Calculator › St Louis, Missouri
Solar panels in St Louis, Missouri
St Louis receives 4.33 peak sun hours a day and 1,581 kWh/m² of solar energy a year. That is measured satellite data for St Louis's coordinates, not a national average — and it changes the panel count.
St Louis solar data
4.33peak sun hours/day
1,581annual irradiance (kWh/m²)
1.43kWh/day from one 400 W panel
522kWh/year from one 400 W panel
Monthly solar irradiance in St Louis
| Month | Peak sun hours/day | Share of year |
|---|---|---|
| January | 1.77 | 0.1 |
| February | 3.50 | 0.3 |
| March | 4.54 | 0.4 |
| April | 5.12 | 0.4 |
| May | 5.85 | 0.5 |
| June | 6.86 | 0.6 |
| July | 5.77 | 0.5 |
| August | 5.54 | 0.5 |
| September | 4.53 | 0.4 |
| October | 4.31 | 0.4 |
| November | 2.27 | 0.2 |
| December | 1.79 | 0.1 |
Source: NASA POWER daily point API, parameter ALLSKY_SFC_SW_DWN (global horizontal irradiance), year 2024. Coordinates 38.627, -90.1994.
How many solar panels does St Louis need?
For a typical US household using 900 kWh a month, St Louis needs about 21 panels of 400 W (8.39 kWp), with a south-facing roof. That is fewer panels than the same household would need in a city with 4.5 peak sun hours.