How many solar panels fit on my roof?
Enter your available roof area to estimate the number of panels and the system size in kWp. For an exact, to-scale layout, design it from a single drone photo with RoofDecko.
Rough estimate using a ~1.95 m² module footprint and your usable-area assumption. Real layouts depend on roof shape, obstructions, setbacks, and orientation. Get an exact to-scale layout from a drone photo →
How the estimate works
The quick math: take your usable roof area, divide by the footprint of one panel (about 1.95 m² / 21 ft²), and you get a rough panel count. Multiply panels by the panel wattage to get system size in kWp. The “usable” factor matters a lot — chimneys, vents, hips and valleys, fire/access setbacks, and shading all reduce what you can actually fill, which is why real layouts usually land below the raw area estimate.
From estimate to exact layout
An area estimate is great for a first pass, but quoting needs the real thing. With RoofDecko you drop in one top-down drone photo, trace the roof facets, and paint panels to scale — with access clearances, auto-grouped arrays, NEC 690.7 string checks, and a kWp total you can put on a quote.
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FAQ
How many solar panels fit on my roof?
As a rule of thumb, divide your usable roof area by about 1.95 m² (roughly 21 ft²) per panel, then multiply by a usable-area factor (often 60–80%) to allow for setbacks, obstructions, and orientation. The calculator above does this for you and also estimates system size in kWp.
How much roof area does one solar panel need?
A typical residential panel is about 1.95 m² (~21 ft²), or roughly 1.13 m × 1.72 m. Modern panels are commonly 400–450 W, so each adds about 0.4–0.45 kWp.
How do I get an exact panel layout instead of an estimate?
Roof shape, obstructions, fire/access setbacks, and orientation all change the real number. RoofDecko produces a to-scale layout from a single top-down drone photo, including access clearances and NEC 690.7 string sizing — far more accurate than an area-based estimate.