RV solar panel roof fit calculator
Check how many identical rectangular panels fit a clear roof section. Compare a regular grid in either orientation, allowing for gaps and an edge margin.
First size solar from daily energy. Then measure an unobstructed rectangle that excludes vents, air conditioners, access paths, and their required clearances. Do not enter total roof area minus obstacle area: obstacle positions matter.
Measure the clear rectangle and actual panels
Formula and assumptions
usable span = roof span − 2 × edge margin
panels along span = floor((usable span + gap) ÷ (panel span + gap))
grid count = panels along length × panels across widthRepeat after rotating every panel 90 degrees and take the larger count. Gaps occur between panels, not beyond the last panel. This tool compares two uniform grids; it does not optimize mixed orientations or irregular roof shapes. Exact fits leave no extra installation tolerance.
Worked example
A clear 180 × 96 in rectangle, 58 × 26 in panels, a 2 in edge margin, and 1 in gaps gives 176 × 92 in usable space. The as-entered grid fits 3 × 3 = 9 panels; the rotated grid fits 6 × 1 = 6. Nine 200 W panels total 1,800 W nameplate capacity.
Roof fit FAQ
Can I subtract the air conditioner's area from roof area?
No. A vent in the middle can prevent a panel from fitting even if total remaining area is large. Measure clear rectangles around obstacles, maintain required access and clearances, and avoid counting overlapping sections twice.
Does a fitting panel mean the roof can support it?
No. Verify roof structure, panel and mounting weight, wind loads, attachment points, cable routing, access, and the RV and mounting manufacturers' instructions.
Could mixed orientations fit more panels?
Yes. This is a quick two-grid comparison, not an optimal packing solver. Use a scaled drawing or a mounting professional for complex layouts.