Solar Loan Calculator 2026: Monthly Payment & Interest
Calculate your 2026 solar loan payment, total interest and year-1 cash flow vs bill savings, with an optional lump-sum paydown. No federal credit assumed.
Estimate scope & data quality
- SEO Quick Estimate Uses the inputs available in this calculator.
- Personalized Estimate Use your own bill and location information where this calculator supports it.
- Detailed Solar Economics NOT_COMPUTABLE here without a verified tariff, system design, quote, and eligibility record.
- Data quality
- NOT_AVAILABLE
- Result limitation
- Calculator output is not a source-complete customer result.
A tariff credit is distinct from annual savings. If a result is NOT_COMPUTABLE or CONFLICT, it must not be replaced with an estimate or treated as canonical.
How to use this calculator
- Enter the installed system cost (this site uses a blended $3.00/W; an 8 kW system is about $24,000). No federal credit is subtracted for 2026 installs.
- Set the loan term and the APR from your lender quote.
- Set the down payment percentage (many solar loans are $0 down).
- Optionally enter a lump-sum paydown, such as a state or utility rebate or your own savings, applied at month 12.
- Enter your monthly electric bill to compare the loan payment with estimated year-1 bill savings.
Understanding your results
Short answer: In 2026, a $24,000 solar system (8 kW at $3.00/W) financed with $0 down at 6.99% APR for 12 years costs about $247 a month, $35,522 in total payments and $11,522 in interest. There is no federal credit to pay the loan down, so compare that payment with realistic bill savings: about $9 a month in year 1 for a $150 bill at a 0.75 offset.
How solar loan payments are calculated: Monthly payment = P × r(1+r)^n / ((1+r)^n − 1), where P is the loan amount, r is the monthly interest rate (APR ÷ 12) and n is the number of months. At $24,000, 6.99% APR and a 12-year term, r = 0.5825% and n = 144, so the payment is $246.68.
The old ITC paydown strategy no longer applies: Until Dec 31, 2025, homeowners could claim 30% of the system cost under §25D, and many loans assumed that refund would be applied to principal around month 12–18. The One Big Beautiful Bill Act (Public Law 119-21, signed July 4, 2025) ended §25D for systems installed after Dec 31, 2025. The calculator now uses an optional lump-sum paydown instead, for a state or utility rebate or your own savings. Paying $5,000 at month 12 in the example drops the payment to about $192 and saves about $2,180 in interest. This is not tax advice; confirm with a tax professional.
Year-1 cash flow: Bill savings = monthly bill × 12 × 0.75 (the US blended bill offset; about 0.87 with full-retail net metering, 0.55–0.70 with weaker export rules). Savings then grow roughly 2.5% a year as rates rise 3% and panels degrade 0.5%. A negative monthly cash flow during the loan is common in 2026; the payoff comes after the loan ends.
Solar loan types: (1) Unsecured solar loans: quick approval, no home lien, often with dealer fees built into the price. (2) Home equity loan or HELOC: usually lower rates, uses your home as collateral, slower approval. (3) PACE financing where available: repaid through property taxes, but it can complicate a sale or refinance. (4) Cash: no interest and the fastest payback.
Cash vs loan vs lease: Cash has no interest cost. A loan preserves savings but adds interest ($11,522 in the example). A lease or PPA needs no upfront money, and the lessor may still claim the §48E business credit through 2027 and pass some value through, but there is no guaranteed discount. Use the lease vs buy calculator to compare the actual quotes.
Frequently asked questions
Direct answers for US homeowners.
Related guides
In-depth articles on sizing, costs, and energy decisions.