Data is from the NREL.gov app for average solar radiation energy per day in Des Moines, Iowa. We used this reference point to compute the solar radiation energy production per day (in kWh/m²), which changes throughout the year according to the month. Each month is different due to the changing relative trajectory of the sun.
To get the monthly production, we simply multiplied by the number of days for each month. Finally to get the annual production, we added up all of the monthly values.
The average solar panel surface area is estimated to be 1.5 square meters. The efficiency of converting solar radiation into energy is estimated to be 15%.
| Month | Solar radiation per day | Solar radiation per month | Solar energy per month 1 panel | Solar energy per month 20 panels |
| January | 2.94 kWh/m² | 91.14 kWh/m² | 20.51 kWh | 410.13 kWh |
| February | 3.76 kWh/m² | 116.56 kWh/m² | 26.23 kWh | 524.52 kWh |
| March | 4.49 kWh/m² | 139.19 kWh/m² | 31.32 kWh | 626.36 kWh |
| April | 5.48 kWh/m² | 169.88 kWh/m² | 38.22 kWh | 764.46 kWh |
| May | 5.98 kWh/m² | 185.38 kWh/m² | 41.71 kWh | 834.21 kWh |
| June | 6.41 kWh/m² | 198.71 kWh/m² | 44.71 kWh | 894.20 kWh |
| July | 6.49 kWh/m² | 201.19 kWh/m² | 45.27 kWh | 905.36 kWh |
| August | 6.11 kWh/m² | 189.41 kWh/m² | 42.62 kWh | 852.35 kWh |
| September | 5.81 kWh/m² | 180.11 kWh/m² | 40.52 kWh | 810.50 kWh |
| October | 4.33 kWh/m² | 134.23 kWh/m² | 30.20 kWh | 604.04 kWh |
| November | 3.09 kWh/m² | 95.79 kWh/m² | 21.55 kWh | 431.06 kWh |
| December | 2.54 kWh/m² | 78.74 kWh/m² | 17.72 kWh | 354.33 kWh |
Anne Lauer
Anna Lauer is a writer, gardener, and homesteader living in rural Wisconsin. She has written for Mother Earth News, Grit, and Hobby Farms magazines. Anna is writing a new book about growing your food for free and an ultimate guide to producing food at little to no cost. When she’s not writing or gardening, Anna enjoys spending time with her husband and two young daughters.