Solar roof layout
Estimate how many panels actually fit after roof dimensions, edge setbacks, vents, AC units, walk paths, and panel size are counted.
Quick roof fit read
9 panels at 200W each gives about 1,800W on the roof before real-world harvest derates.
Estimated fit
1,800W against a 600W target
Usable roof
192 sq ft gross before setbacks and keep-outs
Daily harvest
190A MPPT output target at 12V
Treat this as purchase screening. Final layout still needs tape-measure verification around vents, AC shrouds, roof curves, wire entry, and manufacturer mounting rules.
Start over
This calculator stores inputs locally in this browser. Clear saved inputs when stale values are getting in the way.
Roof-space calculator
Enter the roof, keep-outs, and panel size. The calculator estimates how many panels fit, whether the solar target is realistic, and what charge-controller target the roof array points toward.
Roof fit estimate
9 panels at 200W each gives about 1,800W on the roof before real-world harvest derates.
Estimated fit
9 panels
1,800W installed roof array
Usable roof
106.3 sq ft
192 sq ft gross before setbacks and keep-outs
Daily harvest
7.0 kWh
Uses 5 peak-sun hours and a 0.78 RV solar derate
MPPT output target
190A
Planning target at 12V before controller-specific limits
Panel orientation check
Portrait
9
Landscape
9
Used area
92%
Watch-outs
This is a planning estimate, not a roof attachment plan. Confirm rafters, membrane type, fasteners, sealant, wire routing, walk paths, and manufacturer mounting rules before drilling.
Obstructions are simplified into square feet, so odd-shaped roof items can still block panels even when the area math looks fine.
Recommended next move
Open the solar calculator next and check whether this roof wattage also covers daily loads and battery recovery.
Why this exists
Solar shopping usually starts with watts, but RV roofs are shaped by vents, air conditioners, skylights, curves, racks, and wire paths. This calculator checks fit before you fall in love with a panel that only works on paper.
Use this with
Solar calculator
Use this when you need to turn daily watt-hours into the solar target you are trying to fit.
Run the RV solar calculatorRV solar installation guide
Use this before drilling holes, choosing cable glands, or routing wires into the roof.
Read the RV solar installation guideRecharge time calculator
Use this when the roof target falls short and you need to compare recovery alternatives.
Run the recharge time calculatorTool notes
The output is a purchase-screening number. It tells you whether the panel size and target wattage deserve a detailed roof layout, not whether the installation is ready.
The calculator subtracts edge setbacks from the roof rectangle before removing obstruction allowance and layout buffer.
Portrait and landscape counts are estimated from the adjusted rectangle, then capped by the usable square-footage allowance.
Installed watts are converted into estimated daily harvest and an MPPT output-current target for the chosen battery voltage.
Avoid these traps
Two panels with similar wattage can have very different dimensions. A roof may fit four narrow panels but only two larger residential-style panels.
AC units, skylights, vents, antennas, curved edges, awning hardware, and walk paths all matter. The buffer is there because square-foot math is too optimistic by itself.
A panel fitting on paper does not confirm roof structure, membrane compatibility, mounting hardware, sealant, fusing, or wire routing.
Treat the calculator result as a planning range, then verify the relevant manufacturer guidance, safety limits, installation requirements, and local rules before changing the rig.See assumptions
Gear to compare after the math
These handoffs match the calculator family, not a one-click prescription. Verify fit, specs, clearances, and install limits before buying.
Rich Solar MEGA 200 Solar Panel
Best for
Expanding a roof-first array in 200W-class increments
Use this kind of panel when roof layout, controller limits, and wiring runs support adding more fixed wattage.
Current listing
Rich Solar MEGA 200 Solar Panel at Rich Solar.
Renogy 400W 12V Solar Premium Kit
Best for
A 400W starter kit when the calculator result is modest
Use this as a 400W kit, not a silent substitute for a larger array. For a 600W answer, treat it as the base kit plus another 200W panel and a fresh controller check.
Current listing
Renogy 400W 12V Solar Premium Kit at Renogy.
Victron SmartSolar MPPT 100/30
Best for
Controller planning for smaller RV solar arrays
A controller-class handoff for calculator results where panel wiring and current limits need a real hardware check.
Current listing
Victron SmartSolar MPPT 100/30 at Victron.
Frequently asked
No. It is a planning estimate before you buy panels. Final layout still needs tape-measure verification around every vent, AC unit, skylight, antenna, roof curve, and wire entry point.
Obstruction square footage handles obvious objects. The buffer covers awkward shapes, service access, wire routing, roof edges, brackets, and spacing that simple area math misses.
Use best-fit for early planning. Switch to portrait or landscape if the panel mounting rails, roof ribs, or wire path already force an orientation.
First test higher-wattage panels with real dimensions. If that still misses, compare portable solar, lower daily loads, alternator/DC-DC charging, or generator recovery instead of adding battery without a refill plan.