Each of the significant unobservable inputs is independent of the other. The profit element and risk premium are estimated based on requirements of a third-party participant willing to assume the Company’s warranty obligations. The credit‑adjusted risk‑free rate (“discount rate”) is determined by reference to the Company’s own credit standing at the fair value measurement date. Increasing the profit element and risk premium input by 100 basis points would result in a $0.2 million increase to the liability. Decreasing the profit element and risk premium by 100 basis points would result in a $0.2 million reduction of the liability. Increasing the discount rate by 100 basis points would result in a $1.4 million reduction of the liability. Decreasing the discount rate by 100 basis points would result in a $1.6 million increase to the liability.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

RESTRUCTURING

12 Months Ended

Dec. 31, 2020

Restructuring and Related Activities [Abstract]

RESTRUCTURING

Restructuring expense consist of the following:


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Redundancy and employee severance and benefit arrangements		$	—	$	1,575	$	2,228
Asset impairments		—		1,124		1,601
Consultants engaged in restructuring activities		—		—		—
Lease loss reserves (benefit)		—		(100)		300

Total restructuring charges		$	—	$	2,599	$	4,129

2018 Plan

In the third quarter of 2018, the Company began implementing restructuring actions (the “2018 Plan”) to lower its operating expenses. The restructuring actions include reorganization of the Company’s global workforce, elimination of certain non-core projects and consolidation of facilities. The Company completed its restructuring activities under the 2018 Plan in 2019.

The following table provides information regarding changes in the Company’s 2018 Plan accrued restructuring balance for the periods indicated.


	Redundancy and Employee Severance and Benefits		Lease Loss Reserves and Contractual Obligations		Total
	(In thousands)




Balance as of December 31, 2018	$	904	$	288	$	1,192
Charges	2,699		—		2,699
Cash payments	(1,610)		—		(1,610)
Non-cash settlement and other	(1,993)		(288)		(2,281)
Balance as of December 31, 2019	$	—	$	—	$	—

The following table presents the details of the Company’s restructuring charges under the 2018 Plan for the period indicated:


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Redundancy and employee severance and benefit arrangements		$	—	$	1,575	$	2,228
Asset impairments		—		1,124		1,636

Lease loss reserves (benefit)		—		(100)		340

Total restructuring charges		$	—	$	2,599	$	4,204

2016 Plan

In the third quarter of 2016, the Company began implementing restructuring actions (the “2016 Plan”) to lower its operating expenses. The restructuring actions have included reductions in the Company’s global workforce, the elimination of certain non-core projects, consolidation of office space at the Company’s corporate headquarters and the engagement of management consultants to assist the Company in making organizational and structural changes to improve operational efficiencies and reduce expenses. The Company completed its restructuring activities under the 2016 Plan in 2017.

The following table provides information regarding changes in the Company’s 2016 Plan accrued restructuring balance for the periods indicated.


	Employee Severance and Benefits		Asset Impairments		Lease Loss Reserves and Contractual Obligations		Total
	(In thousands)








Balance as of December 31, 2018	—		—		$	1,591	1,591


Other (1)	—		—		(1,591)		(1,591)
Balance as of December 31, 2019	$	—	$	—	$	—	$	—

(1) Adoption of ASU 2016-02

DEBT

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

DEBT

The following table provides information regarding the Company’s long-term debt.


	December 31, 2020		December 31, 2019
	(In thousands)
Convertible notes
Notes due 2025	$	320,000	$	—
Less: unamortized discount and issuance costs	(64,979)		—
Carrying amount of Notes due 2025	255,021		—



Notes due 2024	88,140		132,000
Less: unamortized discount and issuance costs	(19,119)		(35,815)
Carrying amount of Notes due 2024	69,021		96,185

Notes due 2023	5,000		5,000
Less: unamortized issuance costs	(102)		(143)
Carrying amount of Notes due 2023	4,898		4,857









Sale of long-term financing receivable recorded as debt	1,925		4,501


Total carrying amount of debt	330,865		105,543

Less: current portion of convertible notes and long-term financing receivable recorded as debt	(325,967)		(2,884)
Long-term debt	$	4,898	$	102,659

Convertible Senior Notes due 2025

On March 9, 2020, the Company issued $320.0 million aggregate principal amount of the Notes due 2025. The Notes due 2025 are general unsecured obligations and bear interest at an annual rate of 0.25% per year, payable semi-annually on March 1 and September 1 of each year, beginning September 1, 2020. The Notes due 2025 are governed by an indenture between the Company and U.S. Bank National Association, as trustee. The Notes due 2025 will mature on March 1, 2025, unless earlier repurchased by the Company or converted at the option of the holders. The Company may not redeem the notes prior to the maturity date, and no sinking fund is provided for the notes. The Notes due 2025 may be converted, under certain circumstances as described below, based on an initial conversion rate of 12.2637 shares of common stock per $1,000 principal amount (which represents an initial conversion price of $81.54 per share). The conversion rate for the Notes due 2025 will be subject to adjustment upon the occurrence of certain specified events but will not be adjusted for accrued and unpaid interest. In addition, upon the occurrence of a make-whole fundamental change (as defined in the relevant indenture), the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its notes in connection with such make-whole fundamental change. The Company received approximately $313.0 million in net proceeds, after deducting the initial purchasers’ discount, from the issuance of the Notes due 2025.

The Notes due 2025 may be converted prior to the close of business on the business day immediately preceding September 1, 2024, in multiples of $1,000 principal amount, at the option of the holder only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on June 30, 2020 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the five business day period after any five consecutive trading day period (the “measurement period”) in which the “trading price” (as defined in the relevant indenture) per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; or (3) upon the occurrence of specified corporate events. On and after September 1, 2024 until the close of business on the second scheduled trading day immediately preceding the maturity date of March 1, 2025, holders may convert their notes at any time, regardless of the foregoing circumstances. Upon the occurrence of a fundamental change (as defined in the relevant indenture), holders may require the Company to repurchase all or a portion of their Notes due 2025 for cash at a price equal to 100% of the principal amount of the notes to be repurchased plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

As of December 31, 2020, the sale price of the Company’s common stock was greater than or equal to $106.00 (130% of the notes conversion price) for at least 20 trading days (whether consecutive or not) during a period of 30 consecutive trading days preceding the quarter-ended December 31, 2020. As a result, as of December 31, 2020, the Notes due 2025 are convertible at the holders’ option through March 31, 2021. Accordingly, the Company classified the net carrying amount of the Notes due 2025 of $255.0 million as Debt, current on the consolidated balance sheet as of December 31, 2020.

For the period from March 9, 2020, the issuance date, through May 19, 2020, the number of authorized and unissued shares of the Company’s common stock that are not reserved for other purposes was less than the maximum number of underlying shares that would be required to settle the Notes due 2025 into equity. Accordingly, unless and until the Company had a number of authorized shares that were not issued or reserved for any other purpose that equaled or exceeded the maximum number of underlying shares (“share reservation condition”), the Company would be required to pay to the converting holder in respect of each $1,000 principal amount of notes being converted solely in cash in an amount equal to the sum of the daily conversion values for each of the 20 consecutive trading days during the related observation period. However, following satisfaction of the share reservation condition, the Company could settle conversions of notes through payment or delivery, as the case may be, of cash, shares of the Company’s common stock or a combination of cash and shares of its common stock, at the Company’s election.

In accounting for the issuance of the Notes due 2025, on March 9, 2020, the conversion option of the Notes due 2025 was deemed an embedded derivative requiring bifurcation from the Notes due 2025 (“host contract”) and separate accounting as an embedded derivative liability, as a result of the Company not having the necessary number of authorized but unissued shares of its common stock available to settle the conversion option of the Notes due 2025 in shares. The proceeds from the Notes due 2025 were first allocated to the embedded derivative liability and the remaining proceeds were then allocated to the host contract. On March 9, 2020, the carrying amount of the embedded derivative liability of $68.7 million representing the conversion option was determined using the Binomial Lattice model and the remaining $251.3 million was allocated to the host contract. The difference between the principal amount of the Notes due 2025 and the fair value of the host contract (the “debt discount”) is amortized to interest expense using the effective interest method over the term of the Notes due 2025.

On May 20, 2020, at the Company’s annual meeting of stockholders, the stockholders approved an amendment to the Amended and Restated Certificate of Incorporation to increase the number of authorized shares of the Company’s common stock, par value $0.00001 per share, from 150,000,000 shares to 200,000,000 shares (the “Amendment”). The Amendment became effective upon filing with the Secretary of State of Delaware on May 20, 2020. As a result, the Company satisfied the share reservation condition. The Company may now settle the Notes due 2025 and warrants issued in conjunction with the Notes due 2025 through payment or delivery, as the case may be, of cash, shares of its common stock or a combination of cash and shares of its common stock, at the Company’s election. Accordingly, on May 20, 2020, the embedded derivative liability was remeasured at a fair value of $116.3 million and was then reclassified to additional paid-in-capital in the condensed consolidated balance sheet in the second quarter of 2020 and is no longer remeasured as long as it continues to meet the conditions for equity classification. The Company recorded the change in the fair value of the embedded derivative in other expense, net in the consolidated statement of operations during the year ended December 31, 2020.

The Company separated the Notes due 2025 into liability and equity components, this resulted in a tax basis difference associated with the liability component that represents a temporary difference. The Company recognized the deferred taxes of $0.2 million for the tax effect of that temporary difference as an adjustment to the equity component included in additional paid-in capital in the consolidated balance sheet.

The following table presents the fair value and the change in fair value for the convertible note embedded derivative (in thousands):


Convertible note embedded derivative liability

Fair value as of March 9, 2020	$	68,700



Change in the fair value	47,600
Fair value as of May 20, 2020	$	116,300

Debt issuance costs for the issuance of the Notes due 2025 were approximately $7.6 million, consisting of initial purchasers' discount and other issuance costs. In accounting for the transaction costs, the Company allocated the total amount incurred to the Notes due 2025 host contract. Transaction costs were recorded as debt issuance cost (presented as contra debt in the consolidated balance sheet) and are being amortized to interest expense over the term of the Notes due 2025.

The following table presents the total amount of interest cost recognized relating to the Notes due 2025 (in thousands):


	Year Ended December 31, 2020



Contractual interest expense	$	649
Amortization of debt discount	10,072
Amortization of debt issuance costs	1,229
Total interest cost recognized	$	11,950

The derived effective interest rate on the Notes due 2025 host contract was determined to be 5.18%, which remain unchanged from the date of issuance. The remaining unamortized debt discount was $58.6 million as of December 31, 2020, and will be amortized over approximately 4.2 years.

Notes due 2025 Hedge and Warrant Transactions

In connection with the offering of the Notes due 2025, the Company entered into privately-negotiated convertible note hedge transactions pursuant to which the Company has the option to purchase a total of approximately 3.9 million shares of its common stock (subject to anti-dilution adjustments), which is the same number of shares initially issuable upon conversion of the notes, at a price of $81.54 per share, which is the initial conversion price of the Notes due 2025. The total cost of the convertible note hedge transactions was approximately $89.1 million. The convertible note hedge transactions are expected generally to reduce potential dilution to the Company’s common stock upon any conversion of the Notes due 2025 and/or offset any cash payments the Company is required to make in excess of the principal amount of converted notes, as the case may be. As of December 31, 2020, the Company had not purchased any shares under the convertible note hedge transactions.

Additionally, the Company separately entered into privately-negotiated warrant transactions (the “Warrants”) whereby the Company sold warrants to acquire approximately 3.9 million shares of the Company’s common stock (subject to anti-dilution adjustments) at an initial strike price of $106.94 per share. The Company received aggregate proceeds of approximately $71.6 million from the sale of the Warrants. If the market value per share of the Company’s common stock, as measured under the Warrants, exceeds the strike price of the Warrants, the Warrants will have a dilutive effect on the Company’s earnings per share, unless the Company elects, subject to certain conditions, to settle the Warrants in cash. Taken together, the purchase of the convertible note hedges and the sale of the Warrants are intended to reduce potential dilution from the conversion of the Notes due 2025 and to effectively increase the overall conversion price from $81.54 to $106.94 per share. The Warrants are only exercisable on the applicable expiration dates in accordance with the agreements relating to each of the Warrants. Subject to the other terms of the Warrants, the first expiration date applicable to the Warrants is June 1, 2025, and the final expiration date applicable to the Warrants is September 23, 2025. As of December 31, 2020, the Warrants had not been exercised and remained outstanding.

For the period from March 9, 2020, the issuance date of the convertible notes hedge and warrant transactions, through May 19, 2020, the number of authorized and unissued shares of the Company’s common stock that are not reserved for other purposes was less than the maximum number of underlying shares that will be required to settle the Notes due 2025 through the delivery of shares of the Company’s common stock. Accordingly, the convertibles note hedge and the warrant transactions could only be settled on net cash settlement basis. As a result the convertible note hedge and the warrants transaction were classified as a Convertible notes hedge asset and Warrants liability, respectively, in the consolidated balance sheet and the change in fair value of derivatives was included in other expense, net in the consolidated statement of operations.

On May 20, 2020, at the Company’s annual meeting of stockholders, the stockholders approved the Amendment, and as a result, the Convertible notes hedge asset and Warrants liabilities were remeasured at a fair value of $117.1 million and $96.4 million, respectively, and were then reclassified to additional paid-in-capital in the condensed consolidated balance sheet in the second quarter of 2020 and is no longer remeasured as long as they continue to meet the conditions for equity classification. The change in the fair value of the Convertible notes hedge asset and Warrants liability were recorded in other expense, net in the consolidated statements of operations during the year ended December 31, 2020.

The following table presents the fair value and the change in fair value for the Convertible notes hedge asset and Warrants liability:


	Convertible notes hedge		Warrants liability
	(In thousands)
Fair value as of March 9, 2020	$	89,056	$	71,552



Change in the fair value	28,052		24,799
Fair value as of May 20, 2020	$	117,108	$	96,351

Convertible Senior Notes due 2024

On June 5, 2019, the Company issued $132.0 million aggregate principal amount of 1.0% convertible senior notes due 2024 (the “Notes due 2024”). The Notes due 2024 are general unsecured obligations and bear interest at an annual rate of 1.0% per year, payable semi-annually on June 1 and December 1 of each year, beginning December 1, 2019. The Notes due 2024 are governed by an indenture between the Company and U.S. Bank National Association, as trustee. The Notes due 2024 will mature on June 1, 2024, unless earlier repurchased by the Company or converted at the option of the holders. The Company may not redeem the notes prior to the maturity date, and no sinking fund is provided for the notes. The Notes due 2024 may be converted, under certain circumstances as described below, based on an initial conversion rate of 48.7781 shares of common stock per $1,000 principal amount (which represents an initial conversion price of $20.5010 per share). The conversion rate for the Notes due 2024 will be subject to adjustment upon the occurrence of certain specified events but will not be adjusted for accrued and unpaid interest. In addition, upon the occurrence of a make-whole fundamental change (as defined in the relevant indenture), the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its notes in connection with such make-whole fundamental change. The Company received approximately $128.0 million in net proceeds, after deducting the initial purchasers’ discount, from the issuance of the Notes due 2024.

The Notes due 2024 may be converted on any day prior to the close of business on the business day immediately preceding December 1, 2023, in multiples of $1,000 principal amount, at the option of the holder only under any of the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on September 30, 2019 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to $26.6513 (130% of the conversion price) on each applicable trading day; (2) during the five business day period after any five consecutive trading day period (the “measurement period”) in which the “trading price” (as defined in the relevant indenture) per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; or (3) upon the occurrence of specified corporate events. On and after December 1, 2023 until the close of business on the second scheduled trading day immediately preceding the maturity date of June 1, 2024, holders may convert their notes at any time, regardless of the foregoing circumstances. Upon the occurrence of a fundamental change (as defined in the relevant indenture), holders may require the Company to repurchase all or a portion of their Notes due 2024 for cash at a price equal to 100% of the principal amount of the notes to be repurchased plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

As of December 31, 2020, the sale price of the Company’s common stock was greater than or equal to $26.6513 (130% of the notes conversion price) for at least 20 trading days (whether consecutive or not) during a period of 30 consecutive trading days preceding the quarter-ended December 31, 2020. As a result, as of December 31, 2020, the Notes due 2024 are convertible at the holders’ option through March 31, 2021. Accordingly, the Company classified the net carrying amount of the Notes due 2024 of $69.0 million as Debt, current on the consolidated balance sheet as of December 31, 2020. From January 1, 2021 through February 12, 2021, the Company has received the request for conversion of approximately $61.5 million in principal amount of Notes due 2024, of which the Company has elected to settle the aggregate principal amount of the Notes due 2024 in a combination of cash and any excess in shares of the Company’s common stock in accordance with the applicable indenture. Such conversion will be settled in March 2021.

In accounting for the issuance of the Notes due 2024, on June 5, 2019, the Company separated the Notes due 2024 into liability and equity components. The carrying amount of the liability component of approximately $95.6 million was calculated by using a discount rate of 7.75%, which was the Company’s borrowing rate on the date of the issuance of the notes for a similar debt instrument without the conversion feature. The carrying amount of the equity component of approximately $36.4 million, representing the conversion option, was determined by deducting the fair value of the liability component from the par value of the Notes due 2024. The equity component of the Notes due 2024 is included in additional paid-in capital in the consolidated balance sheet and is not remeasured as long as it continues to meet the conditions for equity classification. The difference between the principal amount of the Notes due 2024 and the liability component (the “debt discount”) is amortized to interest expense using the effective interest method over the term of the Notes due 2024.

The Company separated the Notes due 2024 into liability and equity components, this resulted in a tax basis difference associated with the liability component that represents a temporary difference. The Company recognized the deferred taxes of $0.3 million for the tax effect of that temporary difference as an adjustment to the equity component included in additional paid-in capital in the consolidated balance sheet.

Debt issuance costs for the issuance of the Notes due 2024 were approximately $4.6 million, consisting of initial purchasers' discount and other issuance costs. In accounting for the transaction costs, the Company allocated the total amount incurred to the liability and equity components using the same proportions as the proceeds from the Notes due 2024. Transaction costs attributable to the liability component were approximately $3.3 million, were recorded as debt issuance cost (presented as contra debt in the consolidated balance sheet) and are being amortized to interest expense over the term of the Notes due 2024. The transaction costs attributable to the equity component were approximately $1.3 million and were netted with the equity component in stockholders’ equity. As of December 31, 2020 and 2019, the unamortized deferred issuance cost for the Notes due 2024 was $1.5 million and $2.9 million, respectively, on the consolidated balance sheets.

During the fourth quarter of 2020, holders converted $43.9 million in aggregate principal amount of the Notes due 2024, the principal amount of which was repaid in cash. Of the $43.9 million in aggregate principal amount, $38.5 million in aggregate principal amount was settled pursuant to an exchange agreement entered into in December 2020 with certain holders of Notes due 2024. The Company also issued 1.9 million shares of its common stock to the holders with an aggregate fair value of $301.0 million, representing the conversion value in excess of the principal amount of the Notes due 2024, which were fully offset by shares received from the Company’s exercise of the associated note hedging arrangements discussed below. The total amount of $43.9 million paid to partially settle the Notes due 2024 was allocated between the liability and equity components of the amount extinguished by determining the fair value of the liability component immediately prior to the notes settlement and allocating that portion of the conversion price to the liability component in the amount of $37.2 million. The residual of the conversion price of $6.7 million was allocated to the equity component of the Notes due 2024 as a reduction of additional paid-in capital. The fair value of the notes settlement was calculated using a discount rate of 5.75%, representing an estimate of the Company's borrowing rate at the date of repurchase with a remaining expected life of approximately 3.6 years. As part of the settlement, the Company wrote-off the $8.9 million unamortized debt discount and $0.8 million debt issuance cost apportioned to the principal amount of Notes due 2024 settled. The Company also recorded a loss on partial settlement of the Notes due 2024 of $3.0 million in Other expense, net, representing the difference between the consideration attributed to the liability component and the sum of the net carrying amount of the liability component and unamortized debt issuance costs. As of December 31, 2020, $88.1 million aggregate principal amount of the Notes due 2024 remains outstanding.

The following table presents the total amount of interest cost recognized in the statement of operations relating to the Notes due 2024:


	Years Ended December 31,
		2020		2019
		(In thousands)
Contractual interest expense		$	1,284	$	759
Amortization of debt discount		6,325		3,492
Amortization of debt issuance costs		646		375
Total interest cost recognized		$	8,255	$	4,626

The effective interest rate on the liability component Notes due 2024 was 7.75% for the year ended December 31, 2020, which remains unchanged from the date of issuance. The remaining unamortized debt discount was $17.6 million and $32.9 million as of December 31, 2020 and December 31, 2019, respectively, and will be amortized over approximately 3.4 years from December 31, 2020.

Notes due 2024 Hedge and Warrant Transactions

In connection with the offering of the Notes due 2024, the Company entered into privately-negotiated convertible note hedge transactions pursuant to which the Company has the option to purchase a total of approximately 6.4 million shares of its common stock (subject to anti-dilution adjustments), which is the same number of shares initially issuable upon conversion of the notes, at a price of $20.5010 per share, which is the initial conversion price of the Notes due 2024. The total cost of the convertible note hedge transactions was approximately $36.3 million. The convertible note hedge transactions are expected generally to reduce potential dilution to the Company’s common stock upon any conversion of the Notes due 2024 and/or offset any cash payments the Company is required to make in excess of the principal amount of converted notes, as the case may be.

