How many solar panels fit on your roof?

Type your address. We read your actual roof from Google's aerial imagery — real size, real shading, real sunlight hours — then show what a system would cost, save and pay back. Free, no email, no sales call.

We never store your address. Works best in the US, Canada and Europe.

What this actually tells you

Most solar calculators ask for a postcode and run an average. This one looks at your building. Google's Solar API analyses aerial and 3D imagery of the roof you typed in and returns its usable area, how many standard panels physically fit on it, and how many hours of usable sunlight it receives a year after shading from trees, chimneys and neighbouring buildings.

We take those numbers and apply straightforward economics: 400W panels, a 15% system loss for inverters, wiring, heat and dirt, an installed cost of $2.85 per watt, and your state or province's average electricity rate.

We also tell you when to install fewer panels. Filling every square metre of roof is usually a bad deal — you can't save more than you currently spend, so extra panels past your household's usage often never pay for themselves. We show a recommended size and the maximum, side by side, so you can see the difference.

Solar panel cost by city

We've run the same analysis across 209 cities using real rooftop samples from each one. Pick yours to see typical sunlight hours, system cost, payback period and 25-year return:

Solar panels in PhoenixArizona · cost & paybackSolar panels in Los AngelesCalifornia · cost & paybackSolar panels in HoustonTexas · cost & paybackSolar panels in MiamiFlorida · cost & paybackSolar panels in DenverColorado · cost & paybackSolar panels in Las VegasNevada · cost & paybackSolar panels in AustinTexas · cost & paybackSolar panels in San DiegoCalifornia · cost & paybackSolar panels in TorontoOntario · cost & paybackSolar panels in AtlantaGeorgia · cost & paybackSolar panels in SeattleWashington · cost & paybackSolar panels in VancouverBritish Columbia · cost & payback

See all 209 cities →

Common questions

How many solar panels does the average house need?

Most homes need 15 to 22 panels. A typical household uses about 10,800 kWh a year, and one 400W panel produces roughly 450–700 kWh a year depending on where you live. Sunnier places need fewer panels for the same result. Full breakdown →

Is my roof good for solar?

A good solar roof has unshaded area facing south (in the northern hemisphere), a pitch between 15° and 40°, and at least 10 more years of life left in it. Shading matters more than almost anything else — one badly placed tree can cut output by a third. How to check →

How much do solar panels cost in 2026?

About $2.85 per watt installed in the US before incentives, so roughly $17,100 for a 6 kW system or $28,500 for 10 kW. The 30% federal tax credit takes roughly a third off that. See the full cost breakdown →

How long do solar panels take to pay for themselves?

Six to ten years in most of the US, and longer where electricity is cheap or sunlight is scarce. Payback is driven far more by your electricity rate than by how sunny it is — Hawaii and California pay back fastest because power there is expensive. See payback by state →

PanelFit is an independent tool. We do not sell solar panels, we are not paid by installers, and we do not pass your address to anyone. Figures are modelled estimates for research — always get real quotes before buying.