Panels needed by peak sun hours
| Sun hours (region) | System size | 400 W panels | Roof area |
|---|---|---|---|
| 3.5 h (Pacific NW) | 21.8 kW | 55 | 1,182 sq ft |
| 4.0 h (Northeast) | 19.1 kW | 48 | 1,032 sq ft |
| 4.5 h (Midwest) | 17.0 kW | 43 | 924 sq ft |
| 5.0 h (Southeast) | 15.3 kW | 39 | 838 sq ft |
| 5.5 h (Texas, Florida) | 13.9 kW | 35 | 752 sq ft |
| 6.0 h (Colorado, SoCal) | 12.7 kW | 32 | 688 sq ft |
| 6.5 h (Arizona, Nevada) | 11.8 kW | 30 | 645 sq ft |
Formula: 2,000 kWh ÷ 30.42 days ÷ (sun hours × 0.86). Check your exact sun hours with NREL PVWatts.
Frequently asked questions
How much does a 17.0 kW system produce per year?
About 23,997 kWh per year at 4.5 sun hours.
Do bigger panels mean fewer panels?
Yes. With 450 W panels you would need 38 instead of 43.