Number of Panels Calculator: Solar Tool

Estimate only.Confirm with a pro and get a real quote. A professional solar site assessment and a written installer quote are authoritative for final system size, production, and cost.

Screening result

Enter a system size or annual use to estimate panel count.

Fine Print and Sources

Estimate only. These tools use only the values you enter and simple planning math. Confirm with a pro and get a real quote. A professional solar site assessment and a written installer quote are authoritative for system sizing, production, and final purchase decisions.

Method: panels equal system watts divided by panel wattage, rounded up. Roof area uses about 18 sq ft per panel as a planning figure. Actual roof area depends on panel dimensions, spacing, setbacks, and obstructions.

EnergySage solar sizing guide: explains how annual electricity use, peak sun hours, and panel wattage drive system size and panel count.
NREL PVWatts calculator: a detailed production model that accounts for location, orientation, shading, and system losses.