10 kW solar system: cost, output and payback
A 10 kW solar system is 25 panels and costs about $28,500 installed, or $19,950 after the US federal tax credit. Across 673 measured cities it produces a median of 13,141 kWh a year and pays back in about 11.4 years.
Check whether 25 panels fit your actual roof → These are medians across real cities; your roof's size, pitch and shading change the answer.
Is a 10 kW system the right size?
This is more than most households need. A 10 kW array covers roughly 122% of an average home's 10,800 kWh a year, so unless you have electric heating, an EV, a pool or unusually high usage, you would be exporting a large share of it — usually at well below the retail rate you paid to install the panels.
What a 10 kW system produces where you live
Output depends almost entirely on local sunlight. The same 10 kW of hardware produces 17,978 kWh a year in Palmdale and 8,109 kWh in Fairbanks — a 2.2× spread across 673 cities we have measured from Google's rooftop imagery.
Where a 10 kW system pays back fastest
Payback is driven more by electricity price than by sunshine. Honolulu, HI tops the list at 4 years on 42.1¢/kWh, while Gatineau, QC takes 33.3 years on just 7.9¢/kWh. That is identical hardware producing 28% less electricity, but taking 8.3× as long to pay for itself — because the power it displaces is worth 5.3× less.
| City | kWh/yr | Rate | Payback |
|---|---|---|---|
| Honolulu, HI | 15,190 | 42.1¢ | 4 yrs |
| Lihue, HI | 15,105 | 42.1¢ | 4 yrs |
| Kahului, HI | 13,830 | 42.1¢ | 4.1 yrs |
| Hilo, HI | 12,835 | 42.1¢ | 4.2 yrs |
| Kailua-Kona, HI | 10,651 | 42.1¢ | 4.4 yrs |
| Quincy, MA | 12,929 | 30.1¢ | 5.8 yrs |
| Boston, MA | 12,291 | 30.1¢ | 5.9 yrs |
| Worcester, MA | 12,266 | 30.1¢ | 5.9 yrs |
| Fall River, MA | 12,147 | 30.1¢ | 6 yrs |
| Lowell, MA | 12,087 | 30.1¢ | 6 yrs |
| Somerville, MA | 12,053 | 30.1¢ | 6 yrs |
| Cambridge, MA | 11,934 | 30.1¢ | 6 yrs |
| Lynn, MA | 11,832 | 30.1¢ | 6 yrs |
| Newton, MA | 11,688 | 30.1¢ | 6 yrs |
| Greenfield, MA | 11,654 | 30.1¢ | 6 yrs |
Where it pays back slowest
| City | kWh/yr | Rate | Payback |
|---|---|---|---|
| Gatineau, QC | 10,974 | 7.9¢ | 33.3 yrs |
| Levis, QC | 11,271 | 7.9¢ | 33 yrs |
| Trois-Rivières, QC | 11,450 | 7.9¢ | 32.9 yrs |
| Longueuil, QC | 11,620 | 7.9¢ | 32.8 yrs |
| Drummondville, QC | 11,654 | 7.9¢ | 32.8 yrs |
| Terrebonne, QC | 11,730 | 7.9¢ | 32.7 yrs |
| Montreal, QC | 11,764 | 7.9¢ | 32.7 yrs |
| Laval, QC | 11,773 | 7.9¢ | 32.7 yrs |
| Quebec City, QC | 11,968 | 7.9¢ | 32.5 yrs |
| Winnipeg, MB | 11,807 | 10.1¢ | 25.5 yrs |
Other system sizes
10 kW solar questions
How many panels is a 10 kW solar system?
A 10 kW system is 25 panels at 400W each, the standard residential size in 2026. It needs roughly 50 m² (about 538 sq ft) of usable roof, and more in practice once you allow for edge setbacks, vents and access paths.
How much does a 10 kW solar system cost?
About $28,500 installed before incentives at $2.85 per watt, or roughly $19,950 after the 30% US federal tax credit. Quotes for the same 10 kW system routinely differ by thousands, because labour, margin and equipment vary far more than hardware cost does.
How much power does a 10 kW solar system produce?
Across the 673 cities we have measured, a 10 kW array produces a median of 13,141 kWh a year. The range runs from about 8,109 kWh in Fairbanks to 17,978 kWh in Palmdale — the same hardware, differing by 122% purely on local sunlight.
See the full dataset → every city, with sunlight, shading, roof size and rates.
Estimates generated 2026-08-22 from Google Solar API rooftop samples across 673 cities. Not a quote and not financial advice.