Before you ask for solar quotes, it helps to know roughly how many panels your roof can hold. This free roof solar panel fit estimator turns your roof size and a panel size into a panel count and a total system size in kilowatts.
Enter the roof length and width in feet, an edge margin, and the panel length, width, and watts. The tool subtracts the margin from every edge, because panels cannot sit right at the edge of a roof, then tries both panel directions and keeps the one that fits more panels.
A typical home panel is about 67 by 40 inches and rated around 400 watts. On a 40 by 20 foot roof with a 1.5 foot margin, about 33 such panels fit, giving roughly 13 kilowatts. Your roof and your panel choice will change that number, so try a few panel sizes.
The panel count is only the first step. Real output also depends on direction, tilt, shading from trees and chimneys, and your local sunshine. A south-facing roof with no shade produces far more than the same panels on a shaded or north-facing roof.
Roof shape matters too. This tool assumes one plain rectangle. Vents, skylights, chimneys, and valleys all take space away, and some roofs need a structural check before they can carry panel weight. Fire setback rules also vary by area and can change the usable area.
This estimator is educational only. Real fit depends on roof shape, vents, chimneys, shading, roof strength, and local codes. A solar installer must survey your roof before you buy or build, and they can also tell you the expected yearly output for your location.
Use the estimate to compare quotes sensibly: if one installer promises far more panels than fit on your roof, ask how. It is free and needs no sign-up.
Pingback: Estimador de Paneles Solares para Tejado - Cuántos Paneles Caben en tu Cubierta