As a result of the conversion request received from the holders of $43.9 million in aggregate principal amount of the Notes due 2024 in the fourth quarter of 2020, the Company exercised the 2.1 million shares representing proportionate number of the convertible note hedge transaction and received 1.9 million shares on net basis of its common stock during the period. As of December 31, 2020, option to purchase a total of approximately 4.3 million shares remain outstanding.

Additionally, the Company separately entered into privately-negotiated warrant transactions (the “Warrants”) whereby the Company sold warrants to acquire approximately 6.4 million shares of the Company’s common stock (subject to anti-dilution adjustments) at an initial strike price of $25.2320 per share. The Company received aggregate proceeds of approximately $29.8 million from the sale of the Warrants. If the market value per share of the Company’s common stock, as measured under the Warrants, exceeds the strike price of the Warrants, the Warrants will have a dilutive effect on the Company’s earnings per share, unless the Company elects, subject to certain conditions, to settle the Warrants in cash. Taken together, the purchase of the convertible note hedges and the sale of the Warrants are intended to reduce potential dilution from the conversion of the Notes due 2024 and to effectively increase the overall conversion price from $20.5010 to $25.2320 per share. The Warrants are only exercisable on the applicable expiration dates in accordance with the Warrants. Subject to the other terms of the Warrants, the first expiration date applicable to the Warrants is September 1, 2024, and the final expiration date applicable to the Warrants is April 22, 2025.

During the fourth quarter of 2020, the Company entered into partial unwind agreements to unwind number of warrants exercisable under the note hedge arrangements and to issue approximately 2.1 million Warrants on a net basis, resulting in a net issuance of approximately 1.9 million shares of the Company’s common stock in connection with the exchange of the Notes due 2024. As of December 31, 2020, Warrants exercisable to purchase a total of approximately 4.3 million shares remains outstanding.

Given that the transactions meet certain accounting criteria, the Notes due 2024 hedge and the warrants transactions are recorded in stockholders’ equity, and they are not accounted for as derivatives and are not remeasured each reporting period.

Convertible Senior Notes due 2023

In August 2018, the Company sold $65.0 million aggregate principal amount of 4.0% convertible senior notes due 2023 (the “Notes due 2023”) in a private placement. On May 30, 2019, the Company entered into separately and privately negotiated transactions with certain holders of the Notes due 2023 resulting in the repurchase and exchange, as of June 5, 2019, of $60.0 million aggregate principal amount of the notes in consideration for the issuance of 10,801,080 shares of common stock and separate cash payments totaling $6.0 million. As of both December 31, 2020 and December 31, 2019, $5.0 million aggregate principal amount of the Notes due 2023 remains outstanding.

The remaining outstanding Notes due 2023 are general unsecured obligations and bear interest at a rate of 4.0% per year, payable semi-annually on February 1 and August 1 of each year. The Notes due 2023 are governed by an indenture between the Company and U.S. Bank National Association, as trustee. The remaining outstanding Notes due 2023 will mature on August 1, 2023, unless earlier repurchased by the Company or converted at the option of the holders. The Company may not redeem the remaining Notes due 2023 prior to the maturity date, and no sinking fund is provided for such notes. The remaining Notes due 2023 are convertible, at a holder’s election, in multiples of $1,000 principal amount, into shares of the Company’s common stock based on the applicable conversion rate. The initial conversion rate for such notes is 180.0180 shares of common stock per $1,000 principal amount of notes (which is equivalent to an initial conversion price of approximately $5.56 per share). The conversion rate and the corresponding conversion price are subject to adjustment upon the occurrence of certain events but will not be adjusted for any accrued and unpaid interest. Holders of the remaining Notes due 2023 who convert their notes in connection with a make-whole fundamental change (as defined in the applicable indenture) are, under certain circumstances, entitled to an increase in the conversion rate. Additionally, in the event of a fundamental change, holders of the remaining Notes due 2023 may require the Company to repurchase all or a portion of their notes at a price equal to 100% of the principal amount of notes, plus any accrued and unpaid interest, including any additional interest to, but excluding, the repurchase date. Holders may convert all or any portion of their Notes due 2023 at their option at any time prior to the close of business on the business day immediately preceding the maturity date, in multiples of $1,000 principal amount.

The following table presents the amount of interest cost recognized relating to the contractual interest coupon and the amortization of debt issuance costs of the Notes due 2023.



	Years Ended December 31,
		2020		2019
		(In thousands)
Contractual interest expense		$	200	$	1,226

Amortization of debt issuance costs		40		245
Total interest costs recognized		$	240	$	1,471

Sale of Long-Term Financing Receivables

The Company entered into an agreement with a third party in the fourth quarter of 2017 to sell certain current and future receivables at a discount. In December 2017, the third party made an initial purchase of receivables that resulted in net proceeds to the Company of $2.8 million. This transaction was recorded as debt on the accompanying consolidated balance sheets, and the debt balance was relieved in January 2019 as the underlying receivables were settled. During the year ended December 31, 2018, the third party made three additional purchases of receivables that resulted in total net proceeds to the Company of $5.6 million. These transactions were recorded as debt on the accompanying consolidated balance sheets, and the total associated debt balance will be relieved by September 2021 as the underlying receivables are settled. As of December 31, 2020, the total sale of long-term financing receivable recorded as debt of $1.9 million remains outstanding.

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

Operating Leases

The Company leases office facilities under noncancelable operating leases that expire on various dates through 2031, some of which may include options to extend the leases for up to 12 years.

The components of lease expense are presented as follows:


	Years Ended December 31,
		2020		2019
		(In thousands)
Operating lease costs		$	5,332	$	4,041

The components of lease liabilities are presented as follows:


	December 31, 2020		December 31, 2019
	(In thousands)
Operating lease liabilities, current (Accrued liabilities)	$	4,542	$	3,170
Operating lease liabilities, noncurrent (Other liabilities)	15,209		9,542
Total operating lease liabilities	$	19,751	$	12,712

Supplemental lease information:
Weighted average remaining lease term	6.4 years		5.5 years
Weighted average discount rate	7.7%		8.6%

Supplemental cash flow and other information related to operating leases, are as follows:


	Years Ended December 31,
		2020		2019
		(In thousands)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases		$	4,762	$	3,636

Non-cash investing activities:
Lease liabilities arising from obtaining right-of-use assets		$	10,625	$	4,834

Undiscounted cash flows of operating lease liabilities as of December 31, 2020 are as follows:


	Lease Amounts
	(In thousands)
Year:
2021	$	5,830
2022	4,677
2023	4,056
2024	3,069
2025	2,275
2026 and thereafter	3,968
Total lease payments	23,875
Less: imputed lease interest	(4,124)
Total lease liabilities	$	19,751

Purchase Obligations

The Company has contractual obligations related to component inventory that its contract manufacturers procure on its behalf in accordance with its production forecast as well as other inventory related purchase commitments. As of December 31, 2020, these purchase obligations totaled approximately $162.2 million.

Letter of Credits

As of December 31, 2019, the Company had a standby letter of credit in the aggregate amount of $44.7 million, primarily in connection with one of its customer contracts. The letter of credit served as a performance security for product delivered to the customer in the first quarter of 2020 and expired on April 30, 2020. No amounts were drawn against this letter of credit. As of December 31, 2020, the Company has no letter of credits outstanding.

Litigation

The Company is subject to various legal proceedings relating to claims arising out of its operations that have not been fully resolved. The outcome of litigation is inherently uncertain. If one or more legal matters were resolved against the Company in a reporting period for amounts above management’s expectations, the Company’s business, results of operations, financial position and cash flows for that reporting period could be materially adversely affected. As of February 12, 2021, the Company is not currently a party to any matters that the management expects will have an adverse material effect on the Company’s consolidated financial position, results of operations or cash flows.

Contingencies

On March 26, 2020, the Office of the United States Trade Representative (the “USTR”) announced certain exclusion requests related to tariffs on Chinese imported microinverter products that fit the dimensions and weight limits within a Section 301 Tariff exclusion under U.S. note 20(ss)(40) to subchapter III of chapter 99 of the Harmonized Tariff Schedule of the United States (the “Tariff Exclusion”). The Tariff Exclusion applies to covered products under the China Section 301 Tariff Actions (“Section 301 Tariffs”) taken by the USTR exported from China to the United States from September 24, 2018 until August 7, 2020. Accordingly, the Company has sought refunds totaling approximately $38.9 million plus approximately $0.6 million accrued interest on tariffs previously paid from September 24, 2018 to March 31, 2020 for certain microinverters that qualify for the Tariff Exclusion. The refund request was subject to review and approval by the U.S. Customs and Border Protection; therefore, the Company assessed the probable loss recovery in the year ended December 31, 2020 is equal to the approved refund requests available to us prior to issuance of the financial statements on February 12, 2021.

As of December 31, 2020, the Company had received $24.8 million of tariff refunds and accrued for the remaining $14.7 million tariff refunds that were approved, however, not yet received on or before December 31, 2020. For the year ended December 31, 2020, the Company recorded $38.9 million as a reduction to cost of revenues in the Company’s consolidated statements of operations as the approved refunds relate to paid tariffs previously recorded to cost of revenues, therefore, the Company recorded the corresponding approved tariff refunds as credits to cost of revenues in the current period. For the year ended December 31, 2020, the Company recorded the $0.6 million accrued interest as interest income in the consolidated statement of operations. The tariff refund receivable of $14.7 million is recorded as a reduction of accounts payable to Flex Ltd. and affiliates (“Flex”), the Company’s manufacturing partner and the importer of record who will first receive the tariff refunds, on the Company’s consolidated balance sheet as of December 31, 2020. The Company is unable to predict the timing of receipt of the $14.7 million approved.

The Tariff Exclusion expired on August 7, 2020 and those microinverter products now are subject to tariffs. The Company continues to pay Section 301 Tariffs on its storage and communication products and other accessories imported from China which are not subject to the Tariff Exclusion.

SALE OF COMMON STOCK	12 Months Ended
SALE OF COMMON STOCK	Dec. 31, 2020
Equity [Abstract]
SALE OF COMMON STOCK	SALE OF COMMON STOCKIn February 2018, the Company entered into a Securities Purchase Agreement with an investor pursuant to which the Company, in a private placement, issued and sold to the investor approximately 9.5 million shares of the Company’s common stock at a price per share of $2.10, for gross proceeds of approximately $20.0 million.

STOCK-BASED COMPENSATION

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

STOCK-BASED COMPENSATION

Description of Equity Incentive Plans

2006 Plan

Under the Company’s 2006 Equity Incentive Plan (the “2006 Plan”), equity awards granted generally vest over a 4‑year period from the date of grant with a contractual term of up to 10 years. As of December 31, 2020, there were less than 0.1 million shares of options outstanding under the 2006 Plan. No further stock options or other stock awards may be granted under the 2006 Plan.

2011 Plan

Under the 2011 Equity Incentive Plan (the “2011 Plan”), the Company could initially issue up to 2,643,171 shares of its common stock pursuant to stock options, stock appreciation rights (“SARS”), restricted stock awards (“RSA”), RSUs, PSUs, and other forms of equity compensation, or collectively, stock awards, all of which may be granted to employees, including officers, and to non-employee directors and consultants. Options granted under the 2011 Plan before August 1, 2012 generally expire 10 years after the grant date and options granted thereafter generally expire 7 years after the grant date. Equity awards granted under the 2011 Plan generally vest over a 4-year period from the date of grant based on continued employment. The number of shares of the Company’s common stock authorized for issuance under the 2011 Plan automatically increases on each January 1 by 4.5% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or such lesser number of shares of common stock as determined by the board of directors. As of December 31, 2020, 8,940,388 shares remained available for issuance pursuant to future grants under the 2011 Plan. On January 1, 2021, the shares available for issuance under the 2011 Plan automatically increased by 5,803,296 shares.

2011 Employee Stock Purchase Plan

The 2011 Employee Stock Purchase Plan (“ESPP”) became effective immediately upon the execution and delivery of the underwriting agreement for the Company’s initial public offering on March 29, 2012. The ESPP authorized the issuance of 669,603 shares of the Company’s common stock pursuant to purchase rights granted to employees. The number of shares of common stock reserved for issuance will automatically increase, on each January 1, by a lesser of (i) 330,396 shares of the Company’s common stock or (ii) 1.0% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, as determined by the Company’s board of directors. At the Annual Meeting of Stockholders held on May 18, 2017 the Company’s stockholders approved a one-time amendment to the Company’s ESPP to increase the aggregate number of shares available for purchase by 400,000 shares and to increase the annual automatic minimum increase in shares reserved for issuance from 330,396 to 700,000 shares effective January 1, 2018. As of December 31, 2020, 1,288,887 shares remained available for future issuance under the ESPP. On January 1, 2021, the shares available for issuance under the ESPP automatically increased by 700,000 shares.

The ESPP is implemented by concurrent offering periods and each offering period may contain up to four interim purchase periods. In general, offering periods consist of the 24-month periods commencing on each May 15 and November 15 of a calendar year.

Generally, all full-time employees in Australia, France, India, Mexico, New Zealand, the Netherlands and the United States, including executive officers, are eligible to participate in the ESPP. The ESPP permits eligible employees to purchase the Company’s common stock through payroll deductions, which may not exceed 15% of the employee’s total compensation subject to certain limits. Stock may be purchased under the plan at a price equal to 85% of the fair market value of the Company’s stock on either the date of purchase or the first day of an offering period, whichever is lower. A two‑year look-back feature in the Company’s ESPP causes an offering period to reset if the fair value of the Company’s common stock on a purchase date is less than that on the initial offering date for that offering period. The reset feature, when triggered, will be accounted for as a modification to the original offering, resulting in additional expense to be recognized over the 24-month period of the new offering. During any calendar year, participants may not purchase shares of common stock having a value greater than $25,000, based on the fair market value per share of the common stock at the beginning of an offering period.

Valuation of Equity Awards

Stock Options

The fair value of each option granted was estimated on the date of grant using the Black-Scholes option-pricing model with the following assumptions:

•Expected term - The expected term of the option awards represents the period of time between the grant date of the option awards and the date the option awards are either exercised, converted or canceled, including an estimate for those option awards still outstanding. The Company used the simplified method, as permitted by the SEC for companies with a limited history of stock option exercise activity, to determine the expected term for its option grants.

•Expected volatility - The expected volatility was calculated based on the Company’s historical stock prices, supplemented as necessary with historical volatility of the common stock of several peer companies with characteristics similar to those of the Company.

•Risk-free interest rate - The risk-free interest rate was based on the U.S. Treasury yield curve in effect at the time of grant and with a maturity that approximated the Company’s expected term.

•Dividend yield - The dividend yield was based on the Company’s dividend history and the anticipated dividend payout over its expected term.

The following table presents the weighted-average grant date fair value of options granted for the periods presented and the assumptions used to estimate those values using a Black-Scholes option pricing model.


	Years Ended December 31,
		2020		2019		2018
Weighted average grant date fair value		$	38.45	$	9.16	$	2.83
Expected term (in years)		3.8		3.8		4.0
Expected volatility		86.4%		89.1%		88.5%
Annual risk-free rate of return		0.1%		2.1%		2.6%
Dividend yield		—%		—%		—%

Restricted Stock Units

The fair value of the Company’s restricted stock units (“RSU”) awards granted is based upon the closing price of the Company’s stock price on the date of grant.

Performance Stock Units

The fair value of the Company’s non-market performance stock units (“PSU”) awards granted was based upon the closing price of the Company’s stock price on the date of grant. The fair value of awards of the Company’s PSU awards containing market conditions was determined using a Monte Carlo simulation model based upon the terms of the conditions, the expected volatility of the underlying security, and other relevant factors.

Stock-based Compensation Expense

Stock-based compensation expense for all stock-based awards expected to vest is measured at fair value on the date of grant and recognized ratably over the requisite service period. The following table summarizes the components of total stock-based compensation expense included in the consolidated statements of operations for the periods presented.


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Cost of revenues		$	3,759	$	1,650	$	1,071
Research and development		12,701		4,897		2,940
Sales and marketing		11,548		5,678		3,074
General and administrative		14,495		7,216		4,347
Restructuring		—		735		—
Total		$	42,503	$	20,176	$	11,432
Income tax benefit included in the provision for incomes taxes		$	61,389	$	8,185	$	—

The following table summarizes the various types of stock-based compensation expense for the periods presented.


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Stock options, RSUs, and PSUs		$	39,841	$	19,216	$	10,691
Employee stock purchase plan		2,662		960		741

Total		$	42,503	$	20,176	$	11,432

As of December 31, 2020, there was approximately $89.7 million of total unrecognized stock-based compensation expense related to unvested equity awards, which are expected to be recognized over a weighted-average period of 2.9 years.

Equity Awards Activity

Stock Options

The following is a summary of stock option activity.


	Number of Shares Outstanding	Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value (1)
	(In thousands)			(Years)	(In thousands)
Outstanding at December 31, 2017	8,426	$	1.77
Granted	213	4.43
Exercised	(1,346)	1.75			$	5,096
Canceled	(521)	2.94
Outstanding at December 31, 2018	6,772	$	1.76
Granted	43	14.58
Exercised	(2,616)	1.22			$	31,093
Canceled	(102)	4.07
Outstanding at December 31, 2019	4,097	$	2.18
Granted	11	64.17
Exercised	(1,494)	2.74			$	114,089
Canceled	(82)	6.94
Outstanding at December 31, 2020	2,532	$	1.96	3.7	$	439,268
Vested and expected to vest at December 31, 2020	2,532	$	1.96	3.7	$	439,268
Exercisable at December 31, 2020	2,089	$	1.95	3.7	$	362,526

(1) The intrinsic value of options exercised is based upon the value of the Company’s stock at exercise. The intrinsic value of options outstanding, vested and expected to vest, and exercisable as of December 31, 2020 is based on the closing price of the last trading day during the period ended December 31, 2020. The Company’s stock fair value used in this computation was $175.47 per share.

The following table summarizes information about stock options outstanding at December 31, 2020.


	Options Outstanding				Options Exercisable
Range of Exercise Prices	Number of Shares	Weighted- Average Remaining Life	Weighted- Average Exercise Price		Number of Shares	Weighted- Average Exercise Price
	(In thousands)	(Years)			(In thousands)
$0.70 —– $1.11	555	4.2	$	0.85	448	$	0.83
$1.29 —– $1.29	1,000	3.7	1.29		813	1.29
$1.31 —– $1.31	670	3.3	1.31		587	1.31
$1.37 —– $14.58	296	3.6	5.56		235	6.37
$64.17 —– $64.17	11	6.3	64.17		6	64.17
Total	2,532	3.7	$	1.96	2,089	$	1.95

Restricted Stock Units

The following is a summary of RSU activity.


	Number of Shares Outstanding	Weighted- Average Fair Value per Share at Grant Date		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value (1)
	(In thousands)			(Years)	(In thousands)
Outstanding at December 31, 2017	3,505	$	2.03
Granted	3,152	4.45
Vested	(1,399)	2.75			$	6,657
Canceled	(906)	2.17
Outstanding at December 31, 2018	4,352	$	3.52
Granted	2,112	11.50
Vested	(1,707)	3.87			$	27,156
Canceled	(494)	4.81
Outstanding at December 31, 2019	4,263	$	7.19
Granted	1,550	55.66
Vested	(2,085)	7.26			$	125,578
Canceled	(140)	19.47
Outstanding at December 31, 2020	3,588	$	27.61	1.08	$	629,633
Expected to vest at December 31, 2020	3,588	$	27.61	1.08	$	629,633

(1) The intrinsic value of RSUs vested is based upon the value of the Company’s stock when vested. The intrinsic value of RSUs outstanding and expected to vest as of December 31, 2020 is based on the closing price of the last trading day during the period ended December 31, 2020. The Company’s stock fair value used in this computation was $175.47 per share.

Performance Stock Units

The following is a summary of PSU activity.


	Number of Shares Outstanding	Weighted- Average Fair Value per Share at Grant Date		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value (1)
	(In thousands)			(Years)	(In thousands)
Outstanding at December 31, 2017	—
Granted	1,477	$	4.65
Vested	—
Canceled	(147)
Outstanding at December 31, 2018	1,330	$	4.66
Granted	1,052	9.48
Vested	(1,063)	4.62			10,818
Canceled	(364)	5.16
Outstanding at December 31, 2019	955	$	9.83
Granted	989	31.12
Vested	(1,450)	10.20			$	52,144
Canceled	—	—
Outstanding at December 31, 2020	494	$	51.10	0.2	$	86,668

(1) The intrinsic value of PSUs vested is based upon the value of the Company’s stock when vested. The intrinsic value of PSUs outstanding and expected to vest as of December 31, 2020 is based on the closing price of the last trading day during the period ended December 31, 2020. The Company’s stock fair value used in this computation was $175.47 per share.

