Solar insolation data for several cities across the USA.
Find the city closest to you and select the low value for your calculation (the worst case value) for off-grid systems.
| State | City | High | Low | Avg | State | City | High | Low | Avg | |
| AK | Fairbanks | 5.87 | 2.12 | 3.99 | MO | Columbia | 5.50 | 3.97 | 4.73 | |
| AK | Matanuska | 5.24 | 1.74 | 3.55 | MO | St. Louis | 4.87 | 3.24 | 4.38 | |
| AL | Montgomery | 4.69 | 3.37 | 4.23 | MS | Meridian | 4.86 | 3.64 | 4.43 | |
| AR | Bethel | 6.29 | 2.37 | 3.81 | MT | Glasgow | 5.97 | 4.09 | 5.15 | |
| AR | Little Rock | 5.29 | 3.88 | 4.69 | MT | Great Falls | 5.70 | 3.66 | 4.93 | |
| AZ | Tucson | 7.42 | 6.01 | 6.57 | MT | Summit | 5.17 | 2.36 | 3.99 | |
| AZ | Page | 7.30 | 5.65 | 6.36 | NM | Albuquerque | 7.16 | 6.21 | 6.77 | |
| AZ | Phoenix | 7.13 | 5.78 | 6.58 | NB | Lincoln | 5.40 | 4.38 | 4.79 | |
| CA | Santa Maria | 6.52 | 5.42 | 5.94 | NB | N. Omaha | 5.28 | 4.26 | 4.90 | |
| CA | Riverside | 6.35 | 5.35 | 5.87 | NC | Cape Hatteras | 5.81 | 4.69 | 5.31 | |
| CA | Davis | 6.09 | 3.31 | 5.10 | NC | Greensboro | 5.05 | 4.00 | 4.71 | |
| CA | Fresno | 6.19 | 3.42 | 5.38 | ND | Bismarck | 5.48 | 3.97 | 5.01 | |
| CA | Los Angeles | 6.14 | 5.03 | 5.62 | NJ | Sea Brook | 4.76 | 3.20 | 4.21 | |
| CA | Soda Springs | 6.47 | 4.40 | 5.60 | NV | Las Vegas | 7.13 | 5.84 | 6.41 | |
| CA | La Jolla | 5.24 | 4.29 | 4.77 | NV | Ely | 6.48 | 5.49 | 5.98 | |
| CA | Inyokern | 8.70 | 6.87 | 7.66 | NY | Binghamton | 3.93 | 1.62 | 3.16 | |
| CO | Grandby | 7.47 | 5.15 | 5.69 | NY | Ithaca | 4.57 | 2.29 | 3.79 | |
| CO | Grand Lake | 5.86 | 3.56 | 5.08 | NY | Schenectady | 3.92 | 2.53 | 3.55 | |
| CO | Grand Junction | 6.34 | 5.23 | 5.85 | NY | Rochester | 4.22 | 1.58 | 3.31 | |
| CO | Boulder | 5.72 | 4.44 | 4.87 | NY | New York City | 4.97 | 3.03 | 4.08 | |
| CT | Hartford | 5.40 | 3.33 | 4.74 | OH | Columbus | 5.26 | 2.66 | 4.15 | |
| DC | Washington | 4.69 | 3.37 | 4.23 | OH | Cleveland | 4.79 | 2.69 | 3.94 | |
| FL | Appalachicola | 5.98 | 4.92 | 5.49 | OK | Stillwater | 5.52 | 4.22 | 4.99 | |
| FL | Belie Is. | 5.31 | 4.58 | 4.99 | OK | Oklahoma City | 6.26 | 4.98 | 5.59 | |
| FL | Miami | 6.26 | 5.05 | 5.62 | OR | Astoria | 4.76 | 1.99 | 3.72 | |
| FL | Gainesville | 5.81 | 4.71 | 5.27 | OR | Corvallis | 5.71 | 1.90 | 4.03 | |
| FL | Tampa | 6.16 | 5.26 | 5.67 | OR | Medford | 5.84 | 2.02 | 4.51 | |
| GA | Atlanta | 5.16 | 4.09 | 4.74 | PA | Pittsburgh | 4.19 | 1.45 | 3.28 | |
| GA | Griffin | 5.41 | 4.26 | 4.99 | PA | State College | 4.44 | 2.79 | 3.91 | |
| HI | Honolulu | 6.71 | 5.59 | 6.02 | RI | Newport | 4.69 | 3.58 | 4.23 | |
| IA | Ames | 4.80 | 3.73 | 4.40 | SC | Charleston | 5.72 | 4.23 | 5.06 | |
| ID | Boise | 5.83 | 3.33 | 4.92 | SD | Rapid City | 5.91 | 4.56 | 5.23 | |
| ID | Twin Falls | 5.42 | 3.42 | 4.70 | TN | Nashville | 5.20 | 3.14 | 4.45 | |
| IL | Chicago | 4.08 | 1.47 | 3.14 | TN | Oak Ridge | 5.06 | 3.22 | 4.37 | |
| IN | Indianapolis | 5.02 | 2.55 | 4.21 | TX | San Antonio | 5.88 | 4.65 | 5.30 | |
| KN | Manhattan | 5.08 | 3.62 | 4.57 | TX | Brownsville | 5.49 | 4.42 | 4.92 | |
| KN | Dodge City | 4.14 | 5.28 | 5.79 | TX | El Paso | 7.42 | 5.87 | 6.72 | |
| KY | Lexington | 5.97 | 3.60 | 4.94 | TX | Midland | 6.33 | 5.23 | 5.83 | |
| LA | Lake Charles | 5.73 | 4.29 | 4.93 | TX | Fort Worth | 6.00 | 4.80 | 5.43 | |
| LA | New Orleans | 5.71 | 3.63 | 4.92 | UT | Salt Lake City | 6.09 | 3.78 | 5.26 | |
| LA | Shreveport | 4.99 | 3.87 | 4.63 | UT | Flaming Gorge | 6.63 | 5.48 | 5.83 | |
| MA | E. Wareham | 4.48 | 3.06 | 3.99 | VA | Richmond | 4.50 | 3.37 | 4.13 | |
| MA | Boston | 4.27 | 2.99 | 3.84 | WA | Seattle | 4.83 | 1.60 | 3.57 | |
| MA | Blue Hill | 4.38 | 3.33 | 4.05 | WA | Richland | 6.13 | 2.01 | 4.44 | |
| MA | Natick | 4.62 | 3.09 | 4.10 | WA | Pullman | 6.07 | 2.90 | 4.73 | |
| MA | Lynn | 4.60 | 2.33 | 3.79 | WA | Spokane | 5.53 | 1.16 | 4.48 | |
| MD | Silver Hill | 4.71 | 3.84 | 4.47 | WA | Prosser | 6.21 | 3.06 | 5.03 | |
| ME | Caribou | 5.62 | 2.57 | 4.19 | WI | Madison | 4.85 | 3.28 | 4.29 | |
| ME | Portland | 5.23 | 3.56 | 4.51 | WV | Charleston | 4.12 | 2.47 | 3.65 | |
| MI | Saulte Ste. Marie | 4.83 | 2.33 | 4.20 | WY | Lander | 6.81 | 5.50 | 6.06 | |
| MI | E. Lansing | 4.71 | 2.70 | 4.00 | ||||||
| MN | St. Cloud | 5.43 | 3.53 | 4.53 |
Source: National Renewable Energy Laboratory
