Solar panels needed for 1,100 kWh per month
26 panels
of 400 W (10.2 kW) cover 1,100 kWh/month at 4.5 peak sun hours · about $28,519 before the 30% credit at $2.80/W
System size by peak sun hours
| Peak sun hours | System size | 400 W panels | Roof area |
|---|---|---|---|
| 3 h | 15.3 kW | 39 | 838 sq ft |
| 3.5 h | 13.1 kW | 33 | 710 sq ft |
| 4 h | 11.5 kW | 29 | 624 sq ft |
| 4.5 h | 10.2 kW | 26 | 559 sq ft |
| 5 h | 9.2 kW | 23 | 494 sq ft |
| 5.5 h | 8.3 kW | 21 | 452 sq ft |
| 6 h | 7.6 kW | 20 | 430 sq ft |
kW = monthly kWh ÷ 30 ÷ sun hours ÷ 0.8 (inverter, wiring, soiling and temperature losses). Southwest US ~5.5-6.5 h, Midwest/Northeast ~3.5-4.5 h.
FAQ
How many solar panels for 1,100 kWh a month?
About 26 panels of 400 W (10.2 kW) with 4.5 peak sun hours; 20 in a 6-hour sunny climate and 33 at 3.5 hours.
What does a 10.2 kW system cost?
At a typical $2.50-$3.20 per watt installed: $25,463-$32,593 before incentives.