Employee Stock Purchase Plan

A summary of ESPP activity for the years presented is as follows: (in thousands, except per share data):


	Years Ended December 31,
	2020		2019		2018
Proceeds from common stock issued under ESPP	$	4,304	$	1,692	$	397
Shares of common stock issued	347		315		439
Weighted-average price per share	$	12.41	$	5.37	$	0.90

INCOME TAXES

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

INCOME TAXES

The domestic and foreign components of income (loss) before income taxes consisted of the following:


	Years Ended December 31,
	2020		2019		2018
	(In thousands)
United States	$	112,727	$	85,520	$	(14,322)
Foreign	6,683		4,594		4,093
Income (loss) before income taxes	$	119,410	$	90,114	$	(10,229)

The income taxes (benefit) provision for the years presented is as follows:


	Years Ended December 31,
	2020		2019		2018
	(In thousands)
Current:
Federal	$	—	$	—	$	—
State	636		327		42
Foreign	1,896		1,589		1,233
	2,532		1,916		1,275
Deferred:
Federal	(13,445)		(56,959)		(35)
State	(3,672)		(17,458)		(21)
Foreign	—		1,467		179
	(17,117)		(72,950)		123
Income taxes (benefit) provision	$	(14,585)	$	(71,034)	$	1,398

A reconciliation of the income tax (benefit) provision and the amount computed by applying the statutory federal income tax rate of 21% to income (loss) before income taxes for the years presented is as follows:


	Years Ended December 31,
	2020		2019		2018
	(In thousands)
Income tax (benefit) provision at statutory federal rate	$	25,076	$	18,929	$	(2,148)
State taxes, net of federal benefit	(3,098)		(17,197)		17
Change in valuation allowance	—		(71,300)		8,198
Foreign tax rate and tax law differential	611		1,206		313
Tax credits	(5,835)		(1,803)		(378)
Stock-based compensation	(50,818)		(8,072)		(953)
Other permanent items	(253)		31		235

Other nondeductible/nontaxable items	1,525		2,765		(5,112)
Uncertain tax positions	1,530		504		107

GILTI	—		1,086		917
Section 162(m)	11,469		2,817		202
Warrant mark-to-mark adjustment	5,208		—		—
Income tax (benefit) provision	$	(14,585)	$	(71,034)	$	1,398

A summary of significant components of the Company’s deferred tax assets and liabilities as of December 31, 2020 and 2019 is as follows (in thousands):


	December 31,
	2020		2019
Deferred tax assets:
Allowances and reserves	$	13,146	$	10,726
Net operating loss and tax credit carryforwards	53,116		54,369
Stock-based compensation	4,598		3,753
Deferred revenue	20,765		16,736
Fixed assets and intangibles	8,706		2,720
Sec. 163(j) interest carryforward	4,401		—
Other	7,007		1,109
Subtotal	111,739		89,413

Total deferred tax assets	111,739		89,413
Deferred tax liabilities:
Goodwill	(1,719)		(1,368)
Unremitted foreign earnings	(7)		(5)
Deferred cost of goods sold	(17,545)		(14,374)
Total deferred tax liabilities	(19,271)		(15,747)
Net deferred tax asset	$	92,468	$	73,666

The Company's accounting for deferred taxes involves the evaluation of a number of factors concerning the realizability of the Company's deferred tax assets. Assessing the realizability of deferred tax assets is dependent upon several factors, including the likelihood and amount, if any, of future taxable income in relevant jurisdictions during the periods in which those temporary differences become deductible. The Company's management forecasts taxable income by considering all available positive and negative evidence including its history of operating income or losses and its financial plans and estimates which are used to manage the business. These assumptions require significant judgment about future taxable income. The amount of deferred tax assets considered realizable is subject to adjustment in future periods if estimates of future taxable income are reduced.

The Company has net operating loss carryforwards for federal and California income tax purposes of approximately $113.7 million and $87.3 million, respectively, as of December 31, 2020. The federal and state net operating loss carryforwards, if not utilized, will expire beginning in 2036 and 2029, respectively.

The Company has approximately $18.2 million of federal research credit and $12.6 million of state research credit carryforwards. The federal credits begin to expire in 2026 and the state credits can be carried forward indefinitely.

Utilization of some of the federal and state net operating loss and credit carryforwards are subject to annual limitations due to the “change in ownership” provisions of the Internal Revenue Code of 1986 and similar state provisions. The Company has completed a Section 382 analysis through December 31, 2020, which indicated no such change has occurred through December 31, 2020.

The accounting for uncertain tax positions prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The Company is required to recognize in the financial statements the impact of a tax position, if that position is more-likely-than-not of being sustained on audit, based on the technical merits of the position. The Company recorded a net charge for unrecognized tax benefits in 2020 of $1.8 million.

The Company does not have any tax positions for which it is reasonably possible the total amount of gross unrecognized tax benefits will increase or decrease over the next year. The unrecognized tax benefits may increase or change during the next year for items that arise in the ordinary course of business.

A tabular reconciliation of the total amounts of unrecognized tax benefits for the years presented is as follows (in thousands):


	Years Ended December 31,
	2020		2019		2018
Unrecognized tax benefits—at beginning of year	$	6,589	$	6,325	$	6,106

Decreases in balances related to tax positions taken in prior years	—		(370)		—
Increases in balances related to tax positions taken in current year	2,006		771		329

Lapses in statutes of limitations	(174)		(137)		(110)
Unrecognized tax benefits—at end of year	$	8,421	$	6,589	$	6,325

The Company includes interest and penalties related to unrecognized tax benefits within the benefit from (provision for) income taxes. As of years ended December 31, 2020, 2019 and 2018, the total amount of gross interest and penalties accrued in each year was immaterial. Both the unrecognized tax benefits and the associated interest and penalties that are not expected to result in payment or receipt of cash within one year are classified as other non-current liabilities in the consolidated balance sheets. In connection with tax matters, the Company’s interest and penalty expense recognized in 2020, 2019 and 2018 in the consolidated statements of operations was immaterial.

The Company’s tax returns continue to remain effectively subject to examination by U.S. federal authorities for the years 2006 through 2020 and by California state authorities for the years 2006 through 2020 due to use and carryovers of net operating losses and credits.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS	12 Months Ended
CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS	Dec. 31, 2020
Risks and Uncertainties [Abstract]
CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS	CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS The Company is potentially subject to financial instrument concentration of credit risk through its cash and cash equivalents and accounts receivable. The Company places its cash and cash equivalents with high quality institutions and performs periodic evaluations of their relative credit standing. Accounts receivable can be potentially exposed to a concentration of credit risk with its major customers. As of December 31, 2020, amounts due from one customer represented approximately 36% of the total accounts receivable balance. As of December 31, 2019, amounts due from three customers represented 34%, 14% and 11% of the total accounts receivable balance. In 2020, one customer accounted for approximately 29% of total net revenues. In 2019, two customers accounted for approximately 21% and 12% of total net revenues. In 2018, one customer accounted for approximately 19% of total net revenues.

NET INCOME (LOSS) PER SHARE

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

NET INCOME (LOSS) PER SHARE

Basic net income (loss) per share is computed by dividing net income (loss) by the weighted average number of shares of common stock outstanding during the period. Diluted net income (loss) per share is computed in a similar manner, but it also includes the effect of potential common shares outstanding during the period, when dilutive. Potential common shares include Stock Options, RSUs, PSUs, shares to be purchased under the Company’s ESPP, the Notes due 2023, the Notes due 2024, Warrants issued in conjunction with the Notes due 2024, and from May 20, 2020 to the end of the reporting period, the Notes due 2025 and Warrants issued in conjunction with the Notes due 2025. See Note 11. “Debt” for additional information.

The dilutive effect of potentially dilutive common shares is reflected in diluted earnings per share by application of the treasury stock method for stock options, RSUs, PSUs, Notes due 2024, warrants issued in conjunction with the Notes due 2024, Notes due 2025, warrants issued in conjunction with the Notes due 2025 and shares to be purchased under the ESPP, and by application of the if-converted method for the Notes due 2023. To the extent these potential common shares are antidilutive, they are excluded from the calculation of diluted net income (loss) per share.

The following table presents the computation of basic and diluted net income (loss) per share for the periods presented.


	Years Ended December 31,
		2020		2019		2018
		(In thousands, except per share data)
Numerator:
Net income (loss)		$	133,995	$	161,148	$	(11,627)
Notes due 2023 interest and financing costs, net		177		1,088		—
Adjusted net income (loss)		$	134,172	$	162,236	$	(11,627)

Denominator:
Shares used in basic per share amounts:
Weighted average common shares outstanding		125,561		116,713		99,619

Shares used in diluted per share amounts:
Weighted average common shares outstanding		125,561		116,713		99,619
Effect of dilutive securities:
Employee stock-based awards		6,997		8,964		—

Warrants (issued in conjunction with Notes due 2024)		4,011		—		—

Notes due 2024		4,449		451		—
Notes due 2023		900		5,516		—
Weighted average common shares outstanding for diluted calculation		141,918		131,644		99,619

Basic and diluted net income (loss) per share
Net income (loss) per share, basic		$	1.07	$	1.38	$	(0.12)
Net income (loss) per share, diluted		$	0.95	$	1.23	$	(0.12)

The following outstanding shares of common stock equivalents were excluded from the calculation of the diluted net income (loss) per share attributable to common stockholders because their effect would have been antidilutive.


	Years Ended December 31,
		2020	2019	2018
		(In thousands)
Employee stock options		7	27	7,710
RSUs and PSUs		36	158	5,273



Warrants (issued in conjunction with Notes due 2024)		—	300	—


Warrants (issued in conjunction with Notes due 2025)		1,254	—	—
Notes due 2025		197	—
Notes due 2023		—	—	11,701
Total		1,494	485	24,684

Diluted earnings per share for the year ended December 31, 2020 includes the dilutive effect of stock options, RSUs, PSUs, shares to be purchased under the ESPP, the Notes due 2023, the Notes due 2024, and warrants issued in conjunction with the Notes due 2024. Certain common stock issuable under stock options, RSUs, PSUs, Notes due 2025 and warrants issued in conjunction with the Notes due 2025 have been omitted from the diluted net income per share calculation because including such shares would have been antidilutive.

Diluted earnings per share for the year ended December 31, 2019 includes the dilutive effect of stock options, RSUs, PSUs, shares to be purchased under the ESPP, the Notes due 2023 and Notes due 2024. Certain common stock issuable under stock options, RSUs, PSUs and warrants issued in conjunction with the Notes due 2024 have been omitted from the diluted net income per share calculation because including such shares would have been antidilutive.Since the Company has the intent and ability to settle the aggregate principal amount of the Notes due 2024 and Notes due 2025 in cash and any excess in shares of the Company’s common stock, the Company uses the treasury stock method for calculating any potential dilutive effect of the conversion spread on diluted net income per share, if applicable. In order to compute the dilutive effect, the number of shares included in the denominator of diluted net income per share is determined by dividing the conversion spread value of the “in-the-money” Notes due 2024 and Notes due 2025 by the Company’s average share price during the period and including the resulting share amount in the diluted net income per share denominator. The conversion spread will have a dilutive impact on net income per share of common stock when the average market price of the Company’s common stock for a given period exceeds the conversion price of $20.50 per share and $81.54 per share for the Notes due 2024 and Notes due 2025, respectively.

SEGMENT AND GEOGRAPHIC INFORMATION

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

SEGMENT AND GEOGRAPHIC INFORMATION

The Company’s chief operating decision maker is the Chief Executive Officer. The Chief Executive Officer reviews financial information presented on a consolidated basis. The Company has one business activity, which entails the design, development, manufacture and sale of solutions for the solar photovoltaic industry. There are no segment managers who are held accountable for operations, operating results or plans for levels or components below the consolidated unit level. Accordingly, management has determined that the Company has a single operating and reportable segment.

See Note 3. “Revenue Recognition for the table presenting net revenues (based on the destination of shipments). The following table presents long-lived assets by geographic region as of and for the periods presented (in thousands):

Long-Lived Assets


	December 31,
	2020		2019
	(In thousands)
United States	$	19,870	$	16,754
China	9,948		4,635
Mexico	4,808		3,510
India	4,371		1,315
New Zealand	3,837		2,638
Other	151		84
Total	$	42,985	$	28,936

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8981-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8721-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8657-108599

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8721-108599

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-URI http://asc.fasb.org/topic&trid=2134510

+ Details

RELATED PARTY	12 Months Ended
RELATED PARTY	Dec. 31, 2020
Related Party Transactions [Abstract]
RELATED PARTY	RELATED PARTYIn 2018, a member of the Company’s board of directors and one of its principal stockholders, Thurman John Rodgers, purchased $5.0 million aggregate principal amount of the Notes due 2023 in a concurrent private placement. As of both December 31, 2020 and December 31, 2019, $5.0 million aggregate principal amount of the Notes due 2023 were outstanding. See Note 11. “Debt” for additional information related to this purchase. The Company sells products to SunPower under the August 2018 MSA. As of December 31, 2019, SunPower via its wholly owned subsidiary, held 6.5 million shares of the Company’s common stock. Revenue recognized under the MSA for the year ended December 31, 2019 was $70.9 million, net of amortization of the customer relationship intangible asset (see Note 6. “Goodwill and Intangible Assets”). As of December 31, 2019, the Company had accounts receivable of $15.9 million from SunPower. As of December 31, 2019, the Company received $5.2 million as a safe harbor prepayment from SunPower in the fourth quarter of 2019 for product delivered in the first quarter of 2020. As of December 31, 2020, SunPower via its wholly owned subsidiary held 3.5 million shares of the Company’s common stock which is less than 5% of the Company’s common stock outstanding and is no longer a considered a related party.

ACQUISITION

12 Months Ended

Dec. 31, 2020

Business Combinations [Abstract]

ACQUISITION

On August 9, 2018, the Company completed its acquisition of SunPower’s microinverter business pursuant to an APA by which the Company acquired certain assets and liabilities of SunPower relating to the research and development and manufacturing of microinverters. The acquisition was accounted for as a business combination and, accordingly, the total purchase price was allocated to the preliminary net tangible and intangible assets and liabilities based on their preliminary fair values on the acquisition date.

In conjunction with the APA, the Company entered into an MSA with SunPower. Pursuant to the terms of the MSA, the Company becomes the exclusive supplier of MLPEs for SunPower’s residential business in the U.S. for a period of five years. The resulting customer relationship intangible is accounted for as a distinct transaction from the acquired business.

The acquisition date fair value of the consideration transferred was approximately $57.3 million, which consisted of the following (in thousands):


Cash consideration	$	25,000
Common stock issued	32,319
Total	$	57,319

The fair value of the Company’s 7.5 million shares of common stock issued, valued at $32.3 million, was determined based on the closing market price of the Company’s common stock on the acquisition date, less a discount of 14% to 30% (depending on the year) for lack of marketability as the shares issued are subject to a restriction that limits their trade or transfer with a lock-up period of six months and restrictions on the number of shares that can be transferred by SunPower in each six-month period following the lock-up period.

The following table summarizes the preliminary estimated fair values of the assets acquired and liabilities assumed at the acquisition date (in thousands):



Intangible assets	$	36,200
Goodwill	21,119
Net assets acquired	$	57,319

The excess of the consideration paid over the fair values assigned to the assets acquired and liabilities assumed represents the goodwill resulting from the acquisition. The $21.1 million of goodwill recognized is attributable primarily to the benefits the Company expects to derive from enhanced scale and efficiency to better serve its markets. Goodwill is expected to be deductible over the next 15 years for income tax purposes.

The fair values assigned to tangible and identifiable intangible assets acquired are based on management’s estimates and assumptions. The fair values of assets acquired are preliminary and may be subject to change within the measurement period as the fair value assessments are finalized.

The following table shows the fair value of the separately identifiable intangible assets at the time of acquisition and the period over which each intangible asset will be amortized:


	Preliminary Fair Value		Useful Life
	(In thousands)		(Years)
Developed technology	$	13,100	6
Customer relationship	23,100		9
Total identifiable intangible assets	$	36,200

The developed technology acquired is embedded in the microinverters that SunPower sells to its customers. The Company already has developed microinverter technology and the Company will supply its microinverters to SunPower through the term of the MSA. The Company does not intend to actively use the developed technology acquired from SunPower but does plan to hold the developed technology to prevent others from using it. Therefore, the Company will account for the developed technology as a defensive intangible asset. The Company expects to realize the benefits of the developed technology over the period of time in which the Company will supply microinverters to SunPower. The Company does expect changes in microinverter technology during the life of the customer relationship with SunPower and expects to benefit from preventing competitors’ access to the technology over a period of six years, therefore, the Company will amortize the value of the developed technology intangible asset over a period of six years.

The MSA was negotiated together with the APA and provides the Company with the exclusive right to supply SunPower with MLPEs for a period of five years, with options for renewals. The exclusivity arrangement extends throughout the term of the MSA, which comprises all of the expected cash flows from the customer relationship intangible asset, and was a condition to, and was an essential part of the acquisition of the microinverter business by the Company. As the fair value ascribed to the customer relationship intangible asset represents payments to a customer, the Company will amortize the value of the customer relationship intangible asset as a reduction to revenue using a pattern of economic benefit method over a useful life of nine years.

The table below shows estimated fair values of the assets acquired funded by cash and issuance of common stock at the acquisition date:


	Cash Purchase Price		Issuance of Common Stock		Total Consideration		% of Total Consideration
	(In thousands)
Developed technology and goodwill	$	15,000	$	19,219	$	34,219	60	%
Customer relationship	10,000		13,100		23,100		40	%
Total consideration	$	25,000	$	32,319	$	57,319	100	%

The Company allocated $10.0 million of the $25.0 million paid of the cash purchase price to cash flows from operating activities and the remaining $15.0 million to cash used in investing activities in the consolidated statements of cash flows for the year ended December 31, 2018. The allocation was based on the valuation of the customer relationship relative to the overall consideration. In addition, the Company disclosed $19.2 million from issuance of common stock and $15.0 million of cash purchase price paid for the developed technology and goodwill as investing activities in the consolidated statements of cash flows for the year ended December 31, 2018.

During 2018, total acquisition-related costs were approximately $0.8 million, which were included in general and administrative expenses.

The Company determined it is impractical to include such pro forma information given the difficulty in obtaining the historical financial information for the SunPower microinverter business as the business was part of SunPower and did not have discrete financial information prior to the acquisition. Inclusion of such information would require the Company to make estimates and assumptions regarding the acquired business historical financial results that the Company believes may ultimately prove inaccurate.

SUBSEQUENT EVENTS	12 Months Ended
SUBSEQUENT EVENTS	Dec. 31, 2020
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS In January 2021, the Company invested $25.0 million in cash in a privately-held company. The investment does not require consolidation into the Company’s financial statements because the privately-held company is not a variable interest entity and the Company does not hold a majority voting interest. On January 25, 2021, the Company completed the acquisition of 100% of the voting interest of Sofdesk Inc. (“Sofdesk”), a privately-held company. Sofdesk provides design software for residential solar installers and roofing companies. As part of the consideration, the Company paid approximately $32.0 million in cash on January 25, 2021. The Company is currently in the process of completing the preliminary purchase price allocation, which will be included in the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2021. On February 8, 2021, the Company announced that it has agreed to acquire the solar design services business of DIN Engineering Services LLP (“DIN”). DIN provides proposal drawings and permit plan sets for residential solar installers in North America. The acquisition is subject to customary closing conditions and regulatory approvals.

