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Fair Value | 12 Months Ended
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Dec. 31, 2025
Fair Value Disclosures [Abstract] |
Fair Value | Fair Value Our accounting policy for the fair value measurement of cash equivalents is described in Note 2—Summary of Significant Accounting Policies in this Annual Report on Form 10-K. Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis The tables below set forth, by level, our financial assets and liabilities that are accounted for at fair value for the respective periods. The table does not include assets and liabilities that are measured at historical cost or any basis other than fair value (in thousands):
|  | Fair Value Measured at Reporting Date Using
December 31, 2025 |  | Level 1 |  | Level 2 |  | Level 3 |  | Total
Assets |  |  |  |  |  |  |  |
Cash equivalents: |  |  |  |  |  |  |  |
Money market funds |  | $ | 2,386,583 |  |  | $ | — |  |  | $ | — |  |  | $ | 2,386,583 |
Liabilities |  |  |  |  |  |  |  |
Derivatives: |  |  |  |  |  |  |  |
Embedded EPP derivatives |  | $ | — |  |  | $ | — |  |  | $ | 5,607 |  |  | $ | 5,607 |
|  | Fair Value Measured at Reporting Date Using
December 31, 2024 |  | Level 1 |  | Level 2 |  | Level 3 |  | Total
Assets |  |  |  |  |  |  |  |
Cash equivalents: |  |  |  |  |  |  |  |
Money market funds |  | $ | 749,358 |  |  | $ | — |  |  | $ | — |  |  | $ | 749,358 |
Liabilities |  |  |  |  |  |  |  |
Derivatives: |  |  |  |  |  |  |  |
Embedded EPP derivatives |  | $ | — |  |  | $ | — |  |  | $ | 5,070 |  |  | $ | 5,070 |
Money Market Funds—Money market funds are valued using quoted market prices for identical securities and are therefore classified as Level 1 financial assets. Embedded Escalation Protection Plan Derivative Liability in Sales Contracts—We estimate the fair value of the embedded EPP derivatives in certain sales contracts using a Monte Carlo simulation model, which considers various potential electricity price curves over the sales contracts’ terms. We use historical grid prices and available forecasts of future electricity prices to estimate future electricity prices. We have classified these derivatives as Level 3 financial liability. The changes in the Level 3 financial liabilities during the years ended December 31, 2025, 2024 and 2023, were as follows (in thousands):
| Embedded EPP Derivative Liability
Liabilities at December 31, 2023 | $ | 4,376 |
Changes in fair value | 694 |
Liabilities at December 31, 2024 | 5,070 |
Changes in fair value | 537 |
Liabilities at December 31, 2025 | $ | 5,607 |
To estimate the liabilities related to the EPP contracts, an option pricing method was implemented through a Monte Carlo simulation, which considers various potential electricity price forward curves over the sales contracts’ terms. We use historical grid prices and available forecasts to estimate future electricity prices. The grid pricing EPP guarantees that we provided in some of our sales arrangements represent an embedded derivative, with the initial value accounted for as a reduction in product revenue and any changes, reevaluated quarterly, in the fair market value of the derivative recorded in Loss on revaluation of embedded derivatives. The unobservable inputs were simulated based on the available values for avoided cost and cost of electricity as calculated for December 31, 2025 and 2024, using an expected growth rate of 7% over the contracts’ life and volatility of 15%. The estimated growth rate and volatility were estimated based on the historical tariff changes for the period 2008 to 2025. Avoided cost is the transmission and distribution cost expressed in dollars per kilowatt hours avoided in the given year of the contract, calculated using the billing rates of the effective utility tariff applied during the year to the host account for which usage is offset by the generator. If the billing rates within the utility tariff change during the measurement period, the average amount of charge for each rate shall be weighted by the number of effective months for each amount. The inputs listed above would have had a direct impact on the fair values of the EPP derivatives if they were adjusted. Generally, a decrease in electric grid prices would result in an increase in the estimated fair value of our EPP derivative liabilities. For the years ended December 31, 2025, 2024 and 2023, we recorded the fair value of the embedded EPP derivatives with no material unrealized gains or losses in either of the three years ended December 31, 2025, 2024 and 2023, in our consolidated statements of operations. The fair value of these derivatives was $5.6 million and $5.1 million as of December 31, 2025 and 2024, respectively. Financial Assets and Liabilities Not Measured at Fair Value on a Recurring Basis Debt Instruments—The term loans and convertible senior notes are based on rates currently offered for instruments with similar maturities and terms (Level 2). The following table presents the estimated fair values and carrying values of debt instruments (in thousands):
|  | December 31, 2025 |  | December 31, 2024
|  | Net Carrying Value |  | Fair Value |  | Net Carrying Value |  | Fair Value
Debt instruments |  |  |  |  |  |  |  |
Recourse: |  |  |  |  |  |  |  |
0% Convertible Senior Notes due November 2030 |  | $ | 2,442,091 |  |  | $ | 2,140,536 |  |  | $ | — |  |  | $ | — |
3.0% Green Convertible Senior Notes due June 2029 1 |  | 73,473 |  |  | 313,740 |  |  | 391,239 |  |  | 532,789 |
3.0% Green Convertible Senior Notes due June 2028 1 |  | 98,162 |  |  | 456,764 |  |  | 619,111 |  |  | 872,344 |
2.5% Green Convertible Senior Notes due August 2025 |  | — |  |  | — |  |  | 114,385 |  |  | 163,875 |
Non-recourse: |  |  |  |  |  |  |  |
4.6% Term Loan due October 2026 |  | 2,769 |  |  | 3,009 |  |  | 2,705 |  |  | 2,856 |
4.6% Term Loan due April 2026 |  | $ | 1,384 |  |  | $ | 1,550 |  |  | $ | 1,352 |  |  | $ | 1,482 |
1 The increase in fair value primarily reflects the rise in the Company’s stock price. On May 7, 2025, we entered into the Exchange Agreements with certain holders of our 2.5% Green Notes. Pursuant to the Exchange Agreements, $112.8 million in aggregate principal amount of the 2.5% Green Notes, and related accrued and unpaid interest, were exchanged for $115.7 million in aggregate principal amount of the 3.0% Green Notes due June 2029. As of August 15, 2025, the maturity date, the remaining $2.2 million aggregate principal amount of our 2.5% Green Notes outstanding following the Debt Exchange, was settled through the issuance of our Class A common stock. On November 4, 2025, we issued the 0% Notes in an aggregate principal amount of $2,500.0 million due November 2030, unless earlier repurchased, redeemed or converted, resulting in net cash proceeds of $2,440.2 million. Concurrently with the issuance of the 0% Notes, we entered into the Exchange Transactions with a limited number of holders of our existing convertible debt to exchange (i) $532.8 million principal amount of the 3.0% Green Notes due June 2028 for aggregate consideration consisting of $539.6 million in cash, including related accrued interest, and 24,302,183 shares of our Class A common stock, and (ii) $443.1 million principal amount of the 3.0% Green Notes due June 2029 for aggregate consideration consisting of $448.8 million in cash, including related accrued interest, and 18,105,762 shares of our Class A common stock. For details of the Debt Exchange, 2.5% Green Notes settlement, issuance of the 0% Notes and the Exchange Transactions, see Note 8—Outstanding Loans and Security Agreements in this Annual Report on Form 10-K.

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- 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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 107 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-107 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 100 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-100 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2E -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (h) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 940 -SubTopic 820 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478119/940-820-50-1 + Details
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