How many solar panels for a 3,000 sq ft house?
About 33 panels at 400 watts (13.2 kW), assuming the 1,350 kWh a month typical of a 3,000 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 1,350 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 | 42 | 37 | 33 |
| 4.5 h (US avg) | 37 | 33 | 29 |
| 5.0 h | 33 | 29 | 26 |
| 5.5 h | 30 | 27 | 24 |
| 6.0 h | 28 | 25 | 22 |
| 6.5 h | 26 | 23 | 20 |
The same house, six real states
| State | Sun | Panels (400W) | System |
|---|---|---|---|
| Arizona | 6.5 h | 23 panels | 9.2 kW |
| Texas | 5.3 h | 28 panels | 11.2 kW |
| Florida | 5.2 h | 28 panels | 11.2 kW |
| Missouri | 4.6 h | 32 panels | 12.8 kW |
| New York | 3.9 h | 37 panels | 14.8 kW |
| Washington | 3.8 h | 38 panels | 15.2 kW |
About the 1,350 kWh assumption
Big homes where the pool, the EVs, and the wine fridge live. The honest range on usage here is 1,000 to 2,000 kWh a month depending on lifestyle, the widest of any size tier. Treat this page's figure as the midpoint and let 12 months of bills arbitrate.
Questions people ask
How many solar panels does a 3,000 sq ft house need?
About 33 400-watt panels (13.2 kW) at average US sun, assuming the 1,350 kWh a month typical of that size; 23 panels in the sunniest states, 37 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 3,000 sq ft house use?
We assume 1,350 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?
33 panels want about 693 sq ft of usable, unshaded roof once racking gaps are counted, and a 3,000 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.