SELECTED UNAUDITED QUARTERLY FINANCIAL INFORMATION

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

SELECTED UNAUDITED QUARTERLY FINANCIAL INFORMATION

The following tables show a summary of the Company’s quarterly financial information for each of the four quarters of 2020 and 2019 (in thousands, except per share data):


	Three Months Ended
	March 31, 2020		June 30, 2020		September 30, 2020		December 31, 2020
Net revenues	$	205,545	$	125,538	$	178,503	$	264,839
Cost of revenues	124,870		77,151		83,522		142,901
Gross profit	80,675		48,387		94,981		121,938
Operating expenses:
Research and development	11,876		13,192		15,052		15,801
Sales and marketing	11,772		12,371		14,645		14,139
General and administrative	12,315		11,970		13,525		12,884

Total operating expenses	35,963		37,533		43,222		42,824
Income from operations	44,712		10,854		51,759		79,114
Other income (expense), net
Interest Income	1,091		282		110		673
Interest expense	(3,155)		(5,952)		(5,993)		(5,901)
Other income (expense)	(924)		653		(1,031)		(2,534)
Change in fair value of derivatives	15,344		(59,692)		—		—
Total other income (expense), net	12,356		(64,709)		(6,914)		(7,762)



Income (loss) before income taxes	57,068		(53,855)		44,845		71,352
Income tax benefit (provision)	11,868		6,561		(5,483)		1,639
Net income (loss)	$	68,936	$	(47,294)	$	39,362	$	72,991
Net income (loss) per share, basic	$	0.56	$	(0.38)	$	0.31	$	0.57
Net income (loss) per share, diluted	$	0.50	$	(0.38)	$	0.28	$	0.50


	Three Months Ended
	March 31, 2019		June 30, 2019		September 30, 2019		December 31, 2019
Net revenues	$	100,150	$	134,094	$	180,057	$	210,032
Cost of revenues	66,811		88,775		115,351		132,151
Gross profit	33,339		45,319		64,706		77,881
Operating expenses:
Research and development	8,524		9,604		11,085		11,168
Sales and marketing	7,433		9,054		9,551		10,690
General and administrative	9,880		8,583		9,895		10,450
Restructuring charges	368		631		469		1,131
Total operating expenses	26,205		27,872		31,000		33,439
Income from operations	7,134		17,447		33,706		44,442
Other expense, net
Interest income	211		593		894		815
Interest expense	(3,751)		(1,351)		(2,286)		(2,303)
Other income (expense), net	(481)		(5,480)		(943)		1,467
Total other expense, net	(4,021)		(6,238)		(2,335)		(21)


Income before income taxes	3,113		11,209		31,371		44,421
Income tax benefit (provision)	(348)		(591)		(272)		72,245
Net income	$	2,765	$	10,618	$	31,099	$	116,666
Net income per share, basic	$	0.03	$	0.09	$	0.25	$	0.95
Net income per diluted share	$	0.02	$	0.08	$	0.23	$	0.88

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying consolidated financial statements are presented in accordance with accounting principles generally accepted in the United States (“U.S.”), or GAAP. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Significant estimates and assumptions reflected in the financial statements include revenue recognition, allowance for doubtful accounts, stock-based compensation, inventory valuation, accrued warranty obligations, fair value of debt derivatives and convertible notes, fair value of acquired intangible assets and goodwill, useful lives of acquired intangible assets and property and equipment, incremental borrowing rate for right-of-use assets and lease liability, probable loss recovery of tariff refunds, legal contingencies, and tax valuation allowance. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ materially from management’s estimates using different assumptions or under different conditions. The worldwide spread of the COVID-19 virus has resulted in a global slowdown of economic activity which decreased demand for a broad variety of goods and services, including from our customers, while also disrupting sales channels and marketing activities for an unknown period of time and may continue to create significant uncertainty in future operational and financial performance. The Company expects this to have negative impact on its sales and its results of operations. In preparing the Company’s consolidated financial statements in accordance with GAAP, the Company is required to make estimates, assumptions and judgments that affect the amounts reported in its financial statements and the accompanying disclosures. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgment. As of the date of issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, judgments or revise the carrying value of its assets or liabilities. These estimates may change, as new events occur and additional information is obtained, and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s financial statements.
Revenue Recognition, Cost of Revenues and Contract Liabilities	Revenue Recognition The Company generates revenue from sales of its solutions, which include microinverter units and related accessories, an Envoy communications gateway, the cloud-based Enlighten monitoring service, and storage solutions to distributors, large installers, original equipment manufacturers (“OEMs”) and strategic partners. On January 1, 2018, the Company adopted Accounting Standards Codification (“ASC”) No. 606, “Revenue Recognition” (“ASC 606” or “Topic 606”) and applied the modified retrospective method to all contracts that were not completed as of January 1, 2018. The most significant impacts upon adoption of Topic 606 were how the Company accounts for revenue related to its Envoy™ communications device and related Enphase Enlighten Software™, or Enlighten, service and the timing of when certain sales incentives are recognized. The full consideration for these products represents a single performance obligation and is deferred and recognized over the estimated service period. Revenues are recognized when control of the promised goods or services are transferred to the Company’s customers in an amount that reflects the consideration that is expected to be received in exchange for those goods or services. The Company generates all of its revenues from contracts with its customers. A description of principal activities from which the Company generates revenues follows. •Products Delivered at a Point in Time. The Company sells its products to customers in accordance with the terms of the related customer contracts. The Company generates revenues from sales of its solutions, which include microinverter units and related accessories, an Envoy communications gateway and Enlighten service, communications accessories and storage solutions to distributors, large installers, OEMs and strategic partners. Microinverter units, microinverter accessories, and storage solutions are delivered to customers at a point in time, and the Company recognizes revenue for these products when the Company transfers control of the product to the customer, which is generally upon shipment. •Products Delivered Over Time. The sale of an Envoy communications gateway includes the Company’s Enlighten cloud-based monitoring service. The full consideration for these products represents a single performance obligation and is deferred at the sale date and recognized over the estimated service period of 6 years. The Company also sells certain communication accessories that contain a service performance obligation to be delivered over time. The revenue from these products is recognized over the related service period, which is typically 5 or 12 years. When the Company sells a product with more than one performance obligation, such as the IQ Combiner which includes both hardware and Envoy, the total consideration is allocated to these performance obligations based on their relative standalone selling prices. The Company previously sold its Envoy communications device to certain customers under a long-term financing arrangement. Under this financing arrangement, the Company nets the unbilled receivables against deferred revenue. The Company records certain contra revenue promotions as variable consideration and recognizes these promotions at the time the related revenue is recorded. The Company records upfront contract acquisition costs, such as sales commissions, to be capitalized and amortized over the estimated life of the asset. For contracts that have a duration of less than one year, the Company follows the Topic 606 practical expedient and expenses these costs when incurred. Commissions related to the Company’s sale of monitoring hardware and service are capitalized and amortized over the period of the associated revenue, which is 6 years. See Note 3. “Revenue Recognition,” for additional information related to revenue recognition. Cost of Revenues The Company includes the following in cost of revenues: product costs, warranty, manufacturing personnel and logistics costs, freight costs, inventory write-downs, hosting services costs related to the Company’s Enlighten service offering, and depreciation and amortization of manufacturing test equipment. A description of principal activities from which the Company recognizes cost of revenue is as follows. • Products Delivered at a Point in Time. Cost of revenue from these products is recognized when the Company transfers control of the product to the customer, which is generally upon shipment. •Products Delivered Over Time. Cost of revenue from these products is recognized over the related service period. Contract Liabilities Contract liabilities are recorded as deferred revenue on the accompanying consolidated balance sheets and include payments received in advance of performance obligations under the contract and are realized when the associated revenue is recognized under the contract.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents The Company considers all highly liquid investments, such as certificates of deposit and money market instruments with maturities of three months or less at the time of acquisition to be cash equivalents. For all periods presented, its cash balances consist of amounts held in non-interest-bearing and interest-bearing deposits and money market accounts. Restricted Cash Restricted cash represents cash held as certificate of deposit collateralized under a letter of credit issued to a customer. The letter of credit was required as a performance security in a face amount equal to the aggregate purchase price of the executed sales agreement. The letter of credit was issued per the terms of the executed sales agreement with a customer for safe harbor prepayment and the Company had collateralized a certificate of deposit under this letter of credit in an amount of $44.7 million, which was reflected as restricted cash on the Company’s consolidated balance sheet as of December 31, 2019. As of December 31, 2020, the Company does not have restricted cash balance.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The fair value of a financial instrument is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The carrying amounts of the Company’s cash, cash equivalents and restricted cash, accounts receivable, accounts payable and accrued liabilities approximate fair value because of the short maturity of those instruments. Equity investments with readily determinable fair value are carried at fair value based on quoted market prices or estimated based on market conditions and risks existing at each balance sheet date. Equity investments without readily determinable fair value are measured at cost less impairment, and are adjusted for observable price changes in orderly transactions for an identical or similar investment of the same issuer.
Accounts Receivables and Contract Assets	Accounts Receivables and Contract Assets The Company receives payments from customers based upon contractual billing schedules. Accounts receivable are recorded when the right to consideration becomes unconditional. Contract assets include deferred product costs and commissions associated with the deferred revenue and will be amortized along with the associated revenue.
Allowance for Doubtful Accounts	Allowance for Doubtful AccountsThe Company maintains allowances for doubtful accounts for uncollectible accounts receivable. Management estimates anticipated credit losses from doubtful accounts based on days past due, customer specific experience, collection history, the financial health of customers including from the impacts of the COVID-19 pandemic, among other factors. Accounts receivable are recorded net of allowance for doubtful accounts.
Inventory	Inventory Inventory is valued at the lower of cost or market. Market is current replacement cost (by purchase or by reproduction, dependent on the type of inventory). In cases where market exceeds net realizable value (i.e., estimated selling price less reasonably predictable costs of completion and disposal), inventories are stated at net realizable value. Market is not considered to be less than net realizable value reduced by an allowance for an approximately normal profit margin. The Company determines cost on a first-in first-out basis. Management assesses the valuation on a quarterly basis and writes down the value for any excess and obsolete inventory based upon expected demand, anticipated sales price, effect of new product introductions, product obsolescence, customer concentrations, product merchantability and other factors. Inventory write-downs are equal to the difference between the cost of inventories and market.
Property and Equipment	Property and equipment are stated at cost less accumulated depreciation. Cost includes amounts paid to acquire or construct the asset as well as any expenditure that substantially adds to the value of or significantly extends the useful life of an existing asset. Repair and maintenance costs are expensed as incurred. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets, which range from 3 to 10 years. Leasehold improvements are amortized over the shorter of the lease term or expected useful life of the improvements.
Internal-Use Software	Internal-use software, whether purchased or developed, is capitalized at cost and amortized on a straight-line basis over its estimated useful life. Costs associated with internally developed software are expensed until the point at which the project has reached the development stage. Subsequent additions, modifications or upgrades to internal-use software are capitalized only to the extent that they provide additional functionality. Software maintenance and training costs are expensed in the period in which they are incurred. The capitalization of internal-use software requires judgment in determining when a project has reached the development stage and the period over which the Company expects to benefit from the use of that software. The Company capitalizes implementation costs related to cloud computing (i.e. hosting) arrangements that are accounted for as a service contract that meets the accounting requirement for capitalization as such implementation costs were incurred to develop or utilize internal-use software hosted by a third party vendor. The capitalized implementation costs are recorded as part of “Other assets” on the consolidated balance sheet and is amortized over the length of the service contract.
Impairment of Long-Lived Assets	Property, plant and equipment, including internal-use software, and capitalized implementation costs related to cloud computing arrangements, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset (asset group) may not be recoverable. An impairment loss would be recognized when the carrying amount of an asset exceeds the estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition. The amount of the impairment loss to be recorded is calculated by the excess of the asset’s carrying value over its fair value. Fair value is generally determined using a discounted cash flow analysis.
Business Combinations	Business Combinations Assets acquired and liabilities assumed as part of a business acquisition are generally recorded at their fair value at the date of acquisition. The excess of purchase price over the fair value of assets acquired and liabilities assumed is recorded as goodwill. Determining fair value of identifiable assets, particularly intangibles, and liabilities acquired also requires the Company to make estimates, which are based on all available information and in some cases assumptions with respect to the timing and amount of future revenues and expenses associated with an asset. Accounting for business acquisitions requires the Company to make judgments as to whether a purchase transaction is a multiple element contract, meaning that it includes other transaction components. This judgment and determination affect the amount of consideration paid that is allocable to assets and liabilities acquired in the business purchase transaction.
Goodwill and Intangible Assets	Goodwill Goodwill results from the purchase consideration paid in excess of the fair value of the net assets recorded in connection with a business acquisition. Goodwill is not amortized but is assessed for potential impairment at least annually during the fourth quarter of each fiscal year or between annual tests if an event occurs or circumstances change that would indicate the carrying amount may be impaired. Goodwill is tested at the reporting unit level, which the Company has determined to be the same as the entity as a whole (entity level). The Company first performs qualitative assessment to determine whether it is more likely than not that the fair value of our reporting unit is less than its carrying value. If, after assessing the qualitative factors, we determine that it is more likely than not that the fair value of our reporting unit is less than its carrying value, an impairment analysis will be performed. Qualitative factors include industry and market consideration, overall financial performance, share price trends and market capitalization and Company-specific events. The Company determined, after performing a qualitative review of its reporting unit, that it is more likely than not that the fair value of our reporting unit exceeds its carrying value. Accordingly, there was no indication of impairment in the years ended 2020, 2019 and 2018 and no quantitative goodwill impairment test was performed. Intangible Assets Intangible assets include patents and other purchased intangible assets. Intangible assets with finite lives are amortized on a straight-line basis, with estimated useful lives ranging from 3 to 9 years. Indefinite-lived intangible assets are tested for impairment annually and are also tested for impairment between annual tests if an event occurs or circumstances change that would indicate that the carrying amount may be impaired. Intangible assets with finite lives are tested for impairment whenever events or circumstances indicate that the carrying amount of an asset (asset group) may not be recoverable. An impairment loss is recognized when the carrying amount of an asset exceeds the estimated undiscounted cash flows used in determining the fair value of the asset. The amount of the impairment loss to be recorded is calculated by the excess of the asset’s carrying value over its fair value. Fair value is generally determined using a discounted cash flow analysis. There was no impairment of intangible assets in any of the years presented.
Warranty Obligations	Warranty Obligations Microinverters and Other Products Sold Through December 31, 2013 The Company’s warranty accrual provides for the replacement of microinverter units or other products that fail during the product’s warranty term (typically 15 years for first and second generation microinverters and up to 25 years for subsequent generation microinverters). On a quarterly basis, the Company employs a consistent, systematic and rational methodology to assess the adequacy of its warranty liability. This assessment includes updating all key estimates and assumptions for each generation of product, based on historical results, trends and the most current data available as of the filing date. The key estimates and assumptions used in the warranty liability are thoroughly reviewed by management on a quarterly basis. The key estimates used by the Company to estimate its warranty liability are: (1) the number of units expected to fail over time (i.e., failure rate); (2) the number of failed units expected to result in warranty claims over time (i.e., claim rate); and (3) the per unit cost of replacement units, including outbound shipping and limited labor costs, expected to be incurred to replace failed units over time (i.e., replacement cost). Estimated Failure Rates — The Company’s Quality and Reliability department has primary responsibility to determine the estimated failure rates for each generation of microinverter. To establish initial failure rate estimates for each generation of microinverter, the Company’s quality engineers use a combination of industry standard Mean Time Between Failure (“MTBF”) estimates for individual components contained in its microinverters, third party data collected on similar equipment deployed in outdoor environments similar to those in which the Company’s microinverters are installed, and rigorous long term reliability and accelerated life cycle testing which simulates the service life of the microinverter in a short period of time. As units are deployed into operating environments, the Company continues to monitor product performance through its Enlighten monitoring platform. It typically takes three to nine months between the date of sale and date of end-user installation. Consequently, the Company’s ability to monitor actual failures of units sold similarly lags by three to nine months. When a microinverter fails and is returned, the Company performs diagnostic root cause failure analysis to understand and isolate the underlying mechanism(s) causing the failure. The Company then uses the results of this analysis (combined with the actual, cumulative performance data collected on those units prior to failure through Enlighten) to draw conclusions with respect to how or if the identified failure mechanism(s) will impact the remaining units deployed in the installed base. Estimated Claim Rates — Warranty claim rate estimates are based upon observed historical trends and assumptions with respect to expected customer behavior over the warranty period. As the vast majority of the Company’s microinverters have been sold to end users for residential applications, the Company believes that warranty claim rates will be affected by changes over time in residential home ownership because the Company expects that subsequent homeowners are less likely to file claims than the homeowners who originally purchase the microinverters. Estimated Replacement Costs — Three factors are considered in the Company’s analysis of estimated replacement cost: (1) the estimated cost of replacement microinverters; (2) the estimated cost to ship replacement microinverters to end users; and (3) the estimated labor reimbursement expected to be paid to third party installers performing replacement services for the end user. Because the Company’s warranty provides for the replacement of defective microinverters over long periods of time (between 15 and 25 years, depending on the generation of product purchased), the estimated per unit cost of current and future product generations is considered in the estimated replacement cost. Estimated costs to ship replacement units are based on observable, market-based shipping costs paid by the Company to third party freight carriers. The Company has a separate program that allows third-party installers to claim fixed-dollar reimbursements for labor costs they incur to replace failed microinverter units for a limited time from the date of original installation. Included in the Company’s estimated replacement cost is an analysis of the number of fixed-dollar labor reimbursements expected to be claimed by third party installers over the limited offering period. In addition to the key estimates noted above, the Company also compares actual warranty results to expected results and evaluates any significant differences. Management may make additional adjustments to the warranty provision based on performance trends or other qualitative factors. If actual failure rates, claim rates, or replacement costs differ from the Company’s estimates in future periods, changes to these estimates may be required, resulting in increases or decreases in the Company’s warranty obligations. Such increases or decreases could be material. Fair Value Option for Microinverters and Other Products Sold Since January 1, 2014 The Company’s warranty obligations related to microinverters sold since January 1, 2014 provide the Company the right, but not the requirement, to assign its warranty obligations to a third-party. Under ASC 825, “Financial Instruments” (also referred to as “fair value option”), an entity may choose to elect the fair value option for such warranties at the time it first recognizes the eligible item. The Company made an irrevocable election to account for all eligible warranty obligations associated with microinverters sold since January 1, 2014 at fair value. This election was made to reflect the underlying economics of the time value of money for an obligation that will be settled over an extended period of up to 25 years. The Company estimates the fair value of warranty obligations by calculating the warranty obligations in the same manner as for sales prior to January 1, 2014 and applying an expected present value technique to that result. The expected present value technique, an income approach, converts future amounts into a single current discounted amount. In addition to the key estimates of failure rates, claim rates and replacement costs, the Company used certain inputs that are unobservable and significant to the overall fair value measurement. Such additional assumptions included compensation comprised of a profit element and risk premium required of a market participant to assume the obligation and a discount rate based on the Company’s credit-adjusted risk-free rate. See Note 9. “Fair Value Measurements,” for additional information. Warranty obligations initially recorded at fair value at the time of sale will be subsequently re-measured to fair value at each reporting date. In addition, the fair value of the liability will be accreted over the corresponding term of the warranty of up to 25 years using the interest method. Warranty for Other Products The Company offers a 5‑year warranty for its Envoy communications gateway and a 10‑year warranty on its AC Battery storage solution. The warranties provide the Company with the right, but not the obligation, to assign its warranty obligations to a third-party. As such, warranties for Envoy and AC Battery storage solution products are accounted for under the fair value method of accounting.
Commitments and Contingencies	Commitments and Contingencies In the normal course of business, the Company is subject to loss contingencies and loss recoveries, such as legal proceedings and claims arising out of its business as well as tariff refunds. An accrual for a loss contingency or loss recovery is recognized when it is probable and the amount of loss or recovery can be reasonably estimated.
Research and Development Costs	Research and Development Costs The Company expenses research and development costs as incurred. Research and development expense consists primarily of product development personnel costs, including salaries and benefits, stock-based compensation, other professional costs and allocated facilities costs.
Stock-Based Compensation	Stock-Based Compensation Share-based payments are required to be recognized in the Company’s consolidated statements of operations based on their fair values and the estimated number of shares expected to vest. The Company measures stock-based compensation expense for all share-based payment awards, including stock options made to employees and directors, based on the estimated fair values on the date of the grant. The fair value of stock options granted is estimated using the Black-Scholes option valuation model. The fair value of restricted stock units granted is determined based on the price of the Company’s common stock on the date of grant. The fair value of non-market‑based performance stock units granted is determined based on the date of grant or when achievement of performance is probable. The fair value of market‑based performance stock units granted is determined using a Monte‑Carlo model based on the date of grant or when achievement of performance is probable. Stock-based compensation for stock options and restricted stock units (“RSUs”) is recognized on a straight-line basis over the requisite service period. Stock-based compensation for performance stock units (“PSUs”) without market conditions is recognized when the performance condition is probable of being achieved, and then on a graded basis over the requisite service period. Stock-based compensation for PSUs with market conditions is recognized on a straight-line basis over the requisite service period. Additionally, the Company estimates its forfeiture rate annually based on historical experience and revise the estimates of forfeiture in subsequent periods if actual forfeitures differ from those estimates.
Leases	Leases The Company determines if an arrangement is or contains a lease at inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments over the lease term. Operating lease assets and liabilities are recognized based on the present value of the remaining lease payments discounted using the Company’s incremental borrowing rate. Operating lease assets also include initial direct costs incurred and prepaid lease payments, minus any lease incentives. The Company’s lease terms include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense is recognized on a straight-line basis over the lease term. The Company combines the lease and non-lease components in determining the operating lease assets and liabilities.
Foreign Currency Translation	Foreign Currency Translation The Company and most of its subsidiaries use their respective local currency as their functional currency. Accordingly, foreign currency assets and liabilities are translated using exchange rates in effect at the end of the period. Aggregate exchange gains and losses arising from the translation of foreign assets and liabilities are included in accumulated other comprehensive income (loss) in stockholders' equity. Foreign subsidiaries that use the U.S. dollar as their functional currency remeasure monetary assets and liabilities using exchange rates in effect at the end of the period. In addition, transactions that are denominated in non-functional currency are remeasured using exchange rates in effect at the end of the period. Exchange gains and losses arising from the remeasurement of monetary assets and liabilities are included in other income (expense), net in the consolidated statements of operations. Non-monetary assets and liabilities are carried at their historical values.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) consists of two components, net income (loss) and other comprehensive income (loss). Other comprehensive income (loss) refers to gains and losses that are recorded as an element of stockholders’ equity but are excluded from net income (loss). The Company’s other comprehensive income (loss) consists of foreign currency translation adjustments for all periods presented.
Income Taxes	Income Taxes The Company records income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected tax consequences of temporary differences between the tax bases of assets and liabilities for financial reporting purposes and amounts recognized for income tax purposes. In estimating future tax consequences, generally all expected future events other than enactments or changes in the tax law or rates are considered. Valuation allowances are provided when necessary to reduce deferred tax assets to the amount expected to be realized. The Company assesses the realizability of the deferred tax assets to determine release of valuation allowance as necessary. In the event the Company determines that it is more likely than not that we would be able to realize deferred tax assets in the future in excess of our net recorded amount, an adjustment to the valuation allowance for the deferred tax asset would increase income in the period such determination was made. Likewise, should it be determined that additional amounts of the net deferred tax asset will not be realized in the future, an adjustment to increase the deferred tax asset valuation allowance will be charged to income in the period such determination is made. The Company operates in various tax jurisdictions and is subject to audit by various tax authorities. The Company follows accounting for uncertainty in income taxes which requires that the tax effects of a position be recognized only if it is “more likely than not” to be sustained based solely on its technical merits as of the reporting date. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.
Recently Issued Accounting Pronouncements Not Yet Effective and Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In August 2018, the FASB issued ASU 2018-15, “Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract,” to reduce diversity in practice in accounting for the costs of implementing cloud computing arrangements that are service contracts. ASU 2018-15 allows entities to apply the guidance in the ASC 350-40, “Intangibles–Goodwill and Other–Internal-Use Software,” to determine which implementation costs are eligible to be capitalized as assets in a cloud computing arrangement that is considered a service contract. ASU 2018-15 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period. Entities have the option to apply the guidance prospectively to all implementation costs incurred after the date of adoption or retrospectively and are required to make certain disclosures in the interim and annual period of adoption. The Company adopted the new standard effective January 1, 2020 on a prospective basis and the adoption of this guidance did not have a material impact on its consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with a current expected credit loss (CECL) model which will result in earlier recognition of credit losses. On January 1, 2020, the Company on a prospective basis adopted Topic 326, the measurement of expected credit losses under the CECL model is applicable to financial assets measured at amortized cost, including accounts receivable. The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements. Recently Issued Accounting Pronouncements Not Yet Effective In August 2020, the FASB issued Account Standard Update (“ASU”) 2020-06, “Debt - Debt with Conversion and Other Options (subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (subtopic 815-40),” which reduces the number of accounting models in ASC 470-20 that require separate accounting for embedded conversion features. As a result, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost as long as no other features require bifurcation and recognition as derivatives. By removing those separation models, the effective interest rate of convertible debt instruments will be closer to the coupon interest rate. Further, the diluted net income per share calculation for convertible instruments will require the Company to use the if-converted method. The treasury stock method should no longer be used to calculate diluted net income per share for convertible instruments. The amendment will be effective for the Company with annual periods beginning January 1, 2022 and early adoption is permitted. The Company is evaluating the accounting, transition and disclosure requirements of the standard
Fair Value Measurement	The accounting guidance defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities recorded at fair value, the Company considers the principal or most advantageous market in which it would transact and considers assumptions that market participants would use when pricing the asset or liability, such as inherent risk, transfer restrictions, and risk of nonperformance. The fair value hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. An asset’s or liability’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Three levels of inputs may be used to measure fair value: •Level 1 - Valuations based on quoted prices in active markets for identical assets or liabilities that the Company is able to access. Since valuations are based on quoted prices that are readily and regularly available in an active market, valuation of such assets or liabilities do not entail a significant degree of judgment. •Level 2 - Valuations based on one or more quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly. •Level 3 - Valuations based on inputs that are unobservable and significant to the overall fair value measurement.
Earnings Per Share	Basic net income (loss) per share is computed by dividing net income (loss) by the weighted average number of shares of common stock outstanding during the period. Diluted net income (loss) per share is computed in a similar manner, but it also includes the effect of potential common shares outstanding during the period, when dilutive. Potential common shares include Stock Options, RSUs, PSUs, shares to be purchased under the Company’s ESPP, the Notes due 2023, the Notes due 2024, Warrants issued in conjunction with the Notes due 2024, and from May 20, 2020 to the end of the reporting period, the Notes due 2025 and Warrants issued in conjunction with the Notes due 2025. See Note 11. “Debt” for additional information. The dilutive effect of potentially dilutive common shares is reflected in diluted earnings per share by application of the treasury stock method for stock options, RSUs, PSUs, Notes due 2024, warrants issued in conjunction with the Notes due 2024, Notes due 2025, warrants issued in conjunction with the Notes due 2025 and shares to be purchased under the ESPP, and by application of the if-converted method for the Notes due 2023. To the extent these potential common shares are antidilutive, they are excluded from the calculation of diluted net income (loss) per share.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Activity in Allowance for Doubtful Accounts

The following table sets forth activities in the allowance for doubtful accounts for the periods indicated.


