Everything on this site — the calculator, the tables, the guides — is an estimate built on assumptions we print next to it. Provided as-is, for planning; not for contracts.

Modeled output, not a site survey

Production figures come from the general formula kW × sun-hours × orientation × performance — the same first-pass model every estimator uses, with honest midpoints where installers would use a roof-specific survey. Your irradiance, your micro-shading, your soiling and your equipment differ from any midpoint. Where a quote, a PVWatts run with your address, or a meter disagrees with this site, they are right.

Incentive and tariff information is dated, not eternal

We write incentive status with dates because it expires — e.g., the §25D residential credit ended for installs completed after December 31, 2025, and we say so as of the article’s stamped date. Statutes change; proposals to restore credits circulate; tariffs reprice every year. The dated statement was true when written — verify current law against IRS.gov, DSIRE and your utility before relying on any figure, including ours.

Not financial, tax, legal or engineering advice

Nothing here is a substitute for licensed professionals. Tax credits and deductions depend on your liability and your facts — a CPA or enrolled agent, not a web calculator. Structural load, roof warranty, electrical interconnection and permitting belong to licensed engineers, contractors and your AHJ. Financing comparisons are arithmetic; whether to take a loan or lease is your decision with your numbers.

Accuracy is a range, and we say so

Payback years printed here carry the uncertainty of every input: sun hours ±, losses ±, your effective rate ±, escalation ±, and everything not modeled at all (maintenance, inverter replacement, insurance, roof work, rate-design changes). Treat results as honest planning ranges — useful for comparing options, insufficient for signing $20,000 contracts on.

Advertising

The site may show third-party ads (e.g. Google AdSense) to offset hosting. Advertisers have no access to your inputs (there are none on our side — see privacy) and no influence on the math or the articles.

Liability

Use of this site is at your own risk. To the maximum extent permitted by law, SolarCalc and its maintainers accept no liability for losses connected with its use — including purchases justified by estimated savings, contracts informed by dated incentive status, and work undertaken from our tables. Verify any number that costs money or touches your roof against current primary sources and licensed professionals.