Solar Panel Count Calculator

Once you know the system size you are aiming for, the panel count is simple division: take the target in watts and divide by the wattage of the panel you plan to buy. A `400 W` panel is the common residential choice, but higher-output modules of `450` to `500 W` cut the count while smaller `350 W` panels raise it. Because you can only buy whole panels, the calculator always rounds up — a fractional panel still means one more module on the roof.

The second number this tool gives you is the physical area the array occupies. A typical crystalline-silicon residential module is about `1.95 m²` (roughly `21 sq ft`), so multiplying the panel count by that footprint tells you how much clear, unshaded roof or ground you need. The result switches between square feet and square meters with the unit toggle, and every figure is shown in both systems so the number travels with you.

Treat the area as the panels alone. A real installation needs extra room for fire-code setbacks from the ridge and edges, walkways, and gaps between rows, so plan on adding roughly a quarter more surface than the raw array area suggests.