	December 31,
	2020		2019		2018
	(In thousands)
Balance, at beginning of year	$	564	$	2,138	$	2,378
Net charges to expenses	425		217		711
Write-offs, net of recoveries	(527)		(1,791)		(951)
Balance, at end of year	$	462	$	564	$	2,138

REVENUE RECOGNITION (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Summary of Revenue Disaggregation

Disaggregated revenue by primary geographical market and timing of revenue recognition for the Company’s single product line are as follows:


	Years Ended December 31,
		2020		2019
		(In thousands)
Primary geographical markets:
U.S.		$	637,879	$	523,577




International		136,546		100,756
Total		$	774,425	$	624,333

Timing of revenue recognition:
Products delivered at a point in time		$	728,254	$	584,556
Products and services delivered over time		46,171		39,777
Total		$	774,425	$	624,333

Summary of Contract Assets and Contract Liabilities, and Changes in Balances from Contracts with Customers

Receivables, and contract assets and contract liabilities from contracts with customers are as follows:


	December 31, 2020		December 31, 2019
	(In thousands)
Receivables	$	182,165	$	145,413

Short-term contract assets (Prepaid expenses and other assets)	17,879		15,055
Long-term contract assets (Other assets)	51,986		42,087



Short-term contract liabilities (Deferred revenues)	47,665		81,783
Long-term contract liabilities (Deferred revenues)	125,473		100,204

Significant changes in the balances of contract assets (prepaid expenses and other assets) during the period are as follows (in thousands):


Contract Assets
Balance on December 31, 2019	$	57,142
Amount recognized	(17,652)
Increase	30,375
Balance as of December 31, 2020	$	69,865

Significant changes in the balances of contract liabilities (deferred revenues) during the period are as follows (in thousands):


Contract Liabilities
Balance on December 31, 2019	$	181,987
Revenue recognized	(87,555)

Increase due to billings	78,706

Balance as of December 31, 2020	$	173,138

Summary of Estimated Revenue Expected to be Recognized in Future Periods

Estimated revenue expected to be recognized in future periods related to performance obligations that are unsatisfied or partially unsatisfied at the end of the reporting period are as follows:


	December 31, 2020
	(In thousands)
Fiscal year:
2021	$	47,665
2022	38,402
2023	32,569
2024	27,311
2025	20,291
Thereafter	6,900
Total	$	173,138

INVENTORY (Tables)

12 Months Ended

Dec. 31, 2020

Inventory Disclosure [Abstract]

Summary of Inventory

Inventory consist of the following:



	December 31, 2020		December 31, 2019
	(In thousands)
Raw materials	$	10,140	$	4,197
Finished goods	31,624		27,859
Total inventory	$	41,764	$	32,056

PROPERTY AND EQUIPMENT, NET (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment

Property and equipment consist of the following:


	Estimated Useful Life	December 31,
		2020		2019
	(Years)	(In thousands)
Equipment and machinery	3-10	$	63,411	$	48,114
Furniture and fixtures	5-10	2,532		2,404
Computer equipment	3-5	2,972		1,698
Capitalized software costs	3-5	17,004		11,656
Leasehold improvements	3-10	9,021		8,713
Construction in process		9,747		8,446
Total		104,687		81,031
Less accumulated depreciation and amortization		(61,702)		(52,095)
Property and equipment, net		$	42,985	$	28,936

GOODWILL AND INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill and Intangible Assets

The Company’s goodwill and purchased intangible assets as of December 31, 2020 and December 31, 2019 are as follows:


	December 31, 2020								December 31, 2019
	Gross		Additions		Accumulated Amortization		Net		Gross		Accumulated Amortization		Net
	(In thousands)
Goodwill	$	24,783	$	—	$	—	$	24,783	$	24,783	$	—	$	24,783

Intangible assets:
Other indefinite-lived intangibles	286		—		—		286		286		—		286

Intangible assets with finite lives:

Developed technology	13,100		—		(5,276)		7,824		13,100		(3,093)		10,007
Customer relationships	23,100		3,321		(5,723)		20,698		23,100		(2,814)		20,286
Total purchased intangible assets	$	36,486	$	3,321	$	(10,999)	$	28,808	$	36,486	$	(5,907)	$	30,579

Schedule of Amortization Expense

Amortization expense related to finite-lived intangible assets are as follows:


	Years Ended December 31,
		2020		2019
		(In thousands)
Developed technology, and patents and licensed technology		$	2,183	$	2,184
Customer relationships		2,909		2,543
Total amortization expense		$	5,092	$	4,727

ACCRUED LIABILITIES (Tables)

12 Months Ended

Dec. 31, 2020

Payables and Accruals [Abstract]

Schedule of Accrued Liabilities

Accrued liabilities consist of the following:


	December 31, 2020		December 31, 2019
	(In thousands)
Salaries, commissions, incentive compensation and benefits	$	6,634	$	5,524
Customer rebates and sales incentives	36,622		24,198
Freight	10,300		4,908
Operating lease liabilities, current	4,542		3,170
Liability due to supply agreements	5,500		1,729
Other	12,944		7,563
Total accrued liabilities	$	76,542	$	47,092

WARRANTY OBLIGATIONS (Tables)

12 Months Ended

Dec. 31, 2020

Product Warranties Disclosures [Abstract]

Summary of Warranty Activities

The Company’s warranty activities were as follows:


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Warranty obligations, beginning of period		$	37,098	$	31,294	$	29,816
Accruals for warranties issued during period		7,021		5,244		3,040
Changes in estimates		9,954		8,591		6,515
Settlements		(12,811)		(10,881)		(8,579)
Increase due to accretion expense		3,255		2,326		1,989
Other		1,396		524		(1,487)
Warranty obligations, end of period		45,913		37,098		31,294
Less: current portion		(11,260)		(10,078)		(8,083)
Noncurrent		$	34,653	$	27,020	$	23,211

FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of Liabilities Measured at Fair Value on a Recurring Basis

The following table presents the Company’s warranty obligations that were measured at fair value on a recurring basis and its categorization within the fair value hierarchy.


	December 31, 2020		December 31, 2019
	(In thousands)
	Level 3		Level 3







Liabilities:







Warranty obligations
Current	$	8,267	$	6,794
Non-current	20,469		13,012
Total warranty obligations measured at fair value	28,736		19,806
Total liabilities measured at fair value	$	28,736	$	19,806

The following table presents the fair value and the change in fair value for the Convertible notes hedge asset and Warrants liability:


	Convertible notes hedge		Warrants liability
	(In thousands)
Fair value as of March 9, 2020	$	89,056	$	71,552



Change in the fair value	28,052		24,799
Fair value as of May 20, 2020	$	117,108	$	96,351

Schedule of Changes in Nonfinancial Liabilities Related to Warrant Obligations Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Balance at beginning of period		$	19,806	$	11,757	$	9,791
Accruals for warranties issued during period		7,021		5,244		3,040
Changes in estimates		5,039		6,167		2,455
Settlements		(7,781)		(6,212)		(4,030)
Increase due to accretion expense		3,255		2,326		1,989
Other		1,396		524		(1,488)
Balance at end of period		$	28,736	$	19,806	$	11,757

Summary of Significant Unobservable Inputs used in the Fair Value Measurement of Liabilities Designated as Level 3

As of December 31, 2020 and December 31, 2019, the significant unobservable inputs used in the fair value measurement of the Company’s liabilities designated as Level 3 are as follows:

Percent Used

(Weighted Average)

Item Measured at Fair Value

Valuation Technique

Description of Significant Unobservable Input

December 31,
2020

December 31,
2019

Warranty obligations for microinverters sold since January 1, 2014

Discounted cash flows

Profit element and risk premium

15%

14%

Credit-adjusted risk-free rate

13%

16%

RESTRUCTURING (Tables)

12 Months Ended

Dec. 31, 2020

Restructuring and Related Activities [Abstract]

Restructuring and Related Costs

Restructuring expense consist of the following:


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Redundancy and employee severance and benefit arrangements		$	—	$	1,575	$	2,228
Asset impairments		—		1,124		1,601
Consultants engaged in restructuring activities		—		—		—
Lease loss reserves (benefit)		—		(100)		300

Total restructuring charges		$	—	$	2,599	$	4,129

The following table presents the details of the Company’s restructuring charges under the 2018 Plan for the period indicated:


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Redundancy and employee severance and benefit arrangements		$	—	$	1,575	$	2,228
Asset impairments		—		1,124		1,636

Lease loss reserves (benefit)		—		(100)		340

Total restructuring charges		$	—	$	2,599	$	4,204

Schedule of Restructuring Reserve by Type of Cost

The following table provides information regarding changes in the Company’s 2018 Plan accrued restructuring balance for the periods indicated.


	Redundancy and Employee Severance and Benefits		Lease Loss Reserves and Contractual Obligations		Total
	(In thousands)




Balance as of December 31, 2018	$	904	$	288	$	1,192
Charges	2,699		—		2,699
Cash payments	(1,610)		—		(1,610)
Non-cash settlement and other	(1,993)		(288)		(2,281)
Balance as of December 31, 2019	$	—	$	—	$	—

The following table provides information regarding changes in the Company’s 2016 Plan accrued restructuring balance for the periods indicated.


	Employee Severance and Benefits		Asset Impairments		Lease Loss Reserves and Contractual Obligations		Total
	(In thousands)








Balance as of December 31, 2018	—		—		$	1,591	1,591


Other (1)	—		—		(1,591)		(1,591)
Balance as of December 31, 2019	$	—	$	—	$	—	$	—

(1) Adoption of ASU 2016-02 -Leases.

DEBT (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Schedule of Debt

The following table provides information regarding the Company’s long-term debt.


	December 31, 2020		December 31, 2019
	(In thousands)
Convertible notes
Notes due 2025	$	320,000	$	—
Less: unamortized discount and issuance costs	(64,979)		—
Carrying amount of Notes due 2025	255,021		—



Notes due 2024	88,140		132,000
Less: unamortized discount and issuance costs	(19,119)		(35,815)
Carrying amount of Notes due 2024	69,021		96,185

Notes due 2023	5,000		5,000
Less: unamortized issuance costs	(102)		(143)
Carrying amount of Notes due 2023	4,898		4,857









Sale of long-term financing receivable recorded as debt	1,925		4,501


Total carrying amount of debt	330,865		105,543

Less: current portion of convertible notes and long-term financing receivable recorded as debt	(325,967)		(2,884)
Long-term debt	$	4,898	$	102,659

The following table presents the total amount of interest cost recognized relating to the Notes due 2025 (in thousands):


	Year Ended December 31, 2020



Contractual interest expense	$	649
Amortization of debt discount	10,072
Amortization of debt issuance costs	1,229
Total interest cost recognized	$	11,950

The following table presents the total amount of interest cost recognized in the statement of operations relating to the Notes due 2024:


	Years Ended December 31,
		2020		2019
		(In thousands)
Contractual interest expense		$	1,284	$	759
Amortization of debt discount		6,325		3,492
Amortization of debt issuance costs		646		375
Total interest cost recognized		$	8,255	$	4,626

The following table presents the amount of interest cost recognized relating to the contractual interest coupon and the amortization of debt issuance costs of the Notes due 2023.



	Years Ended December 31,
		2020		2019
		(In thousands)
Contractual interest expense		$	200	$	1,226

Amortization of debt issuance costs		40		245
Total interest costs recognized		$	240	$	1,471

Schedule of Derivative Instruments

The following table presents the fair value and the change in fair value for the convertible note embedded derivative (in thousands):


Convertible note embedded derivative liability

Fair value as of March 9, 2020	$	68,700



Change in the fair value	47,600
Fair value as of May 20, 2020	$	116,300

Schedule of Fair Value Of Convertible Notes Hedge and Warrants Liability

The following table presents the Company’s warranty obligations that were measured at fair value on a recurring basis and its categorization within the fair value hierarchy.


	December 31, 2020		December 31, 2019
	(In thousands)
	Level 3		Level 3







Liabilities:







Warranty obligations
Current	$	8,267	$	6,794
Non-current	20,469		13,012
Total warranty obligations measured at fair value	28,736		19,806
Total liabilities measured at fair value	$	28,736	$	19,806

The following table presents the fair value and the change in fair value for the Convertible notes hedge asset and Warrants liability:


	Convertible notes hedge		Warrants liability
	(In thousands)
Fair value as of March 9, 2020	$	89,056	$	71,552



Change in the fair value	28,052		24,799
Fair value as of May 20, 2020	$	117,108	$	96,351

- Definition

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121590274&loc=d3e41620-113959

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121590274&loc=d3e41638-113959

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=121590274&loc=d3e41678-113959

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121590274&loc=d3e41641-113959

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579240-113959

+ Details

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Components of Lease

The components of lease expense are presented as follows:


	Years Ended December 31,
		2020		2019
		(In thousands)
Operating lease costs		$	5,332	$	4,041

The components of lease liabilities are presented as follows:


	December 31, 2020		December 31, 2019
	(In thousands)
Operating lease liabilities, current (Accrued liabilities)	$	4,542	$	3,170
Operating lease liabilities, noncurrent (Other liabilities)	15,209		9,542
Total operating lease liabilities	$	19,751	$	12,712

Supplemental lease information:
Weighted average remaining lease term	6.4 years		5.5 years
Weighted average discount rate	7.7%		8.6%

Supplemental cash flow and other information related to operating leases, are as follows:


	Years Ended December 31,
		2020		2019
		(In thousands)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases		$	4,762	$	3,636

Non-cash investing activities:
Lease liabilities arising from obtaining right-of-use assets		$	10,625	$	4,834

Schedule of Future Minimum Rental Payments for Operating Leases

Undiscounted cash flows of operating lease liabilities as of December 31, 2020 are as follows:


	Lease Amounts
	(In thousands)
Year:
2021	$	5,830
2022	4,677
2023	4,056
2024	3,069
2025	2,275
2026 and thereafter	3,968
Total lease payments	23,875
Less: imputed lease interest	(4,124)
Total lease liabilities	$	19,751

STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Summary of the Components of Total Stock-Based Compensation Expense

The following table summarizes the components of total stock-based compensation expense included in the consolidated statements of operations for the periods presented.


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Cost of revenues		$	3,759	$	1,650	$	1,071
Research and development		12,701		4,897		2,940
Sales and marketing		11,548		5,678		3,074
General and administrative		14,495		7,216		4,347
Restructuring		—		735		—
Total		$	42,503	$	20,176	$	11,432
Income tax benefit included in the provision for incomes taxes		$	61,389	$	8,185	$	—

Summary of Stock-Based Compensation Associated with Each Type of Award

The following table summarizes the various types of stock-based compensation expense for the periods presented.


	Years Ended December 31,
		2020		2019		2018
		(In thousands)
Stock options, RSUs, and PSUs		$	39,841	$	19,216	$	10,691
Employee stock purchase plan		2,662		960		741

Total		$	42,503	$	20,176	$	11,432

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions


	Years Ended December 31,
		2020		2019		2018
Weighted average grant date fair value		$	38.45	$	9.16	$	2.83
Expected term (in years)		3.8		3.8		4.0
Expected volatility		86.4%		89.1%		88.5%
Annual risk-free rate of return		0.1%		2.1%		2.6%
Dividend yield		—%		—%		—%

Share-based Compensation, Performance Shares Award Outstanding Activity

The following is a summary of PSU activity.


	Number of Shares Outstanding	Weighted- Average Fair Value per Share at Grant Date		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value (1)
	(In thousands)			(Years)	(In thousands)
Outstanding at December 31, 2017	—
Granted	1,477	$	4.65
Vested	—
Canceled	(147)
Outstanding at December 31, 2018	1,330	$	4.66
Granted	1,052	9.48
Vested	(1,063)	4.62			10,818
Canceled	(364)	5.16
Outstanding at December 31, 2019	955	$	9.83
Granted	989	31.12
Vested	(1,450)	10.20			$	52,144
Canceled	—	—
Outstanding at December 31, 2020	494	$	51.10	0.2	$	86,668

Summary of Stock Option Activity

The following is a summary of stock option activity.


	Number of Shares Outstanding	Weighted- Average Exercise Price per Share		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value (1)
	(In thousands)			(Years)	(In thousands)
Outstanding at December 31, 2017	8,426	$	1.77
Granted	213	4.43
Exercised	(1,346)	1.75			$	5,096
Canceled	(521)	2.94
Outstanding at December 31, 2018	6,772	$	1.76
Granted	43	14.58
Exercised	(2,616)	1.22			$	31,093
Canceled	(102)	4.07
Outstanding at December 31, 2019	4,097	$	2.18
Granted	11	64.17
Exercised	(1,494)	2.74			$	114,089
Canceled	(82)	6.94
Outstanding at December 31, 2020	2,532	$	1.96	3.7	$	439,268
Vested and expected to vest at December 31, 2020	2,532	$	1.96	3.7	$	439,268
Exercisable at December 31, 2020	2,089	$	1.95	3.7	$	362,526

Summary of Stock Option Outstanding

The following table summarizes information about stock options outstanding at December 31, 2020.


	Options Outstanding				Options Exercisable
Range of Exercise Prices	Number of Shares	Weighted- Average Remaining Life	Weighted- Average Exercise Price		Number of Shares	Weighted- Average Exercise Price
	(In thousands)	(Years)			(In thousands)
$0.70 —– $1.11	555	4.2	$	0.85	448	$	0.83
$1.29 —– $1.29	1,000	3.7	1.29		813	1.29
$1.31 —– $1.31	670	3.3	1.31		587	1.31
$1.37 —– $14.58	296	3.6	5.56		235	6.37
$64.17 —– $64.17	11	6.3	64.17		6	64.17
Total	2,532	3.7	$	1.96	2,089	$	1.95

Summary of Restricted Stock Unit Activity

The following is a summary of RSU activity.


