How many solar panels for 1,500 kWh per month?
A transparent worked example for a high-usage home. Change the sun-hours, panel wattage, and roof assumptions in the calculator link below.
Technical feedback wanted: if the loss factor, sun-hours, or roof utilization looks off, copy the result summary or share link from the calculator and send the correction back.
Scenario
- Monthly electricity use: 1,500 kWh
- Daily electricity use: about 50 kWh/day
- Peak sun-hours assumption: 5.0 hours/day
- System loss factor: 20%
- Panel size: 400W residential panels
Calculation
Daily load
50 kWh
Estimated system
12.5 kW
400W panels
32 panels
Formula: 50 kWh/day divided by 5 sun-hours divided by 0.80 system efficiency = about 12.5 kW DC. With 400W panels, that is about 32 panels before roof layout constraints.
A 400W panel often needs roughly 18-20 sq ft. With spacing and roof setbacks, this example should be checked against usable roof area, not total roof area.
Open the editable calculator
This link preloads a 400W panel, 5.0 sun-hours, and enough roof area for about 32 panels. Change the roof area or panel wattage to test your own case.
If the assumptions feel off, copy the result summary or share link from the calculator and leave feedback on the estimate.