Solar Loan Calculator for Monthly Payment and APR Cost

Solar Loan Calculator

Estimate your monthly payment and total interest, with accurate 2026 tax rules — no phantom tax-credit paydown.

System cost

Down payment

APR

Term

yrs

Financing solar without paying cash up front

Most US homeowners go solar with a loan rather than a lump-sum payment, and for good reason: a well-structured loan lets you own your system while spreading the cost over manageable monthly payments that are often lower than the utility bill they replace. This calculator shows what that payment looks like — and reflects the post-2025 tax landscape so the numbers are honest.

The tax-credit paydown trick — and what changed in 2026

Through 2025, solar lenders advertised strikingly low monthly payments built on a specific assumption: that you would take your 30% federal tax credit and apply it as a one-time payment against the loan principal within the first 12 to 18 months, then let the loan re-amortize to a lower payment. That credit (Section 25D) ended on December 31, 2025, so for systems bought in 2026 there is no credit to apply and no paydown step — the advertised "low payment" no longer materializes. Our calculator reflects this: enter a 2025 in-service year to see the historical paydown, or leave the default and see the true 2026 payment with no credit applied. Beware any 2026 quote that still promises a tax-credit paydown.

Term length, interest, and the real cost

A longer term lowers your monthly payment but increases the total interest you pay over the life of the loan, while a shorter term does the opposite. Some solar loans also carry a dealer fee baked into the financed amount, which is why a 0.99% headline rate can cost more than a higher-rate loan with no fee. Use the APR your lender actually quotes, and watch how the total-interest figure responds as you change the term.

Loan, lease, or cash?

Cash delivers the most savings by avoiding interest entirely, and a loan trails only by the interest you pay. But here is a 2026 twist: now that homeowner purchases no longer get the federal credit while third-party-owned leases and PPAs can still capture it through the commercial 48E credit, the gap between owning and leasing has narrowed for some households. Run the same system through our Lease vs Buy vs PPA comparison to see which path now wins for you.

Frequently asked questions

How do solar loans work?

A solar loan finances your system so you pay it off in fixed monthly installments instead of one lump sum. You own the system and keep all the energy savings. Note: as of 2026, owner-occupied purchases no longer receive the federal tax credit, which ended Dec 31, 2025.

What is the ITC paydown on a solar loan?

Through 2025, lenders advertised low payments assuming you would apply your 30% tax credit to principal within 12–18 months. With the credit ended for 2026 purchases, there is no paydown for new systems — be wary of any 2026 quote that still promises one. Our calculator shows the historical paydown only when you model a 2025 in-service year.

What APR is typical for solar loans?

Solar loan APRs commonly range from about 4% to 9% depending on credit, term, and any dealer fees. Longer terms lower the monthly payment but raise total interest.

Is a solar loan better than a lease in 2026?

It is closer than it used to be. With the homeowner credit gone but leases/PPAs still able to capture federal value via the 48E credit, the ownership advantage has narrowed. A loan still builds equity and avoids escalators; a lease offers zero upfront cost and no maintenance. Compare them in our Lease vs Buy tool.

Does a solar loan affect my taxes?

For 2026 purchases there is no federal solar credit to claim. Interest on a solar loan secured by your home may still be deductible — consult a tax professional.