	Number of Shares Outstanding	Weighted- Average Fair Value per Share at Grant Date		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value (1)
	(In thousands)			(Years)	(In thousands)
Outstanding at December 31, 2017	3,505	$	2.03
Granted	3,152	4.45
Vested	(1,399)	2.75			$	6,657
Canceled	(906)	2.17
Outstanding at December 31, 2018	4,352	$	3.52
Granted	2,112	11.50
Vested	(1,707)	3.87			$	27,156
Canceled	(494)	4.81
Outstanding at December 31, 2019	4,263	$	7.19
Granted	1,550	55.66
Vested	(2,085)	7.26			$	125,578
Canceled	(140)	19.47
Outstanding at December 31, 2020	3,588	$	27.61	1.08	$	629,633
Expected to vest at December 31, 2020	3,588	$	27.61	1.08	$	629,633

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity

A summary of ESPP activity for the years presented is as follows: (in thousands, except per share data):


	Years Ended December 31,
	2020		2019		2018
Proceeds from common stock issued under ESPP	$	4,304	$	1,692	$	397
Shares of common stock issued	347		315		439
Weighted-average price per share	$	12.41	$	5.37	$	0.90

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Domestic and Foreign Components of Loss before Provision for Income Taxes

The domestic and foreign components of income (loss) before income taxes consisted of the following:


	Years Ended December 31,
	2020		2019		2018
	(In thousands)
United States	$	112,727	$	85,520	$	(14,322)
Foreign	6,683		4,594		4,093
Income (loss) before income taxes	$	119,410	$	90,114	$	(10,229)

Schedule of Provision for Income Taxes

The income taxes (benefit) provision for the years presented is as follows:


	Years Ended December 31,
	2020		2019		2018
	(In thousands)
Current:
Federal	$	—	$	—	$	—
State	636		327		42
Foreign	1,896		1,589		1,233
	2,532		1,916		1,275
Deferred:
Federal	(13,445)		(56,959)		(35)
State	(3,672)		(17,458)		(21)
Foreign	—		1,467		179
	(17,117)		(72,950)		123
Income taxes (benefit) provision	$	(14,585)	$	(71,034)	$	1,398

Schedule of Effective Income Tax Rate Reconciliation


	Years Ended December 31,
	2020		2019		2018
	(In thousands)
Income tax (benefit) provision at statutory federal rate	$	25,076	$	18,929	$	(2,148)
State taxes, net of federal benefit	(3,098)		(17,197)		17
Change in valuation allowance	—		(71,300)		8,198
Foreign tax rate and tax law differential	611		1,206		313
Tax credits	(5,835)		(1,803)		(378)
Stock-based compensation	(50,818)		(8,072)		(953)
Other permanent items	(253)		31		235

Other nondeductible/nontaxable items	1,525		2,765		(5,112)
Uncertain tax positions	1,530		504		107

GILTI	—		1,086		917
Section 162(m)	11,469		2,817		202
Warrant mark-to-mark adjustment	5,208		—		—
Income tax (benefit) provision	$	(14,585)	$	(71,034)	$	1,398

Schedule of Deferred Tax Assets and Liabilities

A summary of significant components of the Company’s deferred tax assets and liabilities as of December 31, 2020 and 2019 is as follows (in thousands):


	December 31,
	2020		2019
Deferred tax assets:
Allowances and reserves	$	13,146	$	10,726
Net operating loss and tax credit carryforwards	53,116		54,369
Stock-based compensation	4,598		3,753
Deferred revenue	20,765		16,736
Fixed assets and intangibles	8,706		2,720
Sec. 163(j) interest carryforward	4,401		—
Other	7,007		1,109
Subtotal	111,739		89,413

Total deferred tax assets	111,739		89,413
Deferred tax liabilities:
Goodwill	(1,719)		(1,368)
Unremitted foreign earnings	(7)		(5)
Deferred cost of goods sold	(17,545)		(14,374)
Total deferred tax liabilities	(19,271)		(15,747)
Net deferred tax asset	$	92,468	$	73,666

Schedule of Reconciliation of Total Amounts of Unrecognized Tax Benefits

A tabular reconciliation of the total amounts of unrecognized tax benefits for the years presented is as follows (in thousands):


	Years Ended December 31,
	2020		2019		2018
Unrecognized tax benefits—at beginning of year	$	6,589	$	6,325	$	6,106

Decreases in balances related to tax positions taken in prior years	—		(370)		—
Increases in balances related to tax positions taken in current year	2,006		771		329

Lapses in statutes of limitations	(174)		(137)		(110)
Unrecognized tax benefits—at end of year	$	8,421	$	6,589	$	6,325

NET INCOME PER SHARE (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Net Income Per Share

The following table presents the computation of basic and diluted net income (loss) per share for the periods presented.


	Years Ended December 31,
		2020		2019		2018
		(In thousands, except per share data)
Numerator:
Net income (loss)		$	133,995	$	161,148	$	(11,627)
Notes due 2023 interest and financing costs, net		177		1,088		—
Adjusted net income (loss)		$	134,172	$	162,236	$	(11,627)

Denominator:
Shares used in basic per share amounts:
Weighted average common shares outstanding		125,561		116,713		99,619

Shares used in diluted per share amounts:
Weighted average common shares outstanding		125,561		116,713		99,619
Effect of dilutive securities:
Employee stock-based awards		6,997		8,964		—

Warrants (issued in conjunction with Notes due 2024)		4,011		—		—

Notes due 2024		4,449		451		—
Notes due 2023		900		5,516		—
Weighted average common shares outstanding for diluted calculation		141,918		131,644		99,619

Basic and diluted net income (loss) per share
Net income (loss) per share, basic		$	1.07	$	1.38	$	(0.12)
Net income (loss) per share, diluted		$	0.95	$	1.23	$	(0.12)

Schedule of Potentially Dilutive Securities Excluded from the Computation of Diluted Net Income Per Share


	Years Ended December 31,
		2020	2019	2018
		(In thousands)
Employee stock options		7	27	7,710
RSUs and PSUs		36	158	5,273



Warrants (issued in conjunction with Notes due 2024)		—	300	—


Warrants (issued in conjunction with Notes due 2025)		1,254	—	—
Notes due 2025		197	—
Notes due 2023		—	—	11,701
Total		1,494	485	24,684

SEGMENT AND GEOGRAPHIC INFORMATION (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Summary of Net Revenues and Long-Lived Assets by Geographic Region

The following table presents long-lived assets by geographic region as of and for the periods presented (in thousands):

Long-Lived Assets


	December 31,
	2020		2019
	(In thousands)
United States	$	19,870	$	16,754
China	9,948		4,635
Mexico	4,808		3,510
India	4,371		1,315
New Zealand	3,837		2,638
Other	151		84
Total	$	42,985	$	28,936

ACQUISITION (Tables)

12 Months Ended

Dec. 31, 2020

Business Combinations [Abstract]

Summary of consideration transferred for business acquisition

The acquisition date fair value of the consideration transferred was approximately $57.3 million, which consisted of the following (in thousands):


Cash consideration	$	25,000
Common stock issued	32,319
Total	$	57,319

Summary of fair values of assets acquired and liabilities assumed

The following table summarizes the preliminary estimated fair values of the assets acquired and liabilities assumed at the acquisition date (in thousands):



Intangible assets	$	36,200
Goodwill	21,119
Net assets acquired	$	57,319

The table below shows estimated fair values of the assets acquired funded by cash and issuance of common stock at the acquisition date:


	Cash Purchase Price		Issuance of Common Stock		Total Consideration		% of Total Consideration
	(In thousands)
Developed technology and goodwill	$	15,000	$	19,219	$	34,219	60	%
Customer relationship	10,000		13,100		23,100		40	%
Total consideration	$	25,000	$	32,319	$	57,319	100	%

Summary of identifiable intangible assets acquired

The following table shows the fair value of the separately identifiable intangible assets at the time of acquisition and the period over which each intangible asset will be amortized:


	Preliminary Fair Value		Useful Life
	(In thousands)		(Years)
Developed technology	$	13,100	6
Customer relationship	23,100		9
Total identifiable intangible assets	$	36,200

SELECTED UNAUDITED QUARTERLY FINANCIAL INFORMATION (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

SELECTED UNAUDITED QUARTERLY FINANCIAL INFORMATION

The following tables show a summary of the Company’s quarterly financial information for each of the four quarters of 2020 and 2019 (in thousands, except per share data):


	Three Months Ended
	March 31, 2020		June 30, 2020		September 30, 2020		December 31, 2020
Net revenues	$	205,545	$	125,538	$	178,503	$	264,839
Cost of revenues	124,870		77,151		83,522		142,901
Gross profit	80,675		48,387		94,981		121,938
Operating expenses:
Research and development	11,876		13,192		15,052		15,801
Sales and marketing	11,772		12,371		14,645		14,139
General and administrative	12,315		11,970		13,525		12,884

Total operating expenses	35,963		37,533		43,222		42,824
Income from operations	44,712		10,854		51,759		79,114
Other income (expense), net
Interest Income	1,091		282		110		673
Interest expense	(3,155)		(5,952)		(5,993)		(5,901)
Other income (expense)	(924)		653		(1,031)		(2,534)
Change in fair value of derivatives	15,344		(59,692)		—		—
Total other income (expense), net	12,356		(64,709)		(6,914)		(7,762)



Income (loss) before income taxes	57,068		(53,855)		44,845		71,352
Income tax benefit (provision)	11,868		6,561		(5,483)		1,639
Net income (loss)	$	68,936	$	(47,294)	$	39,362	$	72,991
Net income (loss) per share, basic	$	0.56	$	(0.38)	$	0.31	$	0.57
Net income (loss) per share, diluted	$	0.50	$	(0.38)	$	0.28	$	0.50


	Three Months Ended
	March 31, 2019		June 30, 2019		September 30, 2019		December 31, 2019
Net revenues	$	100,150	$	134,094	$	180,057	$	210,032
Cost of revenues	66,811		88,775		115,351		132,151
Gross profit	33,339		45,319		64,706		77,881
Operating expenses:
Research and development	8,524		9,604		11,085		11,168
Sales and marketing	7,433		9,054		9,551		10,690
General and administrative	9,880		8,583		9,895		10,450
Restructuring charges	368		631		469		1,131
Total operating expenses	26,205		27,872		31,000		33,439
Income from operations	7,134		17,447		33,706		44,442
Other expense, net
Interest income	211		593		894		815
Interest expense	(3,751)		(1,351)		(2,286)		(2,303)
Other income (expense), net	(481)		(5,480)		(943)		1,467
Total other expense, net	(4,021)		(6,238)		(2,335)		(21)


Income before income taxes	3,113		11,209		31,371		44,421
Income tax benefit (provision)	(348)		(591)		(272)		72,245
Net income	$	2,765	$	10,618	$	31,099	$	116,666
Net income per share, basic	$	0.03	$	0.09	$	0.25	$	0.95
Net income per diluted share	$	0.02	$	0.08	$	0.23	$	0.88

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Mar. 09, 2020
Fair Value, Option, Quantitative Disclosures [Line Items]
Restricted cash	$ 0	$ 44,700,000	$ 0
Asset impairment	0	1,100,000	1,600,000
Goodwill, impairment loss	0	0	0
Impairment of intangible assets	$ 0	$ 0	$ 0
Product warranty, term	25 years
Convertible Senior Notes Due 2025 \| Convertible Notes
Fair Value, Option, Quantitative Disclosures [Line Items]
Debt instrument face amount				$ 320,000,000	$ 320,000,000
Interest rate				0.25%	0.25%
Monitoring Hardware And Service
Fair Value, Option, Quantitative Disclosures [Line Items]
Capitalized contract cost, amortization period	6 years
First and Second Generation
Fair Value, Option, Quantitative Disclosures [Line Items]
Product warranty, term	15 years
Third and Fourth Generation
Fair Value, Option, Quantitative Disclosures [Line Items]
Product warranty, term	25 years
Envoy Communications Gateway
Fair Value, Option, Quantitative Disclosures [Line Items]
Product warranty, term	5 years
AC Battery Storage Solution
Fair Value, Option, Quantitative Disclosures [Line Items]
Product warranty, term	10 years
Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Property, plant and equipment, useful life	3 years
Intangible assets, estimated useful life	3 years
Period failure rate measurement lags product sale	3 months
Minimum \| Communication Accessories
Fair Value, Option, Quantitative Disclosures [Line Items]
Service period	5 years
Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Property, plant and equipment, useful life	10 years
Intangible assets, estimated useful life	9 years
Period failure rate measurement lags product sale	9 months
Maximum \| Communication Accessories
Fair Value, Option, Quantitative Disclosures [Line Items]
Service period	12 years

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Activity in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance, at beginning of year	$ 564	$ 2,138	$ 2,378
Net charges to expenses	425	217	711
Write-offs, net of recoveries	(527)	(1,791)	(951)
Balance, at end of year	$ 462	$ 564	$ 2,138

REVENUE RECOGNITION - Summary of Disaggregated Revenue by Primary Geographical Market and Timing of Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net revenues	$ 264,839	$ 178,503	$ 125,538	$ 205,545	$ 210,032	$ 180,057	$ 134,094	$ 100,150	$ 774,425	$ 624,333	$ 316,159
Products delivered at a point in time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net revenues									728,254	584,556
Products and services delivered over time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net revenues									46,171	39,777
U.S.
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net revenues									637,879	523,577
International
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net revenues									$ 136,546	$ 100,756

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

REVENUE RECOGNITION - Summary of Contract Assets and Contract Liabilities from Contracts with Customers (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Receivables	$ 182,165	$ 145,413
Short-term contract assets (Prepaid expenses and other assets)	17,879	15,055
Long-term contract assets (Other assets)	51,986	42,087
Short-term contract liabilities (Deferred revenues)	47,665	81,783
Long-term contract liabilities (Deferred revenues)	$ 125,473	$ 100,204

REVENUE RECOGNITION - Narrative (Details)	12 Months Ended
REVENUE RECOGNITION - Narrative (Details)	Dec. 31, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Contract asset impairment charges	$ 0

REVENUE RECOGNITION - Summary of Significant Changes in the Balances of Contract Liabilities and Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Contract Assets
Balance, beginning of period	$ 57,142
Revenue recognized	(17,652)
Increase	30,375
Balance, end of period	69,865
Contract Liabilities
Balance, beginning of period	181,987
Revenue recognized	(87,555)
Increase due to billings	78,706
Balance, end of period	$ 173,138

REVENUE RECOGNITION - Summary of Estimated Revenue Expected to be Recognized in Future Periods (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Revenue from Contract with Customer [Abstract]
Total estimated revenue expected to be recognized in future periods	$ 173,138
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue from Contract with Customer [Abstract]
Total estimated revenue expected to be recognized in future periods	$ 47,665
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total estimated revenue expected to be recognized in future periods, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue from Contract with Customer [Abstract]
Total estimated revenue expected to be recognized in future periods	$ 38,402
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total estimated revenue expected to be recognized in future periods, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Total estimated revenue expected to be recognized in future periods	$ 32,569
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total estimated revenue expected to be recognized in future periods, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue from Contract with Customer [Abstract]
Total estimated revenue expected to be recognized in future periods	$ 27,311
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total estimated revenue expected to be recognized in future periods, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue from Contract with Customer [Abstract]
Total estimated revenue expected to be recognized in future periods	$ 20,291
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total estimated revenue expected to be recognized in future periods, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue from Contract with Customer [Abstract]
Total estimated revenue expected to be recognized in future periods	$ 6,900
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total estimated revenue expected to be recognized in future periods, expected timing

INVENTORY - Summary of Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 10,140	$ 4,197
Finished goods	31,624	27,859
Total inventory	$ 41,764	$ 32,056

PROPERTY AND EQUIPMENT, NET - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 104,687	$ 81,031
Less accumulated depreciation and amortization	(61,702)	(52,095)
Property and equipment, net	$ 42,985	28,936
Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Equipment and machinery
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 63,411	48,114
Equipment and machinery \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Equipment and machinery \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 2,532	2,404
Furniture and fixtures \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Furniture and fixtures \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 2,972	1,698
Computer equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Computer equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Capitalized software costs
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 17,004	11,656
Capitalized software costs \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Capitalized software costs \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 9,021	8,713
Leasehold improvements \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Leasehold improvements \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Construction in process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 9,747	$ 8,446

PROPERTY AND EQUIPMENT, NET - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 9.7	$ 7.3	$ 8.3
Unamortized capitalized software costs	$ 4.8	$ 0.8

GOODWILL AND INTANGIBLE ASSETS - Schedule of Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Aug. 09, 2018
Finite-Lived Intangible Assets [Line Items]
Goodwill, Gross	$ 24,783	$ 24,783
Goodwill, Net	24,783	24,783
Intangible assets with finite lives:
Other indefinite-lived intangibles	286	286
Other indefinite-lived intangibles, Additions	0
Accumulated Amortization	(10,999)	(5,907)
Total purchased intangible assets, Gross	36,486	36,486
Total purchased intangible assets, Gross, Additions	3,321
Total purchased intangible assets, Net	28,808	30,579
Developed technology
Intangible assets with finite lives:
Gross	13,100	13,100
Additions	0
Accumulated Amortization	(5,276)	(3,093)
Net	7,824	10,007
Customer relationship
Intangible assets with finite lives:
Gross	23,100	23,100	$ 23,100
Additions	3,321
Accumulated Amortization	(5,723)	(2,814)
Net	$ 20,698	$ 20,286

GOODWILL AND INTANGIBLE ASSETS - Amortization Expense (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Aug. 09, 2018	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets			$ 5,092	$ 4,727
Developed technology, and patents and licensed technology
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets			2,183	2,184
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets			2,909	2,543
Intangible assets	$ 23,100	$ 23,100	23,100	$ 23,100
Additions			$ 3,321
SunPower’s
Finite-Lived Intangible Assets [Line Items]
Amortization period for acquired intangible assets	15 years
Agreement for exclusive supplier rights, period	5 years	3 months
SunPower’s \| Developed technology, and patents and licensed technology
Finite-Lived Intangible Assets [Line Items]
Amortization period for acquired intangible assets	6 years
SunPower’s \| Customer relationships
Finite-Lived Intangible Assets [Line Items]
Amortization period for acquired intangible assets	9 years

ACCRUED LIABILITIES - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued Liabilities [Abstract]
Salaries, commissions, incentive compensation and benefits	$ 6,634	$ 5,524
Customer rebates and sales incentives	36,622	24,198
Freight	10,300	4,908
Operating lease liabilities, current	4,542	3,170
Liability due to supply agreements	5,500	1,729
Other	12,944	7,563
Total accrued liabilities	$ 76,542	$ 47,092

WARRANTY OBLIGATIONS - Summary of Warranty Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in the Company's product warranty liability
Warranty obligations, beginning of period	$ 37,098	$ 31,294	$ 29,816
Accruals for warranties issued during period	7,021	5,244	3,040
Changes in estimates	9,954	8,591	6,515
Settlements	(12,811)	(10,881)	(8,579)
Increase due to accretion expense	3,255	2,326	1,989
Other	1,396	524	(1,487)
Warranty obligations, end of period	45,913	37,098	31,294
Less: current portion	(11,260)	(10,078)	(8,083)
Noncurrent	$ 34,653	$ 27,020	$ 23,211

WARRANTY OBLIGATIONS - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Product Warranty Liability [Line Items]
Additional warranty expense	$ 9,954	$ 8,591	$ 6,515
Failure Rates
Product Warranty Liability [Line Items]
Additional warranty expense	8,800
Failure Rates \| Second And Third Generations
Product Warranty Liability [Line Items]
Additional warranty expense		3,100	3,300
Increased Tariffs And Labor Reimbursement Costs
Product Warranty Liability [Line Items]
Additional warranty expense	$ 1,200
Increased U.S. Tariffs For Products Manufactured In China
Product Warranty Liability [Line Items]
Additional warranty expense		$ 5,500
Backwards Compatibility Cables
Product Warranty Liability [Line Items]
Additional warranty expense			900
Claim Rates
Product Warranty Liability [Line Items]
Additional warranty expense			2,100
Labor Reimbursement Costs
Product Warranty Liability [Line Items]
Additional warranty expense			200
Discount Rate
Product Warranty Liability [Line Items]
Additional warranty expense			$ 1,500

FAIR VALUE MEASUREMENTS - Narrative (Details) - USD ($)	12 Months Ended
FAIR VALUE MEASUREMENTS - Narrative (Details) - USD ($)	Dec. 31, 2020	May 20, 2020	Mar. 31, 2020	Mar. 09, 2020	Jun. 05, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants obligations measured at fair value		$ 96,400,000
Investment without readily determinable fair value	$ 5,000,000.0
Increase in liability as a result of increasing the profit element and risk premium input by 100 basis points	200,000
Decrease in liability as a result of decreasing the profit element and risk premium input by 100 basis points	200,000
Decrease in liability as a result of increasing the discount rate by 100 basis points	1,400,000
Increase in liability as a result of decreasing the discount rate by 100 basis points	1,600,000
Convertible Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible notes embedded derivative		117,100,000
Convertible Notes \| Convertible Senior Notes Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument face amount			$ 320,000,000	$ 320,000,000
Interest rate			0.25%	0.25%
Convertible notes embedded derivative		116,300,000		$ 68,700,000
Warrants obligations measured at fair value		$ 96,351,000		$ 71,552,000
Convertible Notes \| Convertible Senior Notes Due 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument face amount	88,100,000				$ 132,000,000.0
Interest rate					1.00%
Level 1 \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	654,700,000
Level 2 \| Recurring \| Convertible Notes \| Convertible Senior Notes Due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable fair value	725,500,000
Level 2 \| Recurring \| Convertible Notes \| Convertible Senior Notes Due 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable fair value	$ 747,100,000

FAIR VALUE MEASUREMENTS - Schedule of Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liabilities:
Warranty obligations, current	$ 11,260	$ 10,078	$ 8,083
Warranty obligations, non-current	34,653	27,020	23,211
Total warranty obligations measured at fair value	45,913	37,098	$ 31,294	$ 29,816
Recurring \| Level 3
Liabilities:
Warranty obligations, current	8,267	6,794
Warranty obligations, non-current	20,469	13,012
Total warranty obligations measured at fair value	28,736	19,806
Total liabilities measured at fair value	$ 28,736	$ 19,806

