Calculator › San Francisco, California
Solar panels in San Francisco, California
San Francisco receives 4.89 peak sun hours a day and 1,783 kWh/m² of solar energy a year. That is measured satellite data for San Francisco's coordinates, not a national average — and it changes the panel count.
San Francisco solar data
4.89peak sun hours/day
1,783annual irradiance (kWh/m²)
1.61kWh/day from one 400 W panel
589kWh/year from one 400 W panel
Monthly solar irradiance in San Francisco
| Month | Peak sun hours/day | Share of year |
|---|---|---|
| January | 2.17 | 0.2 |
| February | 3.05 | 0.3 |
| March | 4.61 | 0.4 |
| April | 6.18 | 0.5 |
| May | 7.22 | 0.6 |
| June | 7.53 | 0.6 |
| July | 6.94 | 0.6 |
| August | 6.32 | 0.5 |
| September | 5.07 | 0.4 |
| October | 4.37 | 0.4 |
| November | 2.80 | 0.2 |
| December | 2.16 | 0.2 |
Source: NASA POWER daily point API, parameter ALLSKY_SFC_SW_DWN (global horizontal irradiance), year 2024. Coordinates 37.7749, -122.4194.
How many solar panels does San Francisco need?
For a typical US household using 900 kWh a month, San Francisco needs about 19 panels of 400 W (7.43 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.