Solar Panel Size Calculator
Find out how many solar panels — and what system size in kW — you need to cover your home's electricity use.
Panels needed
20
400W each
System size
7.6 kW
Est. monthly use
900 kWh
Est. annual output
10800 kWh
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How many panels does a house need?
The number of panels depends on three things: how much electricity you use, how much sun your location gets, and the wattage of the panels. The calculator sizes a system to offset your annual usage, then divides by your panel wattage to get a panel count.
Rule of thumb
A typical US home uses about 900 kWh per month. In an average-sun location that's roughly a 7–9 kW system, or about 18–23 panels at 400W each. Sunnier states need fewer panels for the same output.
Get free solar quotes
Compare local installers — no obligation.
Get free solar quotes