FAIR VALUE MEASUREMENTS - Schedule of Changes in Nonfinancial Liabilities Related to Warrant Obligations Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - Level 3 - Recurring - Total warranty obligations measured at fair value - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 19,806	$ 11,757	$ 9,791
Accruals for warranties issued during period	7,021	5,244	3,040
Changes in estimates	5,039	6,167	2,455
Settlements	(7,781)	(6,212)	(4,030)
Increase due to accretion expense	3,255	2,326	1,989
Other	1,396	524	(1,488)
Balance at end of period	$ 28,736	$ 19,806	$ 11,757

FAIR VALUE MEASUREMENTS - Summary of Significant Unobservable Inputs used in the Fair Value Measurement of Liabilities Designated as Level 3 (Details) - Recurring - Level 3 - Warranty obligations for microinverters sold since January 1, 2014	Dec. 31, 2020	Dec. 31, 2019
Profit element and risk premium
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warranty obligations, measurement input	15.00%	14.00%
Credit-adjusted risk-free rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warranty obligations, measurement input	13.00%	16.00%

RESTRUCTURING - Summary of Restructuring Charges (Details) - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 1,131,000	$ 469,000	$ 631,000	$ 368,000	$ 0	$ 2,599,000	$ 4,129,000
Asset impairments					0	1,100,000	1,600,000
Restructuring Plan 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges					0	2,599,000	4,204,000
Redundancy and employee severance and benefit arrangements
Restructuring Cost and Reserve [Line Items]
Restructuring charges					0	1,575,000	2,228,000
Redundancy and employee severance and benefit arrangements \| Restructuring Plan 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges					0	1,575,000	2,228,000
Asset impairments
Restructuring Cost and Reserve [Line Items]
Asset impairments					0	1,124,000	1,601,000
Asset impairments \| Restructuring Plan 2018
Restructuring Cost and Reserve [Line Items]
Asset impairments					0	1,124,000	1,636,000
Consultants engaged in restructuring activities
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, accrual adjustment					0	0	0
Lease loss reserves (benefit)
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, accrual adjustment					0	(100,000)	300,000
Lease loss reserves (benefit) \| Restructuring Plan 2018
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, accrual adjustment					$ 0	$ (100,000)	$ 340,000

RESTRUCTURING - Rollforward (Details) $ in Thousands	12 Months Ended
RESTRUCTURING - Rollforward (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Restructuring Plan 2018
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning	$ 1,192
Charges	2,699
Cash payments	(1,610)
Non-cash settlement and other	(2,281)
Restructuring reserve, ending	0
Restructuring Plan 2018 \| Redundancy and Employee Severance and Benefits
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning	904
Charges	2,699
Cash payments	(1,610)
Non-cash settlement and other	(1,993)
Restructuring reserve, ending	0
Restructuring Plan 2018 \| Lease Loss Reserves and Contractual Obligations
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning	288
Charges	0
Cash payments	0
Non-cash settlement and other	(288)
Restructuring reserve, ending	0
Restructuring Plan 2016
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning	1,591
Non-cash settlement and other	(1,591)
Restructuring reserve, ending	0
Restructuring Plan 2016 \| Redundancy and Employee Severance and Benefits
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning	0
Non-cash settlement and other	0
Restructuring reserve, ending	0
Restructuring Plan 2016 \| Asset impairments
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning	0
Non-cash settlement and other	0
Restructuring reserve, ending	0
Restructuring Plan 2016 \| Lease Loss Reserves and Contractual Obligations
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning	1,591
Non-cash settlement and other	(1,591)
Restructuring reserve, ending	$ 0

DEBT - Long-term debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total carrying amount of debt	$ 330,865	$ 105,543
Less: current portion of convertible notes and long-term financing receivable recorded as debt	(325,967)	(2,884)
Long-term debt	4,898	102,659
Convertible Notes \| Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Long-term debt, gross	320,000	0
Less unamortized discount and issuance costs	(64,979)	0
Total carrying amount of debt	255,021	0
Less: current portion of convertible notes and long-term financing receivable recorded as debt	(255,000)
Convertible Notes \| Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Long-term debt, gross	88,140	132,000
Less unamortized discount and issuance costs	(19,119)	(35,815)
Total carrying amount of debt	69,021	96,185
Less: current portion of convertible notes and long-term financing receivable recorded as debt	(69,000)
Convertible Notes \| Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Long-term debt, gross	5,000	5,000
Less unamortized discount and issuance costs	(102)	(143)
Total carrying amount of debt	4,898	4,857
Financing Receivable \| Financing Receivable Recorded as Debt
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,925	$ 4,501

DEBT - Convertible Senior Notes due in 2025 Narrative (Details)			12 Months Ended
	Mar. 09, 2020 USD ($) trading_day $ / shares shares	Jun. 05, 2019 USD ($)	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($)	May 20, 2020 USD ($) $ / shares shares	May 19, 2020 shares	Mar. 31, 2020 USD ($)
Debt Instrument [Line Items]
Debt, current			$ 325,967,000	$ 2,884,000
Common stock, par value (in usd per share) \| $ / shares			$ 0.00001	$ 0.00001		$ 0.00001
Common stock, shares authorized (in shares) \| shares			200,000,000	150,000,000		200,000,000	150,000,000
Deferred tax assets, net			$ 92,904,000	$ 74,531,000
Payment for bonds hedge			89,056,000	36,313,000	$ 0
Proceeds from sale of warrants		$ 29,800,000	71,552,000	$ 29,818,000	$ 0
Warrants obligations measured at fair value						$ 96,400,000
Convertible Notes
Debt Instrument [Line Items]
Convertible notes embedded derivative						117,100,000
Convertible Notes \| Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Debt instrument face amount	$ 320,000,000							$ 320,000,000
Interest rate	0.25%							0.25%
Conversion ratio	0.0122637
Debt conversion price (in USD per share) \| $ / shares	$ 81.54
Proceeds from convertible debt	$ 313,000,000.0
Debt, current			255,000,000.0
Convertible notes embedded derivative	68,700,000					116,300,000
Embedded derivative, host contract	251,300,000
Deferred tax assets, net			$ 200,000
Debt issuance costs	$ 7,600,000
Effective percentage rate			5.18%
Unamortized discount			$ 58,600,000
Remaining discount amortization period			4 years 2 months 12 days
Conversion shares (in shares) \| shares	3,900,000
Payment for bonds hedge	$ 89,100,000
Warrants issued, strike price (in USD per share) \| $ / shares	$ 106.94
Proceeds from sale of warrants	$ 71,600,000
Warrants obligations measured at fair value	$ 71,552,000					$ 96,351,000
Period One \| Convertible Notes \| Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Number of threshold trading days \| trading_day	20
Number of consecutive trading days \| trading_day	30
Threshold percentage	130.00%
Stock trigger price (in USD per share) \| $ / shares			$ 106.00
Period Two \| Convertible Notes \| Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Number of consecutive trading days \| trading_day	5
Threshold percentage	100.00%
Measurement period percentage of stock price trigger	98.00%

DEBT - Convertible Note Embedded Derivative (Details) $ in Thousands	2 Months Ended
	May 20, 2020 USD ($)
Debt Instrument [Line Items]
Embedded derivative, change in the fair value	$ 47,600
Convertible Notes
Debt Instrument [Line Items]
Embedded derivative, ending balance	117,100
Convertible Notes \| Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Embedded derivative, beginning balance	68,700
Embedded derivative, ending balance	$ 116,300

DEBT - Schedule of Convertible Senior Notes due in 2025 (Details) - Convertible Notes - Convertible Senior Notes Due 2025 $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Contractual interest expense	$ 649
Amortization of debt discount	10,072
Amortization of debt issuance costs	1,229
Total interest cost recognized	$ 11,950

DEBT - Convertible Notes Hedge and Warrant Liability (Details) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended				12 Months Ended
	May 20, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Convertible notes hedge, change in the fair value		$ 0	$ 0	$ (59,692)	$ 15,344	$ (44,348)	$ 0	$ 0
Warrants liability, ending balance	$ 96,400
Convertible Notes \| Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Convertible notes hedge, beginning balance	89,056
Convertible notes hedge, change in the fair value	28,052
Convertible notes hedge, ending balance	117,108
Warrants liability, beginning balance	71,552
Warrants liability, change in fair value	24,799
Warrants liability, ending balance	$ 96,351

DEBT - Convertible Senior Notes due 2024 Narrative (Details) $ / shares in Units, shares in Millions			1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 09, 2020 trading_day	Jun. 05, 2019 USD ($) trading_day $ / shares shares	Feb. 12, 2021 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2020 USD ($) trading_day $ / shares shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Debt, current				$ 325,967,000	$ 325,967,000	$ 2,884,000
Deferred tax assets, net				92,904,000	92,904,000	74,531,000
Write off of debt discount				8,900,000
Write off of deferred debt issuance cost				800,000
Loss on extinguishment of debt					0	2,152,000	$ 0
Payment for bonds hedge					89,056,000	36,313,000	0
Proceeds from sale of warrants		$ 29,800,000			71,552,000	29,818,000	0
Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Loss on extinguishment of debt					3,037,000	0	$ 0
Convertible Notes \| Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Debt instrument face amount		$ 132,000,000.0		88,100,000	88,100,000
Interest rate		1.00%
Debt conversion price (in USD per share) \| $ / shares		$ 20.5010
Proceeds from convertible debt		$ 128,000,000.0
Conversion ratio		0.0487781
Debt, current				69,000,000.0	69,000,000.0
Convertible note, liability component		$ 95,600,000		37,200,000	37,200,000
Convertible note, equity component		36,400,000		6,700,000	6,700,000
Deferred tax assets, net		300,000
Debt issuance costs		4,600,000
Unamortized debt issuance costs		3,300,000		1,500,000	1,500,000	2,900,000
Debt issuance costs, allocated to capital		$ 1,300,000
Debt converted				43,900,000
Debt converted, settled				$ 38,500,000	$ 38,500,000
Conversion shares (in shares) \| shares				1.9
Equity component of convertible notes due 2025, net				$ 301,000,000.0
Loss on extinguishment of debt				$ 3,000,000.0
Effective percentage rate				7.75%	7.75%
Unamortized discount				$ 17,600,000	$ 17,600,000	$ 32,900,000
Remaining discount amortization period					3 years 4 months 24 days
Conversion shares (in shares) \| shares		6.4		4.3	4.3
Payment for bonds hedge		$ 36,300,000
Debt conversion, issuable (in shares) \| shares				2.1
Warrants sold (in shares) \| shares		6.4
Warrants issued, strike price (in USD per share) \| $ / shares		$ 25.2320
Convertible Notes \| Convertible Senior Notes Due 2024 \| Discount rate
Debt Instrument [Line Items]
Measurement input		0.0775		0.0575	0.0575
Convertible Notes \| Convertible Senior Notes Due 2024 \| Expected Term
Debt Instrument [Line Items]
Measurement input				3.6	3.6
Period One \| Convertible Notes \| Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Number of threshold trading days \| trading_day		20			20
Number of consecutive trading days \| trading_day					30
Stock trigger price (in USD per share) \| $ / shares					$ 26.6513
Threshold percentage					130.00%
Measurement period percentage of stock price trigger		98.00%
Period Two \| Convertible Notes \| Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Number of consecutive trading days \| trading_day	5
Threshold percentage		100.00%
Forecast \| Subsequent Event \| Convertible Notes \| Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Conversion of debt			$ 61,500,000

DEBT - Schedule of Convertible Senior Notes due 2024 (Details) - Convertible Notes - Convertible Senior Notes Due 2024 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Contractual interest expense	$ 1,284	$ 759
Amortization of debt discount	6,325	3,492
Amortization of debt issuance costs	646	375
Total interest cost recognized	$ 8,255	$ 4,626

DEBT - Convertible Senior Notes due 2023 Narrative (Details) - Convertible Senior Notes Due 2023		1 Months Ended
	Jun. 05, 2019 USD ($) shares	Aug. 31, 2018 USD ($) $ / shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Conversion shares (in shares) \| shares	10,801,080
Fees paid for repurchase and exchange of convertible notes	$ 6,000,000.0
Convertible Notes
Debt Instrument [Line Items]
Debt instrument face amount		$ 65,000,000.0	$ 5,000,000.0	$ 5,000,000.0
Interest rate		4.00%
Debt converted	$ 60,000,000.0
Debt conversion price (in USD per share) \| $ / shares		$ 5.56
Conversion ratio		0.1800180
Redemption price percentage		100.00%

DEBT - Schedule of Convertible Senior Notes due 2023 (Details) - Convertible Notes - Convertible Senior Notes Due 2023 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Contractual interest expense	$ 200	$ 1,226
Amortization of debt issuance costs	40	245
Total interest cost recognized	$ 240	$ 1,471

DEBT - Sale of Long - Term Financing Receivables (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Proceeds from debt, net of issuance costs		$ 0	$ 0	$ 68,024
Financing Receivable \| Financing Receivable Recorded As Debt
Debt Instrument [Line Items]
Proceeds from debt, net of issuance costs	$ 2,800			$ 5,600
Long-term debt, gross		$ 1,925	$ 4,501

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 26, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Term of lease contract, maximum renewal term	12 years
Purchase obligation	$ 162,200,000
Letters of credit outstanding	0
Letter of credit
Line of Credit Facility [Line Items]
Line of credit			$ 44,700,000
Section 301 Tariff Refunds
Line of Credit Facility [Line Items]
Potential positive impact of approval of requested Tariff refunds		$ 38,900,000
Tariff refund	24,800,000
Tariff refund receivable	14,700,000
Recognized in current period	38,900,000
Section 301 Tariff Refunds, Accrued Interest
Line of Credit Facility [Line Items]
Potential positive impact of approval of requested Tariff refunds		$ 600,000
Recognized in current period	$ 600,000

COMMITMENTS AND CONTINGENCIES - Lease Expense Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating lease costs	$ 5,332	$ 4,041

COMMITMENTS AND CONTINGENCIES - Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating lease liabilities, current (Accrued liabilities)	$ 4,542	$ 3,170
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Operating lease liabilities, noncurrent (Other liabilities)	$ 15,209	$ 9,542
Total operating lease liabilities	$ 19,751	$ 12,712
Weighted average remaining lease term	6 years 4 months 24 days	5 years 6 months
Weighted average discount rate	7.70%	8.60%
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent

COMMITMENTS AND CONTINGENCIES - Supplemental Cash Flow and Other Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating cash flows from operating leases	$ 4,762	$ 3,636
Lease liabilities arising from obtaining right-of-use assets	$ 10,625	$ 4,834

COMMITMENTS AND CONTINGENCIES - Schedule of Minimum Lease Payments Under Noncancelable Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2021	$ 5,830
2022	4,677
2023	4,056
2024	3,069
2025	2,275
2026 and thereafter	3,968
Total lease payments	23,875
Less: imputed lease interest	(4,124)
Total lease liabilities	$ 19,751	$ 12,712

SALE OF COMMON STOCK (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	1 Months Ended	12 Months Ended
	Feb. 28, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Number of shares issued (in shares)	9.5
Price per share issued (in usd per share)	$ 2.10
Proceeds from issuance of common stock	$ 20,000	$ 0	$ 0	$ 19,766

STOCK-BASED COMPENSATION Narrative (Details)				12 Months Ended
STOCK-BASED COMPENSATION Narrative (Details)	Jan. 01, 2021 shares	May 18, 2017 shares	Mar. 29, 2012 shares	Dec. 31, 2020 USD ($) purchasePeriod shares	Dec. 31, 2019 shares	Dec. 31, 2018 shares	Dec. 31, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, outstanding (in shares)				2,532,000	4,097,000	6,772,000	8,426,000
Total unrecognized compensation cost \| $				$ 89,700,000
Weighted-average recognition period for unrecognized compensation cost				2 years 10 months 24 days
2006 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, vesting period				4 years
Share-based compensation, weighted-average remaining contractual term				10 years
Share-based compensation, outstanding (in shares)				100,000
2011 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, vesting period				4 years
Share-based compensation, shares authorized (in shares)				2,643,171
Increase in common stock shares reserved for future issuance percentage				4.50%
Share-based compensation, shares available for grant (in shares)				8,940,388
Share-based compensation, additional shares authorized (in shares)				5,803,296
Employee Stock Purchase Plan (ESPP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, shares authorized (in shares)			669,603
Share-based compensation, shares available for grant (in shares)				1,288,887
Share-based compensation, additional shares authorized (in shares)		400,000
Share-based compensation, evergreen shares (in shares)		700,000	330,396
Share-based compensation, increase in number of shares authorized			1.00%
Employee stock purchase plan, number of interim purchase periods \| purchasePeriod				4
General duration of employee stock purchase plan				24 months
Share-based compensation, maximum employee subscription rate				15.00%
Share-based compensation, purchase price of common stock percent to fair market value				85.00%
Share-based compensation, look-back feature				2 years
IRS limitation for employees right to acquire class common stock under ESPP \| $				$ 25,000
Before August 1, 2012 \| 2011 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, weighted-average remaining contractual term				10 years
After August 1, 2012 \| 2011 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, weighted-average remaining contractual term				7 years
Subsequent Event \| Employee Stock Purchase Plan (ESPP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, evergreen shares (in shares)	700,000

STOCK-BASED COMPENSATION - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 42,503	$ 20,176	$ 11,432
Income tax benefit included in the provision for incomes taxes	61,389	8,185	0
Total unrecognized compensation cost	$ 89,700
Weighted-average recognition period for unrecognized compensation cost	2 years 10 months 24 days
Stock options and RSUs and PSUs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 39,841	19,216	10,691
Employee stock purchase plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	2,662	960	741
Cost of revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	3,759	1,650	1,071
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	12,701	4,897	2,940
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	11,548	5,678	3,074
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	14,495	7,216	4,347
Restructuring
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 0	$ 735	$ 0

STOCK-BASED COMPENSATION - Summary of Stock-Based Compensation Expense Associated with Each Type of Award (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 42,503	$ 20,176	$ 11,432
Stock options and RSUs and PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	39,841	19,216	10,691
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,662	$ 960	$ 741

STOCK-BASED COMPENSATION - Summary of the Weighted-Average Grant Date Fair Value of Options Granted (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
The fair value of each option granted during the periods
Grants in period (in shares)	11	43	213
Stock options
The fair value of each option granted during the periods
Weighted average grant date fair value (in usd per share)	$ 38.45	$ 9.16	$ 2.83
Expected term	3 years 9 months 18 days	3 years 9 months 18 days	4 years
Expected volatility	86.40%	89.10%	88.50%
Annual risk-free rate of return	0.10%	2.10%	2.60%
Dividend yield	0.00%	0.00%	0.00%

STOCK-BASED COMPENSATION - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Shares Outstanding
Outstanding, beginning balance (in shares)	4,097	6,772	8,426
Granted (in shares)	11	43	213
Exercised (in shares)	(1,494)	(2,616)	(1,346)
Canceled (in shares)	(82)	(102)	(521)
Outstanding, ending balance (in shares)	2,532	4,097	6,772
Shares outstanding, vested and expected to vest (in shares)	2,532
Shares outstanding, exercisable (in shares)	2,089
Weighted- Average Exercise Price per Share
Outstanding, beginning balance (in usd per share)	$ 2.18	$ 1.76	$ 1.77
Granted (in usd per share)	64.17	14.58	4.43
Exercised (in usd per share)	2.74	1.22	1.75
Canceled (in usd per share)	6.94	4.07	2.94
Outstanding, ending balance (in usd per share)	1.96	$ 2.18	$ 1.76
Weighted-average exercise price, vested and expected (in usd per share)	1.96
Weighted-average exercise price, exercisable (in usd per share)	$ 1.95
Weighted-Average Remaining Contractual Term
Outstanding	3 years 8 months 12 days
Vested and expected to vest	3 years 8 months 12 days
Exercisable	3 years 8 months 12 days
Aggregate Intrinsic Value
Exercised	$ 114,089	$ 31,093	$ 5,096
Outstanding	439,268
Vested and expected to vest	439,268
Exercisable	$ 362,526
Share price (in usd per share)	$ 175.47

