Solar ROI Calculator

Estimate your U.S. solar system size, cost, and payback period based on your state and electricity usage. According to the U.S. National Renewable Energy Laboratory NSRDB (National Solar Radiation Database, 2024 release) and the DSIRE U.S. Database of State Incentives, the U.S. has more than 5,000,000 active residential solar installations as of 2024, with average annual solar irradiance ranging from 3.5 to 6.5 kWh/m²/day across all 50 states. See our methodology for the exact NREL irradiance + DSIRE incentive parameters.

Enter your details above to see a solar ROI estimate for your state.

Estimates use NREL solar resource data, EIA electricity rates, and Wood Mackenzie/SEIA installed cost averages.

How the PlainSolarData Calculator Works

This calculator is an educational tool. It takes the inputs you provide, applies a documented formula, and shows the result along with the intermediate steps where those steps are useful for understanding. The formula is published on the methodology page so you can verify it, reproduce it on paper, or implement it yourself. We do not use the calculator to collect personal data — inputs are processed client-side or, when server-side, are not associated with any account or profile.

When the Calculator Is Reliable

The calculator is most accurate when the inputs you enter reflect your actual situation and when the formula we use matches the regulatory or industry standard you are trying to approximate. It is less reliable when your situation contains a non-standard factor — an exception, a waiver, a grandfathered term, or a jurisdiction-specific variant — that the public formula does not express. When in doubt, treat the calculator's output as an order-of-magnitude estimate, not a binding number. For legal, medical, financial, tax, or safety decisions, verify with a licensed professional.

What We Do Not Do

We do not tune calculator outputs for commercial reasons, do not shade them upward or downward to flatter a sponsor, and do not run A/B tests on the formula to improve engagement at the cost of accuracy. When we update the formula — for example, to reflect a new regulatory threshold or a new reference rate — we publish the change on the methodology page along with the effective date, so that anyone citing an earlier calculation can still find the prior formula.

Privacy and Your Inputs

By default, calculator inputs are processed in your browser and never leave the device. A small number of calculators require a server round-trip (for example, to look up a rate from a public dataset); those requests are logged only in the same aggregate fashion as any other page view. We do not build a profile from calculator usage, do not share inputs with advertisers, and do not retain inputs across sessions. If you would like your interaction logs disregarded entirely, browse privately or use a tracker-blocker — we respect both.