How many solar panels for a 1,500 sq ft house?
About 19 panels at 400 watts (7.6 kW), assuming the 800 kWh a month typical of a 1,500 sq ft home and average US sun. But hear the assumption creak: houses don't use electricity, habits do. If you have actual bills, feed those to the calculator and skip the proxy; if you're sizing a house you haven't moved into yet, this page is the right tool.
Panel count by sun and wattage
At the assumed 800 kWh a month, rounded up, 0.77 derate applied. Bold is the US-average column.
| Peak sun hours | 350W panels | 400W panels | 450W panels |
|---|---|---|---|
| 4.0 h | 25 | 22 | 19 |
| 4.5 h (US avg) | 22 | 19 | 17 |
| 5.0 h | 20 | 18 | 16 |
| 5.5 h | 18 | 16 | 14 |
| 6.0 h | 17 | 15 | 13 |
| 6.5 h | 16 | 14 | 12 |
The same house, six real states
| State | Sun | Panels (400W) | System |
|---|---|---|---|
| Arizona | 6.5 h | 14 panels | 5.6 kW |
| Texas | 5.3 h | 17 panels | 6.8 kW |
| Florida | 5.2 h | 17 panels | 6.8 kW |
| Missouri | 4.6 h | 19 panels | 7.6 kW |
| New York | 3.9 h | 22 panels | 8.8 kW |
| Washington | 3.8 h | 23 panels | 9.2 kW |
About the 800 kWh assumption
The classic three-bed ranch. Answers around 16 panels get quoted a lot for this size (solar.com's example lands there too, at 6.6 kW); our count is the same math with the sun figure made explicit, which is where quotes and reality usually part ways.
Questions people ask
How many solar panels does a 1,500 sq ft house need?
About 19 400-watt panels (7.6 kW) at average US sun, assuming the 800 kWh a month typical of that size; 14 panels in the sunniest states, 22 in the cloudiest. If you have 12 months of bills, use those instead: square feet are a proxy, kWh are the truth.
How much electricity does a 1,500 sq ft house use?
We assume 800 kWh a month, scaled from EIA's ~900 kWh national household average with usage growing slower than floor area. Heating fuel is the big swing: this figure fits gas heat, and all-electric resistance heat can add 50% or more in winter climates.
Will the panels fit on the roof?
19 panels want about 399 sq ft of usable, unshaded roof once racking gaps are counted, and a 1,500 sq ft single-story home has roughly its footprint in gross roof, less pitch effects, vents, setbacks, and the north face. Usually yes on a simple gable, tight on complex roofs. Two-story homes have half the footprint to work with.