Solar · system size
How much does a 20 kW solar system produce?
A 20 kW solar system makes about 29,464 kWh a year in Tennessee (the middle state for sunshine), from 21,608 in Alaska to 38,588 in New Mexico. That’s 2,455 kWh a month on average: 2,802 in June and 1,768 in December. It takes 50 × 400 W panels (67 × 300 W, or 45 × 450 W).
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A 20 kW system in every state
“Share of home” compares it with the state’s average home use (EIA 2024).
| State | kWh a year | kWh a month | Share of home |
|---|---|---|---|
| Alabama | 30,512 | 2,543 | 222% |
| Alaska | 21,608 | 1,801 | 311% |
| Arizona | 38,144 | 3,179 | 296% |
| Arkansas | 30,356 | 2,530 | 241% |
| California | 35,844 | 2,987 | 594% |
| Colorado | 34,996 | 2,916 | 433% |
| Connecticut | 29,322 | 2,444 | 352% |
| Delaware | 29,298 | 2,442 | 268% |
| District of Columbia | 29,426 | 2,452 | 384% |
| Florida | 32,308 | 2,692 | 244% |
| Georgia | 30,960 | 2,580 | 240% |
| Hawaii | 33,554 | 2,796 | 565% |
| Idaho | 32,062 | 2,672 | 283% |
| Illinois | 28,536 | 2,378 | 343% |
| Indiana | 28,158 | 2,346 | 260% |
| Iowa | 29,034 | 2,420 | 291% |
| Kansas | 31,432 | 2,619 | 299% |
| Kentucky | 28,514 | 2,376 | 227% |
| Louisiana | 30,990 | 2,582 | 215% |
| Maine | 28,416 | 2,368 | 430% |
| Maryland | 29,138 | 2,428 | 261% |
| Massachusetts | 28,656 | 2,388 | 419% |
| Michigan | 26,932 | 2,244 | 363% |
| Minnesota | 28,344 | 2,362 | 332% |
| Mississippi | 30,938 | 2,578 | 223% |
| Missouri | 30,086 | 2,507 | 251% |
| Montana | 29,502 | 2,458 | 288% |
| Nebraska | 30,274 | 2,523 | 264% |
| Nevada | 38,438 | 3,203 | 345% |
| New Hampshire | 28,514 | 2,376 | 384% |
| New Jersey | 28,790 | 2,399 | 362% |
| New Mexico | 38,588 | 3,216 | 492% |
| New York | 29,280 | 2,440 | 427% |
| North Carolina | 30,858 | 2,572 | 253% |
| North Dakota | 29,138 | 2,428 | 236% |
| Ohio | 27,066 | 2,256 | 267% |
| Oklahoma | 32,164 | 2,680 | 248% |
| Oregon | 26,082 | 2,174 | 246% |
| Pennsylvania | 28,386 | 2,366 | 289% |
| Rhode Island | 29,056 | 2,421 | 427% |
| South Carolina | 31,320 | 2,610 | 248% |
| South Dakota | 30,186 | 2,516 | 253% |
| Tennessee | 29,464 | 2,455 | 213% |
| Texas | 30,466 | 2,539 | 232% |
| Utah | 32,648 | 2,721 | 351% |
| Vermont | 26,156 | 2,180 | 380% |
| Virginia | 30,344 | 2,529 | 245% |
| Washington | 25,850 | 2,154 | 225% |
| West Virginia | 26,990 | 2,249 | 219% |
| Wisconsin | 28,344 | 2,362 | 366% |
| Wyoming | 33,274 | 2,773 | 321% |
FAQ
How much does a 20 kW solar system produce?
A 20 kW solar system makes about 29,464 kWh a year in Tennessee (the middle state for sunshine), from 21,608 in Alaska to 38,588 in New Mexico. That’s 2,455 kWh a month on average: 2,802 in June and 1,768 in December. It takes 50 × 400 W panels (67 × 300 W, or 45 × 450 W).
How many solar panels are in a 20 kW system?
50 × 400 W panels, 67 × 300 W or 45 × 450 W (panel count = 20,000 W ÷ panel watts, rounded up).
Is a 20 kW system enough for my home?
In Tennessee it makes about 213% of the average home’s use there (1,154 kWh a month, EIA 2024). Compare it with the kWh on your own bills; the state table shows every state.
Sources and assumptions
- Solar output (kWh per kW of panels, by month): Global Solar Atlas 2.0, long-term averages to 2025 (data version 2.2.68, updated 2026-04-01), for crystalline-silicon panels facing south at the best fixed tilt, after typical system losses. Data obtained from the “Global Solar Atlas 2.0, a free, web-based application is developed and operated by the company Solargis s.r.o. on behalf of the World Bank Group, utilizing Solargis data, with funding provided by the Energy Sector Management Assistance Program (ESMAP). For additional information: https://globalsolaratlas.info” Licensed CC BY 4.0; we rounded and combined it as described here. Not affiliated with or endorsed by Solargis or the World Bank Group.
- State figure: population-weighted average of the state’s three largest cities (U.S. Census Bureau Vintage 2024 population estimates; coordinates from the 2020 Census Gazetteer). Hawaii and DC use one city.
- Cross-check: NASA POWER sunshine climatology (2001–2025), tilted with a standard isotropic-sky model × 0.80. States more than 12% apart were reviewed by hand; the gaps are explained on our methodology page.
- Home use: EIA Table 5A, 2024 average monthly residential kWh by state. Rates: EIA Electric Power Monthly, August 2026.
- Tax credit: IRS FAQ on the One, Big, Beautiful Bill (FS-2025-05, Aug. 21, 2025).
- Assumptions: 85% charging efficiency into a battery, 85% from battery to appliance, panel counts rounded up, off-grid sizing for the worst month.