Solar panels needed for 1,500 kWh per month
35 panels
of 400 W (13.9 kW) cover 1,500 kWh/month at 4.5 peak sun hours · about $38,889 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 | 20.8 kW | 53 | 1,140 sq ft |
| 3.5 h | 17.9 kW | 45 | 968 sq ft |
| 4 h | 15.6 kW | 40 | 860 sq ft |
| 4.5 h | 13.9 kW | 35 | 752 sq ft |
| 5 h | 12.5 kW | 32 | 688 sq ft |
| 5.5 h | 11.4 kW | 29 | 624 sq ft |
| 6 h | 10.4 kW | 27 | 580 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 1,500 kWh a month?
About 35 panels of 400 W (13.9 kW) with 4.5 peak sun hours; 27 in a 6-hour sunny climate and 45 at 3.5 hours.
What does a 13.9 kW system cost?
At a typical $2.50-$3.20 per watt installed: $34,722-$44,444 before incentives.