SOLAR
How to Calculate Solar Panel Roof Area
Preliminary method for estimating the roof area needed to fit a set of solar panels.
The roof area needed is more than the sum of the panels. A gap factor for access and spacing between rows adds real square footage.
THE SHORT ANSWER
How do you calculate solar panel roof area?
Multiply panel count by panel area and a gap factor, then add each row gap times the row width. Twenty panels in four rows at the defaults need about 496 sq ft before accounting for roof obstructions and setbacks.
Know the panel footprint
Each panel has a set area. Multiply the panel count by that area for the bare footprint.
Apply a gap factor
Add a factor for walking space, cut margins and access. A 1.1 factor adds 10% to the footprint.
Add row spacing
Rows need space between them for wiring and access. More rows mean more spacing area.
- Panel footprint
- Gap factor
- Row spacing
- Rows
This is a preliminary layout
Use the Solar Panel Roof Area Calculator to plan, but a real layout needs professional design and permitting. These figures are planning only.