Solar Loan Calculator

Most dedicated solar lenders are quoting 5%–8% APR for homeowners with good credit (700+) in 2026. Credit unions and community banks sometimes offer rates on the lower end. Avoid dealer-arranged financing that bundles a higher rate into the system price — always ask for the APR separately. This calculator uses 5.99% as a default, which reflects a competitive market rate for a 15-year term.

Paying cash maximizes your total return — no interest means your ROI is purely the energy savings. However, if the loan rate is below your investment return rate, financing preserves capital for higher-yield uses. For most homeowners, the key question is cash flow: if the monthly savings cover the loan payment, financing a solar system costs very little in real terms. Run the Solar ROI Calculator alongside this tool to compare both scenarios.

A solar loan is an unsecured personal loan (no collateral) specifically for solar installations, typically offered by specialty solar lenders. Interest rates are usually fixed. A Home Equity Line of Credit (HELOC) is secured by your home — rates may be lower, but you risk your home if you default. HELOCs also have variable rates, which adds uncertainty to your monthly budget. Most homeowners prefer dedicated solar loans for the fixed payment and no-collateral structure.

The 15-year term is widely considered the sweet spot for residential solar loans. It keeps monthly payments affordable while ensuring the loan is paid off before panels approach end-of-warranty life (typically 25 years). A 20- or 25-year term lowers monthly payments further but means you'll be paying interest long after the system has proven its value. If cash flow is tight, start with a 20-year term and make extra principal payments when possible.

The federal residential solar tax credit (IRC §25D) expired on December 31, 2025. New installations in 2026 and beyond do not qualify. If your system was installed before that date and you receive an ITC refund, applying it as a lump-sum principal payment in year one can significantly reduce your total interest. For current installations, your loan should be sized to the full gross system cost. This calculator is not tax advice — consult a qualified tax professional for your specific situation.

A negative net cash flow during the loan term does not necessarily mean solar is a bad investment. Once the loan is paid off, 100% of your electricity savings become income — typically for 10–15 years after payoff. The total lifetime savings almost always exceed total loan costs, even in high-rate scenarios. However, if your monthly shortfall is large, consider a longer loan term or a larger down payment to bring the payment down. This calculator helps you find the combination where savings and payments balance.

Generally, interest on an unsecured solar loan is not tax-deductible — it is treated as personal interest under IRS rules. However, if you finance solar through a Home Equity Loan (HEL), Home Equity Line of Credit (HELOC), or cash-out mortgage refinance secured by your primary residence, the interest may be deductible if the proceeds are used to substantially improve the home — which solar installations typically qualify as. Deductions are subject to current mortgage interest deduction caps and require itemizing on Schedule A. Tax treatment depends on your specific situation; consult a licensed CPA or tax professional before assuming any deduction.

Unsecured solar loans — the most common type sold by specialty solar lenders — require no collateral. Approval depends on credit score and income, rates are typically fixed at 5–9% APR, and there is no risk to your home if you default (though it does damage your credit). Secured solar loans (HELOCs, home equity loans, PACE assessments) are backed by your home's equity. They often carry lower interest rates but put your home at risk of foreclosure if you default, and PACE in particular becomes a senior lien on your property that can complicate future home sales. Most homeowners prefer unsecured loans for the simpler structure.

Credit score is the primary driver of your offered rate. As of 2026, borrowers with FICO scores of 740+ typically see rates in the 5–6% APR range; scores of 680–739 see 6–8%; below 680 may see 9–13% or be limited to dealer-financed options with hidden fees. A 100-point credit-score swing can change your total interest cost on a 15-year $20,000 loan by $4,000–$7,000. If your score is borderline, consider waiting 6–12 months to improve it before financing, or pursue a HELOC if you have substantial home equity and prefer the lower-rate route.

Yes, most solar loans can be refinanced if rates drop or your credit improves. Refinancing options include rolling the balance into a new unsecured loan with a lower APR, paying it off with a HELOC for a lower secured rate, or — for owners with mortgage equity — folding it into a cash-out refinance. Watch for prepayment penalties on your existing loan (most modern solar loans have none, but PACE and some legacy loans do) and closing costs on the new loan, which can erase savings if the rate drop is only 0.5–1%. A 1.5%+ rate drop is generally where refinancing makes financial sense.

Treatment depends on the loan type. Unsecured solar loans are personal debt — you remain responsible for paying them off when you sell, and the loan does not transfer to the buyer. Most sellers pay them off at closing using sale proceeds; the system stays with the home and is reflected in the appraised value. HELOCs and home-equity-secured loans must be paid off at closing because they are tied to the property. PACE assessments are different and transfer with the property as a tax lien — which can complicate or even derail a sale because many mortgage lenders refuse properties with active PACE liens. Verify your loan structure before financing.