Peak sun hours by state, all 50 ranked
The spread runs from 6.5 hours a day in Arizona to 3.0 in Alaska, and it decides panel counts before you pick a single product: the same 900 kWh bill needs 15 panels in Arizona sun and 33 in Alaska's. Find your state, note the hours, then let the calculator turn it into your count.
| # | State | Peak sun hours/day | Sun meter | Panels for 900 kWh/mo |
|---|---|---|---|---|
| 1 | Arizona | 6.5 | desert-grade sun | 15 |
| 2 | New Mexico | 6.4 | desert-grade sun | 16 |
| 3 | Nevada | 6.2 | desert-grade sun | 16 |
| 4 | California | 5.8 | strong sun | 17 |
| 5 | Hawaii | 5.6 | strong sun | 18 |
| 6 | Colorado | 5.5 | strong sun | 18 |
| 7 | Utah | 5.5 | strong sun | 18 |
| 8 | Texas | 5.3 | strong sun | 19 |
| 9 | Florida | 5.2 | strong sun | 19 |
| 10 | Kansas | 5.2 | strong sun | 19 |
| 11 | Oklahoma | 5.1 | solid mid-pack sun | 19 |
| 12 | Wyoming | 5.0 | solid mid-pack sun | 20 |
| 13 | Georgia | 4.9 | solid mid-pack sun | 20 |
| 14 | Louisiana | 4.9 | solid mid-pack sun | 20 |
| 15 | Nebraska | 4.8 | solid mid-pack sun | 21 |
| 16 | South Carolina | 4.8 | solid mid-pack sun | 21 |
| 17 | Arkansas | 4.7 | solid mid-pack sun | 21 |
| 18 | Mississippi | 4.7 | solid mid-pack sun | 21 |
| 19 | North Carolina | 4.7 | solid mid-pack sun | 21 |
| 20 | Alabama | 4.6 | solid mid-pack sun | 21 |
| 21 | Idaho | 4.6 | solid mid-pack sun | 21 |
| 22 | Missouri | 4.6 | solid mid-pack sun | 21 |
| 23 | South Dakota | 4.6 | solid mid-pack sun | 21 |
| 24 | Iowa | 4.4 | solid mid-pack sun | 22 |
| 25 | Tennessee | 4.4 | solid mid-pack sun | 22 |
| 26 | Virginia | 4.4 | solid mid-pack sun | 22 |
| 27 | Kentucky | 4.3 | modest sun | 23 |
| 28 | Montana | 4.3 | modest sun | 23 |
| 29 | North Dakota | 4.3 | modest sun | 23 |
| 30 | Delaware | 4.2 | modest sun | 23 |
| 31 | Illinois | 4.2 | modest sun | 23 |
| 32 | Indiana | 4.2 | modest sun | 23 |
| 33 | Maryland | 4.2 | modest sun | 23 |
| 34 | Minnesota | 4.2 | modest sun | 23 |
| 35 | New Jersey | 4.1 | modest sun | 24 |
| 36 | Rhode Island | 4.1 | modest sun | 24 |
| 37 | Connecticut | 4.0 | modest sun | 25 |
| 38 | Massachusetts | 4.0 | modest sun | 25 |
| 39 | Oregon | 4.0 | modest sun | 25 |
| 40 | Wisconsin | 4.0 | modest sun | 25 |
| 41 | Maine | 3.9 | modest sun | 25 |
| 42 | New Hampshire | 3.9 | modest sun | 25 |
| 43 | New York | 3.9 | modest sun | 25 |
| 44 | Ohio | 3.9 | modest sun | 25 |
| 45 | Pennsylvania | 3.9 | modest sun | 25 |
| 46 | West Virginia | 3.9 | modest sun | 25 |
| 47 | Michigan | 3.8 | cloudy-country sun | 26 |
| 48 | Vermont | 3.8 | cloudy-country sun | 26 |
| 49 | Washington | 3.8 | cloudy-country sun | 26 |
| 50 | Alaska | 3.0 | cloudy-country sun | 33 |
Figures are statewide annual averages compiled from NREL solar resource data, rounded to 0.1; panel counts assume 400W panels and the 0.77 output derate documented on the methodology page. A statewide average is a starting point, not a site survey. Big states hide a lot of weather, and each state page below says which way the spread runs.
Reading the number
Every 0.5 hours of sun is roughly a 10% change in what each panel produces over a year. That compounds into real money at quote time: a system bid for Denver sun (5.5) delivers about 30% less energy if your roof actually lives under Cleveland sun (3.9-ish). When a quote's production estimate implies more sun than your state's figure, ask the installer what irradiance data they used. The good ones answer with a PVWatts report for your address.
Questions people ask
What is a peak sun hour?
One peak sun hour is one hour of sunlight at full standard strength: 1,000 watts per square meter, or 1 kWh per square meter of energy. A real day delivers weaker sun over more hours; the peak-sun-hours figure compresses the whole day into equivalent full-strength hours so panel math stays simple. Six hazy hours plus a strong midday might total 4.5 peak sun hours.
Which state has the most peak sun hours?
Arizona, at about 6.5 hours a day averaged over the year, with New Mexico (6.4) and Nevada (6.2) right behind. The cloudiest are Alaska at about 3.0 and the Pacific Northwest and Great Lakes states at 3.6 to 4.0. The full ranking is in the table above.
How many peak sun hours do I get at my address?
Start with your state’s figure above, then run your street address through NREL’s free PVWatts tool for the local number; it uses decades of measured weather for your grid cell. Statewide averages hide real spread. Eastern Washington gets about 1.5 more hours a day than Seattle, and West Texas beats Houston by a similar margin.
Are peak sun hours the same as daylight hours?
No. A June day in Seattle has 16 hours of daylight but about 5 peak sun hours once cloud and sun angle are counted; a December day there has 8.5 daylight hours and barely 1 peak sun hour. Daylight is when you can see; peak sun hours are when panels earn.