Where the numbers in the calculators and state pages come from, how often they get rechecked, and what to do if one looks off.
The default price-per-watt figure loaded into the cost calculator is pulled from national residential solar pricing data, cross-checked against the Department of Energy's homeowner solar guide and industry installer surveys. It is a starting point, not a quote. Actual pricing swings with panel brand, roof complexity, labor cost in your area, and how competitive the local installer market is. We say as much on the calculator page itself.
The federal tax credit rate used across every calculator, the tax credit tool, the savings tool, and each state page, comes directly from the IRS page on the Residential Clean Energy Credit. When the IRS updates the rate or the expiration date, we update every page that cites it in the same pass, not one at a time.
Each of the fifty-one state and D.C. pages applies the same national pricing model with a state-level adjustment drawn from published regional installation cost data and, where available, state-specific incentive programs on top of the federal credit. The formula is the same from state to state; the inputs that change are local price per watt, average system size, and any state rebate or tax exemption layered on top of the 30% federal credit. We note when a state has no meaningful incentive beyond the federal credit rather than inventing one.
Pricing inputs and the credit rate get checked quarterly against the sources above. The full run of state pages gets a complete pass at least once a year, usually after any IRS guidance update or a meaningful shift in national installer pricing. A reader-flagged error gets looked at as soon as it comes in rather than waiting for the scheduled pass.
If a number looks wrong for your state, or a page still shows a rate that changed, use the contact page and tell us which page and what you're seeing. We check every message. If a figure turns out to be stale, we fix it and note the update where it matters.
Calculators, guides, and state pages are written by Jessica Martinez, a home and finance writer. She is not an electrician, a licensed solar installer, or a tax preparer, and nothing here substitutes for advice from one. SolarPanelCostGuide is published by Chris Terry, who handles the technical and editorial oversight of the site; he does not write the cost content.
This site does not call installers to negotiate on a reader's behalf, does not sell leads, and does not accept payment to rank one installer or panel brand above another anywhere in its content. Every figure here is a planning number built from public sources, meant to prepare you for a real conversation with a licensed installer, not to replace one.