Reading your cash vs financed result
Why this comparison no longer includes a tax credit
The federal residential solar tax credit expired for systems installed after December 31, 2025. Both totals shown here reflect the full system price with no credit applied, which is the accurate picture for a 2026 purchase. If your system was installed by that deadline and you have unused credit carrying forward, the carried-forward credit tool covers that narrower situation. For general background on how financing decisions changed, see the DOE's homeowner's guide to solar financing.
Why financing costs more but rarely costs you more monthly
A financed system costs more in total because of interest, roughly 40% to 110% more than the cash total depending on the loan term, a wider gap than it was when the federal tax credit still applied. But the loan payment is usually close to or smaller than the monthly bill savings, so the actual out-of-pocket difference month to month can be small or even positive. The cash flow positive timeline calculator shows exactly when your bill savings start covering the full loan payment.
What "payback period" actually measures
For a cash purchase, payback is simply the total cost divided by annual savings, since there's no ongoing payment eating into that savings. A $28,000 system against $1,500 in annual savings pays back in about 18.7 years, longer than it would have been with the now-expired tax credit reducing the upfront cost. Financed payback is less clean, since the loan payment offsets savings until the loan ends, then the full savings amount becomes pure gain. The solar payback period calculator covers this same calculation from a slightly different angle.
When financing is the smarter move even with cash on hand
If your cash could earn more invested elsewhere than the loan's APR costs you, financing and investing the difference usually wins on paper, though it does carry investment risk that a paid-off system doesn't. This calculation only compares the solar costs directly. The financing cost vs cash savings comparison tool goes deeper into that opportunity-cost tradeoff. Before you sign a loan, the Consumer Financial Protection Bureau's report on solar financing is worth reading for its findings on dealer fees and loan terms.
How the loan term changes the picture
A 10-year loan pays off faster and costs far less in total interest than a 25-year loan, but carries a higher monthly payment that can exceed your bill savings in the early years. A 25-year loan keeps payments low and cash-flow-friendly but adds substantially more interest over time. Compare specific terms directly with the 10-year and 25-year loan calculators.
What this doesn't account for
This comparison assumes your annual bill savings figure holds steady, though real savings usually grow slightly as utility rates rise. It also doesn't include maintenance costs, which are minimal but not zero for either path. For a more complete lifetime view, check the total cost including financing fees tool. Borrow less by claiming first. The rebate stacking tool in our Rebates & Incentives section estimates the federal credit and rebates so you can size the loan to the net cost.