STOCK-BASED COMPENSATION - Summary of Stock Options Outstanding (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding, number of shares (shares) \| shares	2,532
Options outstanding - weighted- average remaining life	3 years 8 months 12 days
Options outstanding - weighted- average exercise price (usd per share)	$ 1.96
Options exercisable - number of shares exercisable (shares) \| shares	2,089
Options Exercisable - weighted-average exercise price (usd per share)	$ 1.95
$0.70 —– $1.11
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (usd per share)	0.70
Exercise price range, upper limit (usd per share)	$ 1.11
Options outstanding, number of shares (shares) \| shares	555
Options outstanding - weighted- average remaining life	4 years 2 months 12 days
Options outstanding - weighted- average exercise price (usd per share)	$ 0.85
Options exercisable - number of shares exercisable (shares) \| shares	448
Options Exercisable - weighted-average exercise price (usd per share)	$ 0.83
$1.29 —– $1.29
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (usd per share)	1.29
Exercise price range, upper limit (usd per share)	$ 1.29
Options outstanding, number of shares (shares) \| shares	1,000
Options outstanding - weighted- average remaining life	3 years 8 months 12 days
Options outstanding - weighted- average exercise price (usd per share)	$ 1.29
Options exercisable - number of shares exercisable (shares) \| shares	813
Options Exercisable - weighted-average exercise price (usd per share)	$ 1.29
$1.31 —– $1.31
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (usd per share)	1.31
Exercise price range, upper limit (usd per share)	$ 1.31
Options outstanding, number of shares (shares) \| shares	670
Options outstanding - weighted- average remaining life	3 years 3 months 18 days
Options outstanding - weighted- average exercise price (usd per share)	$ 1.31
Options exercisable - number of shares exercisable (shares) \| shares	587
Options Exercisable - weighted-average exercise price (usd per share)	$ 1.31
$1.37 —– $14.58
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (usd per share)	1.37
Exercise price range, upper limit (usd per share)	$ 14.58
Options outstanding, number of shares (shares) \| shares	296
Options outstanding - weighted- average remaining life	3 years 7 months 6 days
Options outstanding - weighted- average exercise price (usd per share)	$ 5.56
Options exercisable - number of shares exercisable (shares) \| shares	235
Options Exercisable - weighted-average exercise price (usd per share)	$ 6.37
$64.17 —– $64.17
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price range, lower limit (usd per share)	64.17
Exercise price range, upper limit (usd per share)	$ 64.17
Options outstanding, number of shares (shares) \| shares	11
Options outstanding - weighted- average remaining life	6 years 3 months 18 days
Options outstanding - weighted- average exercise price (usd per share)	$ 64.17
Options exercisable - number of shares exercisable (shares) \| shares	6
Options Exercisable - weighted-average exercise price (usd per share)	$ 64.17

STOCK-BASED COMPENSATION - Summary of Restricted Stock Unit Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Aggregate Intrinsic Value
Share price (in usd per share)	$ 175.47
Restricted stock units
Number of Shares Outstanding
Outstanding, beginning balance (in shares)	4,263	4,352	3,505
Granted (in shares)	1,550	2,112	3,152
Vested (in shares)	(2,085)	(1,707)	(1,399)
Canceled (in shares)	(140)	(494)	(906)
Outstanding, ending balance (in shares)	3,588	4,263	4,352
Number of shares outstanding, expected to vest (in shares)	3,588
Weighted Average Fair Value per Share at Grant Date
Outstanding, beginning balance (in usd per share)	$ 7.19	$ 3.52	$ 2.03
Granted (in usd per share)	55.66	11.50	4.45
Vested (in usd per share)	7.26	3.87	2.75
Canceled (in usd per share)	19.47	4.81	2.17
Outstanding, ending balance (in usd per share)	27.61	$ 7.19	$ 3.52
Weighted-Average Fair Value per Share at Grant Date, Expected to vest (in usd per share)	$ 27.61
Weighted-Average Remaining Contractual Term
Outstanding	1 year 29 days
Expected to vest	1 year 29 days
Aggregate Intrinsic Value
Vested	$ 125,578	$ 27,156	$ 6,657
Outstanding	629,633
Aggregate intrinsic value, expected to vest	$ 629,633

STOCK-BASED COMPENSATION - Summary of Performance Stock Unit Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Aggregate Intrinsic Value
Share price (in usd per share)	$ 175.47
Performance shares
Number of Shares Outstanding
Outstanding, beginning balance (in shares)	955	1,330	0
Granted (in shares)	989	1,052	1,477
Vested (in shares)	(1,450)	(1,063)	0
Canceled (in shares)	0	(364)	(147)
Outstanding, ending balance (in shares)	494	955	1,330
Weighted Average Fair Value per Share at Grant Date
Outstanding, beginning balance (in usd per share)	$ 9.83	$ 4.66
Granted (in usd per share)	31.12	9.48	4.65
Vested (in usd per share)	10.20	4.62
Canceled (in usd per share)	0	5.16
Outstanding, ending balance (in usd per share)	$ 51.10	$ 9.83	$ 4.66
Weighted-Average Remaining Contractual Term
Weighted average remaining contractual term	2 months 12 days
Aggregate Intrinsic Value
Vested	$ 52,144	$ 10,818
Outstanding	$ 86,668

STOCK-BASED COMPENSATION - Summary of ESPP Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Proceeds from common stock issued under ESPP	$ 4,304	$ 1,692	$ 397
Shares of common stock issued (shares)	347	315	439
Weighted-average price per share (usd per share)	$ 12.41	$ 5.37	$ 0.90

INCOME TAXES - Schedule of Domestic and Foreign Components of Loss before Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
United States									$ 112,727	$ 85,520	$ (14,322)
Foreign									6,683	4,594	4,093
Income (loss) before income taxes	$ 71,352	$ 44,845	$ (53,855)	$ 57,068	$ 44,421	$ 31,371	$ 11,209	$ 3,113	$ 119,410	$ 90,114	$ (10,229)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68072869&loc=d3e41242-110953

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(10))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(8))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 235
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-URI http://asc.fasb.org/extlink&oid=120399901&loc=d3e537907-122884

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

INCOME TAXES - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal									$ 0	$ 0	$ 0
State									636	327	42
Foreign									1,896	1,589	1,233
Total									2,532	1,916	1,275
Deferred:
Federal									(13,445)	(56,959)	(35)
State									(3,672)	(17,458)	(21)
Foreign									0	1,467	179
Total									(17,117)	(72,950)	123
Income taxes (benefit) provision	$ (1,639)	$ 5,483	$ (6,561)	$ (11,868)	$ (72,245)	$ 272	$ 591	$ 348	$ (14,585)	$ (71,034)	$ 1,398

INCOME TAXES - Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income tax (benefit) provision at statutory federal rate									$ 25,076	$ 18,929	$ (2,148)
State taxes, net of federal benefit									(3,098)	(17,197)	17
Change in valuation allowance									0	(71,300)	8,198
Foreign tax rate and tax law differential									611	1,206	313
Tax credits									(5,835)	(1,803)	(378)
Stock-based compensation									(50,818)	(8,072)	(953)
Other permanent items									(253)	31	235
Other nondeductible/nontaxable items									1,525	2,765	(5,112)
Uncertain tax positions									1,530	504	107
GILTI									0	1,086	917
Section 162(m)									11,469	2,817	202
Warrant mark-to-mark adjustment									5,208	0	0
Income tax (benefit) provision	$ (1,639)	$ 5,483	$ (6,561)	$ (11,868)	$ (72,245)	$ 272	$ 591	$ 348	$ (14,585)	$ (71,034)	$ 1,398

INCOME TAXES - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Allowances and reserves	$ 13,146	$ 10,726
Net operating loss and tax credit carryforwards	53,116	54,369
Stock-based compensation	4,598	3,753
Deferred revenue	20,765	16,736
Fixed assets and intangibles	8,706	2,720
Sec. 163(j) interest carryforward	4,401	0
Other	7,007	1,109
Subtotal	111,739	89,413
Total deferred tax assets	111,739	89,413
Deferred tax liabilities:
Goodwill	(1,719)	(1,368)
Unremitted foreign earnings	(7)	(5)
Deferred cost of goods sold	(17,545)	(14,374)
Total deferred tax liabilities	(19,271)	(15,747)
Net deferred tax asset	$ 92,468	$ 73,666

INCOME TAXES - Narrative (Details) $ in Millions	12 Months Ended
INCOME TAXES - Narrative (Details) $ in Millions	Dec. 31, 2020 USD ($)
Tax Credit Carryforward [Line Items]
Unrecognized tax benefits	$ 1.8
Domestic Tax Authority
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	113.7
Domestic Tax Authority \| Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	18.2
State and Local Jurisdiction
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	87.3
State and Local Jurisdiction \| Research Tax Credit Carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 12.6

INCOME TAXES - Schedule of Reconciliation of Total Amounts of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits—at beginning of year	$ 6,589	$ 6,325	$ 6,106
Decreases in balances related to tax positions taken in prior years	0	(370)	0
Increases in balances related to tax positions taken in current year	2,006	771	329
Lapses in statutes of limitations	(174)	(137)	(110)
Unrecognized tax benefits—at end of year	$ 8,421	$ 6,589	$ 6,325

CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS (Details)		12 Months Ended
	Aug. 09, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue, Major Customer [Line Items]
Percentage of concentration risk	100.00%
Accounts Receivable, Largest Customer \| Accounts receivable \| Credit concentration risk
Revenue, Major Customer [Line Items]
Percentage of concentration risk		36.00%	34.00%
Accounts Receivable, Second Largest Customer \| Accounts receivable \| Credit concentration risk
Revenue, Major Customer [Line Items]
Percentage of concentration risk			14.00%
Accounts Receivable, Third Largest Customer \| Accounts receivable \| Credit concentration risk
Revenue, Major Customer [Line Items]
Percentage of concentration risk			11.00%
Net Revenues, Largest Customer \| Customer concentration risk
Revenue, Major Customer [Line Items]
Percentage of concentration risk				19.00%
Net Revenues, Largest Customer \| Net revenue \| Customer concentration risk
Revenue, Major Customer [Line Items]
Percentage of concentration risk		29.00%	21.00%
Net Revenue, Second Largest Customer \| Net revenue \| Customer concentration risk
Revenue, Major Customer [Line Items]
Percentage of concentration risk			12.00%

NET INCOME PER SHARE - Schedule of Computation of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net income (loss)	$ 72,991	$ 39,362	$ (47,294)	$ 68,936	$ 116,666	$ 31,099	$ 10,618	$ 2,765	$ 133,995	$ 161,148	$ (11,627)
Notes due 2023 interest and financing costs, net									177	1,088	0
Adjusted net income (loss)									$ 134,172	$ 162,236	$ (11,627)
Denominator:
Weighted average common shares outstanding (in shares)									125,561	116,713	99,619
Employee stock-based awards (in shares)									6,997	8,964	0
Weighted average common shares outstanding for diluted calculation (in shares)									141,918	131,644	99,619
Net income per share, basic (in USD per share)	$ 0.57	$ 0.31	$ (0.38)	$ 0.56	$ 0.95	$ 0.25	$ 0.09	$ 0.03	$ 1.07	$ 1.38	$ (0.12)
Net income per share, diluted (in USD per share)	$ 0.50	$ 0.28	$ (0.38)	$ 0.50	$ 0.88	$ 0.23	$ 0.08	$ 0.02	$ 0.95	$ 1.23	$ (0.12)
Convertible Senior Notes Due 2024
Denominator:
Warrants (issued in conjunction with Notes due 2024) (in shares)									4,011	0	0
Convertible Notes \| Convertible Senior Notes Due 2024
Denominator:
Notes due (in shares)									4,449	451	0
Convertible Notes \| Convertible Senior Notes Due 2023
Denominator:
Notes due (in shares)									900	5,516	0

NET INCOME PER SHARE - Schedule of Potentially Dilutive Securities Excluded from the Computation of Diluted Net Income Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,494	485	24,684
Employee stock-based awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	7	27	7,710
RSU's and PSU's
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	36	158	5,273
Warrants \| Convertible Senior Notes Due 2024
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	300	0
Warrants \| Convertible Senior Notes Due 2025
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,254	0	0
Notes due \| Convertible Senior Notes Due 2025
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	197	0
Notes due \| Convertible Senior Notes Due 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	0	11,701

NET INCOME PER SHARE - Narrative (Details) - Convertible Notes - $ / shares	Mar. 09, 2020	Jun. 05, 2019
Convertible Senior Notes Due 2024
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Debt conversion price (in USD per share)		$ 20.5010
Convertible Senior Notes Due 2025
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Debt conversion price (in USD per share)	$ 81.54

SEGMENT AND GEOGRAPHIC INFORMATION - Narrative (Details)	12 Months Ended
	Dec. 31, 2020 segment
Segment Reporting [Abstract]
Number of reportable segments	1
Number of operating segments	1

SEGMENT AND GEOGRAPHIC INFORMATION - Summary of Long-Lived Assets by Geographic Region (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 42,985	$ 28,936
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	19,870	16,754
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	9,948	4,635
Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	4,808	3,510
India
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	4,371	1,315
New Zealand
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	3,837	2,638
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 151	$ 84

RELATED PARTY - Narrative (Details) - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Aug. 31, 2018
SunPower’s
Related Party Transaction [Line Items]
Common stock issued for business acquisition (in shares)	3.5	6.5
Revenue from related parties		$ 70,900,000
Accounts receivable, related parties		15,900,000
Safe harbor prepayments		5,200,000
Convertible Notes \| Convertible Senior Notes Due 2023
Related Party Transaction [Line Items]
Debt instrument face amount	$ 5,000,000.0	5,000,000.0		$ 65,000,000.0
Thurman John Rodgers \| Convertible Notes \| Convertible Senior Notes Due 2023
Related Party Transaction [Line Items]
Debt instrument face amount	$ 5,000,000.0	$ 5,000,000.0	$ 5,000,000.0

ACQUISITION - Narrative (Details) - USD ($) $ in Thousands, shares in Millions		3 Months Ended	12 Months Ended
	Aug. 09, 2018	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Consideration transferred for business acquisition	$ 57,319
Common stock issued	32,319
Goodwill		$ 24,783	$ 24,783	$ 24,783
Cash purchase price allocated in cash flows from operating activities			(25,568)	(14,788)	$ (19,151)
Cash purchase price allocated in cash flows from investing activities			216,334	139,067	16,132
Acquisition funded by issuance of common stock			$ 0	$ 0	19,219
Cash Purchase Price	25,000
Customer relationship
Business Acquisition [Line Items]
Consideration transferred for business acquisition	23,100
Common stock issued	13,100
Cash Purchase Price	10,000
Developed Technology And Goodwill
Business Acquisition [Line Items]
Consideration transferred for business acquisition	34,219
Common stock issued	19,219
Cash Purchase Price	$ 15,000
SunPower’s
Business Acquisition [Line Items]
Agreement for exclusive supplier rights, period	5 years	3 months
Consideration transferred for business acquisition	$ 57,319
Common stock issued for business acquisition (in shares)	7.5
Common stock issued	$ 32,319
Limitation for trade or transfer, period	6 months
Limitation for number of shares to be transferred by acquiree, period	6 months
Goodwill	$ 21,119
Amortization period for acquired intangible assets	15 years
Cash purchase price allocated in cash flows from operating activities					10,000
Purchase price					25,000
Cash purchase price allocated in cash flows from investing activities					15,000
Acquisition funded by issuance of common stock					19,200
Cash Purchase Price	$ 25,000				15,000
Total acquisition related costs					$ 800
SunPower’s \| Developed technology
Business Acquisition [Line Items]
Amortization period for acquired intangible assets	6 years
SunPower’s \| Customer relationship
Business Acquisition [Line Items]
Amortization period for acquired intangible assets	9 years
Discount rate \| SunPower’s \| Minimum
Business Acquisition [Line Items]
Equity, measurement input	30.00%
Discount rate \| SunPower’s \| Maximum
Business Acquisition [Line Items]
Equity, measurement input	14.00%

ACQUISITION - Summary of Consideration Transferred for Business Acquisition (Details) - USD ($) $ in Thousands		12 Months Ended
	Aug. 09, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Cash consideration	$ 25,000
Common stock issued	32,319
Total	57,319
SunPower’s
Business Acquisition [Line Items]
Cash consideration	25,000	$ 15,000
Common stock issued	32,319
Total	57,319
Developed technology and goodwill
Business Acquisition [Line Items]
Cash consideration	15,000
Common stock issued	19,219
Total	34,219
Customer relationship
Business Acquisition [Line Items]
Cash consideration	10,000
Common stock issued	13,100
Total	$ 23,100

ACQUISITION - Summary of Fair Values of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Aug. 09, 2018
Business Acquisition [Line Items]
Goodwill	$ 24,783	$ 24,783
SunPower’s
Business Acquisition [Line Items]
Intangible assets			$ 36,200
Goodwill			21,119
Net assets acquired			$ 57,319

ACQUISITION - Summary of Identifiable Intangible Assets Acquired (Details) - SunPower’s $ in Thousands	Aug. 09, 2018 USD ($)
Business Acquisition [Line Items]
Intangible assets	$ 36,200
Useful Life	15 years
Developed technology
Business Acquisition [Line Items]
Intangible assets	$ 13,100
Useful Life	6 years
Customer relationship
Business Acquisition [Line Items]
Intangible assets	$ 23,100
Useful Life	9 years

ACQUISITION - Summary of Allocation of Purchase Price to Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands		12 Months Ended
	Aug. 09, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Cash Purchase Price	$ 25,000
Issuance of Common Stock	32,319
Total	$ 57,319
% of Total Consideration	100.00%
SunPower’s
Business Acquisition [Line Items]
Cash Purchase Price	$ 25,000	$ 15,000
Issuance of Common Stock	32,319
Total	57,319
Developed technology and goodwill
Business Acquisition [Line Items]
Cash Purchase Price	15,000
Issuance of Common Stock	19,219
Total	$ 34,219
% of Total Consideration	60.00%
Customer relationship
Business Acquisition [Line Items]
Cash Purchase Price	$ 10,000
Issuance of Common Stock	13,100
Total	$ 23,100
% of Total Consideration	40.00%

SUBSEQUENT EVENTS - Narrative (Details) - USD ($) $ in Thousands			1 Months Ended	12 Months Ended
	Jan. 25, 2021	Aug. 09, 2018	Jan. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Payments to acquire investments				$ 5,010	$ 0	$ 0
Consideration transferred for business acquisition		$ 57,319
Subsequent Event
Subsequent Event [Line Items]
Payments to acquire investments			$ 25,000
Subsequent Event \| Sofdesk
Subsequent Event [Line Items]
Voting interests acquired	100.00%
Consideration transferred for business acquisition	$ 32,000

SELECTED UNAUDITED QUARTERLY FINANCIAL INFORMATION - Schedule of Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Net revenues	$ 264,839	$ 178,503	$ 125,538	$ 205,545	$ 210,032	$ 180,057	$ 134,094	$ 100,150	$ 774,425	$ 624,333	$ 316,159
Cost of revenues	142,901	83,522	77,151	124,870	132,151	115,351	88,775	66,811	428,444	403,088	221,714
Gross profit	121,938	94,981	48,387	80,675	77,881	64,706	45,319	33,339	345,981	221,245	94,445
Operating expenses:
Research and development	15,801	15,052	13,192	11,876	11,168	11,085	9,604	8,524	55,921	40,381	32,587
Sales and marketing	14,139	14,645	12,371	11,772	10,690	9,551	9,054	7,433	52,927	36,728	27,047
General and administrative	12,884	13,525	11,970	12,315	10,450	9,895	8,583	9,880	50,694	38,808	29,086
Restructuring charges					1,131	469	631	368	0	2,599	4,129
Total operating expenses	42,824	43,222	37,533	35,963	33,439	31,000	27,872	26,205	159,542	118,516	92,849
Income from operations	79,114	51,759	10,854	44,712	44,442	33,706	17,447	7,134	186,439	102,729	1,596
Interest income	673	110	282	1,091	815	894	593	211	2,156	2,513	1,058
Interest expense	(5,901)	(5,993)	(5,952)	(3,155)	(2,303)	(2,286)	(1,351)	(3,751)	(21,001)	(9,691)	(10,693)
Other income (expense)	(2,534)	(1,031)	653	(924)	1,467	(943)	(5,480)	(481)	(3,836)	(5,437)	(2,190)
Change in fair value of derivatives	0	0	(59,692)	15,344					(44,348)	0	0
Total other expense, net	(7,762)	(6,914)	(64,709)	12,356	(21)	(2,335)	(6,238)	(4,021)	(67,029)	(12,615)	(11,825)
Income (loss) before income taxes	71,352	44,845	(53,855)	57,068	44,421	31,371	11,209	3,113	119,410	90,114	(10,229)
Income tax benefit (provision)	1,639	(5,483)	6,561	11,868	72,245	(272)	(591)	(348)	14,585	71,034	(1,398)
Net income (loss)	$ 72,991	$ 39,362	$ (47,294)	$ 68,936	$ 116,666	$ 31,099	$ 10,618	$ 2,765	$ 133,995	$ 161,148	$ (11,627)
Net income per share, basic (in USD per share)	$ 0.57	$ 0.31	$ (0.38)	$ 0.56	$ 0.95	$ 0.25	$ 0.09	$ 0.03	$ 1.07	$ 1.38	$ (0.12)
Net income per share, diluted (in USD per share)	$ 0.50	$ 0.28	$ (0.38)	$ 0.50	$ 0.88	$ 0.23	$ 0.08	$ 0.02	$ 0.95	$ 1.23	$ (0.12)

Label	Element	Value
Accounting Standards Update [Extensible List]	us-gaap_AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201409Member

- Definition

Indicates amendment to accounting standards.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (f)(2)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (g)(1)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 65
-Paragraph 15
-Subparagraph (f)(2)
-URI http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 10
-Section 65
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 65
-Paragraph 15
-Subparagraph (f)(1)
-URI http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(i)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 65
-Paragraph 15
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 10
-Section 65
-Paragraph 4
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 65
-Paragraph 15
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 10
-Section 65
-Paragraph 4
-Subparagraph (e)(3)
-URI http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 65
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(iv)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(iii)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 65
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 65
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333

Reference 24: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 10
-Section 65
-Paragraph 4
-Subparagraph (e)(4)
-URI http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 10
-Section 65
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 65
-Paragraph 15
-Subparagraph (g)(2)
-URI http://asc.fasb.org/extlink&oid=121322162&loc=SL121327923-165333

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (f)(1)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 10
-Section 65
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121646688&loc=SL121648383-210437

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 65
-Paragraph 2
-Subparagraph (g)(2)(ii)
-URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 65
-Paragraph 8
-Subparagraph (d)(2)

Reference 32: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 65
-Paragraph 8
-Subparagraph (d)(3)

+ Details