Solar panels needed for 700 kWh per month
17 panels
of 400 W (6.5 kW) cover 700 kWh/month at 4.5 peak sun hours · about $18,148 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 | 9.7 kW | 25 | 538 sq ft |
| 3.5 h | 8.3 kW | 21 | 452 sq ft |
| 4 h | 7.3 kW | 19 | 408 sq ft |
| 4.5 h | 6.5 kW | 17 | 366 sq ft |
| 5 h | 5.8 kW | 15 | 322 sq ft |
| 5.5 h | 5.3 kW | 14 | 301 sq ft |
| 6 h | 4.9 kW | 13 | 280 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 700 kWh a month?
About 17 panels of 400 W (6.5 kW) with 4.5 peak sun hours; 13 in a 6-hour sunny climate and 21 at 3.5 hours.
What does a 6.5 kW system cost?
At a typical $2.50-$3.20 per watt installed: $16,204-$20,741 before incentives.