How Many Solar Panels for 1,500 kWh per Month?
To cover 1,500 kWh per month you need about 13.7 kW of solar, or 35 panels of 400 W, assuming 4.5 peak sun hours a day. Depending on where you live that ranges from 26 panels (Southwest) to 45 panels (Northeast). The array needs roughly 735 sq ft of roof.
Solar panels for 1,500 kWh by region
| Region | Sun hours | System size | 400 W panels | Roof space |
|---|---|---|---|---|
| Northeast / Pacific Northwest | 3.5 | 17.61 kW | 45 | 945 sq ft |
| Midwest / Mid-Atlantic | 4.5 | 13.7 kW | 35 | 735 sq ft |
| Southeast / Texas | 5 | 12.33 kW | 31 | 651 sq ft |
| Southwest | 6 | 10.27 kW | 26 | 546 sq ft |
Based on 100% offset, 400 W panels and about 21 sq ft per panel. Peak sun hours are regional averages.
Cost of a 13.7 kW system
| Region | System size | At $2.50/W | At $3.00/W | At $3.50/W |
|---|---|---|---|---|
| Northeast / Pacific Northwest | 17.61 kW | $44,031 | $52,838 | $61,644 |
| Midwest / Mid-Atlantic | 13.7 kW | $34,247 | $41,096 | $47,945 |
| Southeast / Texas | 12.33 kW | $30,822 | $36,986 | $43,151 |
| Southwest | 10.27 kW | $25,685 | $30,822 | $35,959 |
Installed cost before any rebates. Cost is system watts × price per watt. The federal 25D credit ended for systems installed after December 31, 2025.
How it is calculated (4.5 sun hours)
1,500 kWh × 12 = 18,000 kWh per year (49.3 kWh per day)
18,000 ÷ (4.5 × 365 × 0.8) = 13.7 kW
13,699 W ÷ 400 W = 34.25 → 35 panels
35 × 21 sq ft = 735 sq ft of roof
Tips at 1,500 kWh per month
- Check your roof space – 35 panels need about 735 sq ft of usable, unshaded roof. Many roofs cannot fit this on one side, so a split east/west layout or a ground mount may be needed.
- Look for the big loads – Usage this high often comes from electric heating, a pool pump, an EV or central air. Check those before sizing – a heat pump water heater or EV charge timing can shrink the system.
- Batteries – Batteries are sized separately from panels. At this usage, backing up the whole home is expensive; most owners back up essential circuits with one or two batteries.
Frequently asked questions
How many solar panels do I need for 1,500 kWh per month?
About 35 panels of 400 W (13.7 kW) in a region with 4.5 peak sun hours. That ranges from 26 panels in the Southwest to 45 in the Northeast and Pacific Northwest.
How big a solar system do I need for 1,500 kWh a month?
1,500 kWh a month is 18,000 kWh a year. Divided by 4.5 sun hours × 365 days × 0.8 system efficiency, that gives a 13.7 kW system. It is 10.27 kW with 6.0 sun hours and 17.61 kW with 3.5.
How much does solar cost for 1,500 kWh per month?
At 4.5 sun hours the system costs about $34,247 to $47,945 installed ($2.50–$3.50 per watt), or $41,096 at $3.00. The federal 25D credit ended for systems installed after December 31, 2025, so check state and utility rebates separately.