Solar Insolation

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Solar Insolation

This chart shows solar insolation in kilowatt-hours per square meter per day in many US locations. For simplicity, we call this figure "Sun Hours/Day."   This is mathematically correct because the noon sun falling on one square meter is about 1 kilowatt.

To find avarage sun hours per day in your area (line 3), check local weather data, look at the map on the previous page or find a city In the table below that has similar weather to your location.

If you want year-round autonomy, use the lowest of the two figures. If you want only 100% autonomy in summer, use the higher figure.

 

StateCity               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  Tuscan              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  Pheonix             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   Bismark            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   Binghampton        3.93  1.62  3.16
 CO  Grandby             7.47  5.15  5.69       NY   Ithica             4.57  2.29  3.79
 CO  Grand Lake          5.86  3.56  5.08       NY   Schenetady         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
 DC  Washington          4.69  3.37  4.23       OH   Columbus           5.26  2.66  4.15
 FL  Aplachicola         5.98  4.92  5.49       OH   Cleveland          4.79  2.69  3.94
 FL  Belie Is.           5.31  4.58  4.99       OK   Stillwater         5.52  4.22  4.99
 FL  Miami               6.26  5.05  5.62       OK   Oklahoma City      6.26  4.98  5.59
 FL  Gainsville          5.81  4.71  5.27       OR   Astoria            4.76  1.99  3.72
 FL  Tampa               6.16  5.26  5.67       OR   Corvallis          5.71  1.90  4.03
 GA  Atlanta             5.16  4.09  4.74       OR   Medford            5.84  2.02  4.51
 GA  Griffin             5.41  4.26  4.99       PA   Pittsburg          4.19  1.45  3.28
 HI  Honolulu            6.71  5.59  6.02       PA   State College      4.44  2.79  3.91
 IA  Ames                4.80  3.73  4.40       RI   Newport            4.69  3.58  4.23
 ID  Boise               5.83  3.33  4.92       SC   Charleston         5.72  4.23  5.06
 ID  Twin Falls          5.42  3.42  4.70       SD   Rapid City         5.91  4.56  5.23
 IL  Chicago             4.08  1.47  3.14       TN   Nashville          5.20  3.14  4.45
 IN  Indianapolis        5.02  2.55  4.21       TN   Oak Ridge          5.06  3.22  4.37
 KS  Manhattan           5.08  3.62  4.57       TX;  San Antonio        5.88  4.65  5.30
 KS  Dodge City          6.50  4.20  5.60       TX   Brownsville        5.49  4.42  4.92
 KY  Lexington           5.97  3.60  4.94       TX   El Paso            7.42  5.87  6.72
 LA  Lake Charles        5.73  4.29  4.93       TX   Midland            6.33  5.23  5.83
 LA  New Orleans         5.71  3.63  4.92       TX   Fort Worth         6.00  4.80  5.43
 LA  Shreveport          4.99  3.87  4.63       UT   Salt Lake City     6.09  3.78  5.26
 MA  E. Wareham          4.48  3.06  3.99       UT   Flaming Gorge      6.63  5.48  5.83
 MA  Boston              4.27  2.99  3.84       VA   Richmond           4.50  3.37  4.13
 MA  Blue Hill           4.38  3.33  4.05       WA   Seattle            4.83  1.60  3.57
 MA  Natick              4.62  3.09  4.10       WA   Richland           6.13  2.01  4.44
 MA  Lynn                4.60  2.33  3.79       WA   Pullman            6.07  2.90  4.73
 MD  Silver Hill         4.71  3.84  4.47       WA   Spokane            5.53  1.16  4.48
 ME  Caribou             5.62  2.57  4.19       WA   Prosser            6.21  3.06  5.03
 ME  Portland            5.23  3.56  4.51       WI   Madison            4.85  3.28  4.29
 Ml  Sault Ste. Marie    4.83  2.33  4.20       WV   Charleston         4.12  2.47  3.65
 Ml  E. Lansing          4.71  2.70  4.00       WY   Lander             6.81  5.50  6.06
 MN  St. Cloud           5.43  3.53  4.53