How to use the Solar Panel Roof Space Calculator
The Formula
Effective area = roof sq ft × usable %. Max panels = floor(effective area ÷ panel footprint). System kW = panels × panel watts ÷ 1,000.
Practical Example
Leave walkways for maintenance and comply with fire setbacks. Pair with Solar Panel Size to match daily energy needs.
About Solar Panel Roof Space Calculator
How roof sizing works
Effective area = roof sq ft × usable %. Max panels = floor(effective area ÷ panel footprint). System kW = panels × panel watts ÷ 1,000.
Planning tips
Leave walkways for maintenance and comply with fire setbacks. Pair with Solar Panel Size to match daily energy needs.
Frequently asked questions
Q: What panel size should I use? A: Measure one module or use ~20 sq ft for modern 350–450 W panels. Q: Is every square foot usable? A: No—80% is a common planning factor.