Suncipher

Solar Roof Calculator

Find out how many panels — and how large a system — your roof can actually fit.

This tells you what your roof can physically fit. Want the system size recommended for your actual usage instead? See the Solar Size Calculator.
This tool provides a planning estimate based on the assumptions shown below the results — it is not a quote, and actual costs and savings will vary by installer, local rates, and your specific home.
sq ft

Measure the roof section(s) with good sun exposure — south, east, or west-facing.

%

Fire code setbacks, roof vents, chimneys, and valleys typically claim about 30% of a roof — 70% is a reasonable default.

W
sq ft

Enter your roof area to see the maximum system it can support.

How this calculator works

Effective usable area = total roof area × usable-share percentage. Max panel count = effective usable area ÷ one panel's footprint, rounded down. Max system size = panel count × panel wattage.

This tells you what your roof can physically hold — pair it with our Solar Size Calculator to check whether that's enough to meet your actual usage.

Source: DOE Homeowner's Guide to Going Solar; NREL PVWatts methodology, last updated 2026-07-01.