Solar · guide
How many peak sun hours does my state get?
Measured as what 1 kW of panels actually makes, U.S. states get 3.0 (Alaska) to 5.3 (New Mexico) kWh per kW a day on average over the year. That’s the useful version of “peak sun hours”: it already includes the panel’s tilt and typical losses, and it changes a lot between summer and winter.
By state
kWh per kW of panels a day (Global Solar Atlas: year average, best and worst month), and NASA POWER’s flat-ground sunshine in kWh per m² a day (2001–2025), the classic “peak sun hours”.
| State | Year | Best mo. | Worst mo. | Flat sun (NASA) |
|---|---|---|---|---|
| Alabama | 4.2 | 4.8 | 3.2 | 4.6 |
| Alaska | 3.0 | 4.9 | 0.7 | 2.5 |
| Arizona | 5.2 | 5.9 | 4.4 | 5.8 |
| Arkansas | 4.2 | 4.7 | 3.2 | 4.4 |
| California | 4.9 | 5.6 | 3.8 | 5.4 |
| Colorado | 4.8 | 5.2 | 4.0 | 4.9 |
| Connecticut | 4.0 | 4.6 | 2.8 | 3.9 |
| Delaware | 4.0 | 4.6 | 2.9 | 4.1 |
| District of Columbia | 4.0 | 4.5 | 3.1 | 4.1 |
| Florida | 4.4 | 5.1 | 3.8 | 4.9 |
| Georgia | 4.2 | 4.8 | 3.3 | 4.6 |
| Hawaii | 4.6 | 5.1 | 3.8 | 5.7 |
| Idaho | 4.4 | 5.7 | 2.2 | 4.6 |
| Illinois | 3.9 | 4.8 | 2.4 | 3.9 |
| Indiana | 3.9 | 4.7 | 2.3 | 4.0 |
| Iowa | 4.0 | 4.7 | 2.5 | 4.0 |
| Kansas | 4.3 | 4.9 | 3.3 | 4.5 |
| Kentucky | 3.9 | 4.7 | 2.5 | 4.1 |
| Louisiana | 4.2 | 4.7 | 3.3 | 4.7 |
| Maine | 3.9 | 4.5 | 2.5 | 3.7 |
| Maryland | 4.0 | 4.5 | 3.0 | 4.0 |
| Massachusetts | 3.9 | 4.5 | 2.7 | 3.8 |
| Michigan | 3.7 | 4.7 | 1.8 | 3.8 |
| Minnesota | 3.9 | 4.7 | 2.3 | 3.9 |
| Mississippi | 4.2 | 4.7 | 3.2 | 4.6 |
| Missouri | 4.1 | 4.7 | 3.0 | 4.2 |
| Montana | 4.0 | 5.5 | 2.2 | 4.0 |
| Nebraska | 4.1 | 4.8 | 2.9 | 4.2 |
| Nevada | 5.3 | 5.9 | 4.2 | 5.6 |
| New Hampshire | 3.9 | 4.5 | 2.7 | 3.8 |
| New Jersey | 3.9 | 4.5 | 2.8 | 3.9 |
| New Mexico | 5.3 | 5.8 | 4.5 | 5.6 |
| New York | 4.0 | 4.6 | 2.9 | 4.0 |
| North Carolina | 4.2 | 4.8 | 3.4 | 4.4 |
| North Dakota | 4.0 | 5.0 | 2.2 | 3.9 |
| Ohio | 3.7 | 4.6 | 2.0 | 3.9 |
| Oklahoma | 4.4 | 4.9 | 3.5 | 4.7 |
| Oregon | 3.6 | 5.4 | 1.6 | 3.7 |
| Pennsylvania | 3.9 | 4.5 | 2.7 | 3.8 |
| Rhode Island | 4.0 | 4.5 | 2.9 | 4.0 |
| South Carolina | 4.3 | 5.0 | 3.5 | 4.7 |
| South Dakota | 4.1 | 5.0 | 2.8 | 4.1 |
| Tennessee | 4.0 | 4.7 | 2.9 | 4.3 |
| Texas | 4.2 | 4.7 | 3.3 | 4.7 |
| Utah | 4.5 | 5.5 | 2.7 | 4.8 |
| Vermont | 3.6 | 4.6 | 1.8 | 3.6 |
| Virginia | 4.2 | 4.7 | 3.3 | 4.3 |
| Washington | 3.5 | 5.3 | 1.4 | 3.5 |
| West Virginia | 3.7 | 4.5 | 2.2 | 3.9 |
| Wisconsin | 3.9 | 4.8 | 2.2 | 3.7 |
| Wyoming | 4.6 | 5.2 | 3.4 | 4.5 |
FAQ
How many peak sun hours does my state get?
Measured as what 1 kW of panels actually makes, U.S. states get 3.0 (Alaska) to 5.3 (New Mexico) kWh per kW a day on average over the year. That’s the useful version of “peak sun hours”: it already includes the panel’s tilt and typical losses, and it changes a lot between summer and winter.
What are peak sun hours?
The day’s sunshine expressed as hours of full sun (1,000 W per square metre). Five peak sun hours on flat ground isn’t five kWh per kW of panels: tilt adds some, and heat, wiring and inverter losses take some away. We use the Global Solar Atlas output figure, which accounts for both.
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.