StraightWatt

Calculators / Solar panel cost calculator

What will solar cost me?

Installed cost has two defensible answers that differ by roughly 60%. This shows both, because a reader quoted the higher one deserves to have seen it here first.

Price, then net cost

Two numbers matter and they are far apart. The gross price is the size of the system multiplied by the installed cost per watt in your state. The net cost is what is left after the credits you can actually claim — which in 2026 is a shorter list than most calculators still assume, because the federal residential credit is no longer available to a buyer. What changed and when.

Everything between those two numbers is itemised above, with the statute or programme each deduction comes from. A credit is not a rebate: it offsets tax you owe, so a household with no federal or state liability receives nothing from a credit regardless of what the headline percentage says.

Why the two bases differ by so much

The gap is methodology, not staleness. A marketplace observes competitive bids; a national survey of installed systems observes every sale, including the door-to-door and financed channels where prices run well above the competitive market. Neither number is wrong. They answer different questions, and which one you get depends entirely on how you buy.

We publish both, use the quoted basis in the tables, and label every payback figure on the site as resting on it. The reasoning is on the methodology page, and the state-by-state comparison is in what solar costs in 2026.

What to do with the number

Questions

Why are there two prices?
Because two credible sources measure two different things. Quote marketplaces publish the price of competitive bids from installers who know they are being compared. Laboratory research on installed systems reports what buyers actually paid, across every channel including the ones that never quote against anyone. Both are honest, they differ by roughly 60%, and a calculator that shows only the lower one is telling you what solar could cost rather than what it does.
Which price should I plan on?
Plan on the higher one and be pleased if you beat it. The tables on this site use the quoted basis, so every payback figure here is the optimistic case; the alternative is shown beside it on every page for exactly that reason. If your quotes land near the reported basis, that is normal, not a bad deal.
Does the price include everything?
It includes panels, inverter, racking, labour, permitting and the installer margin - everything in the installed price. It excludes two costs the model handles separately because they arrive later: routine maintenance each year, and an inverter replacement around year twelve. Those come off the savings rather than the price. A new roof, a panel upgrade or a trenched run to a detached garage are not modelled at all.
Why is the price per watt higher on a small system?
Because much of the cost does not scale. Permitting, design, the site visit and a crew for a day cost about the same for a four-kilowatt system as for an eight, so the fixed share is spread over fewer watts. Published per-watt figures are averages across all sizes, so a small system will usually quote above them.

The other calculators

All of them run the same engine on the same data, so two can never disagree. They differ in what they put first.

A screening estimate from published data, not a quote and not tax or financial advice. Every input is listed under the results with the source it came from and the date it was read; the formulas are on the methodology page. Confirm against real quotes, and with a professional, before relying on any figure here.

Published 6 September 2026. Data last verified 6 September 2026. Rates: EIA 2026-07. Found a figure that looks wrong? Tell us — we publish corrections.