Solar Panel Payback Calculator
Wondering if rooftop solar is worth it? Our free solar panel payback calculator estimates your net installation cost after the federal tax credit, your yearly electricity savings, and how long it takes for the panels to pay for themselves — plus your estimated 25-year net savings.
Enter your numbers
Your results
| Federal tax credit value | — |
|---|---|
| Estimated monthly savings | — |
| Simple 25-year net savings (estimate) | — |
| 25-year net savings with rate growth (estimate) | — |
How to use this calculator
Start with your installer's quoted system cost — the full price before any incentives. Then enter the federal tax credit rate you qualify for (30% is the current default in the U.S.; adjust it if your situation differs). Add your average monthly electric bill and the share of it you expect the panels to offset.
Results update instantly as you type, so you can play with scenarios: what if your bill only drops 80%? What if installation costs $22,000 instead of $18,000? The annual utility rate increase is optional but realistic — electricity prices have historically risen a few percent per year, and it only feeds the 25-year savings estimate, never the payback period.
How it works
Net cost is your system cost minus the federal credit: net cost = system cost × (1 − credit rate). Your first-year savings are your annual bill times your offset share: annual savings = monthly bill × 12 × offset %. The simple payback period is net cost ÷ annual savings — the years until your savings have covered what you paid.
For the long view we show two 25-year estimates (a typical panel warranty period). The simple version is annual savings × 25 − net cost, assuming rates never change. The growth version compounds your savings at the utility rate increase you entered: Σ annual savings × (1 + rate)ᵗ − net cost over 25 years. Both are clearly labeled estimates: they ignore panel degradation (roughly 0.5% per year), inverter replacement, maintenance, and changes to net metering rules. They are planning aids, not quotes.
Frequently asked questions
How does the federal solar tax credit affect the payback period?
The federal Investment Tax Credit lets you subtract a percentage of your system cost — the default here is 30% — from your federal taxes. On an $18,000 system that is $5,400, so your net cost is $12,600. Because the payback period is net cost divided by yearly savings, the credit shortens it substantially. The calculator applies the credit to your gross system cost before dividing by your annual electricity savings.
What makes a solar payback period shorter or longer?
The three biggest drivers are your system cost per watt, your electricity rate, and how much of your bill the panels offset. High utility rates and a large offset shorten the payback period, while shading, a north-facing roof, or a low electric bill lengthen it. Local rebates and net metering rules can also improve the math.
Is 100% bill offset realistic?
Sometimes. A well-sized system on a sunny, unshaded roof can offset most or all of your usage, but net metering policies, panel degradation of about 0.5% per year, and seasonal production swings mean many homeowners see 70% to 90% offset. Lower the offset percentage if you expect partial coverage, and always get a quote from a local installer before deciding.
Are the 25-year savings figures guaranteed?
No — they are estimates, not guarantees. The 25-year figure assumes your first-year savings grow at the annual utility rate increase you enter, and it ignores maintenance costs like inverter replacement, panel degradation, and changes in net metering rules. Actual savings vary with your location, roof, installer pricing, and future electricity prices.