Peak sun hours in California
California averages 5.8 peak sun hours a day across the year, 4th of the 50 states. At that figure a 400-watt panel produces about 1.79 kWh a day after real-world losses, and covering the 900 kWh average US bill takes about 17 panels. Los Angeles, the state's biggest city, trails the statewide figure at 5.6 hours, so the rest of the state leans the other way; treat 5.8 as the midpoint of a real spread.
strong sun: 5.8 of a possible ~6.5 hours
Panel counts for California bills
Computed at California's 5.8 hours with 400W panels and the 0.77 derate; the US-average column shows what the same bill takes at 4.5 hours, so you can see what your state's sun is worth in hardware.
| Monthly usage | California | System size | US average |
|---|---|---|---|
| 500 kWh/mo | 10 panels | 4 kW | 12 panels |
| 750 kWh/mo | 14 panels | 5.6 kW | 18 panels |
| 900 kWh/mo | 17 panels | 6.8 kW | 22 panels |
| 1,000 kWh/mo | 19 panels | 7.6 kW | 24 panels |
| 1,500 kWh/mo | 28 panels | 11.2 kW | 36 panels |
| 2,000 kWh/mo | 37 panels | 14.8 kW | 48 panels |
What 5.8 hours means in practice
California sits in the strong tier of American sun, 4th of 50 at 5.8 hours, 29% above the national average. In panel terms the 900 kWh average bill needs 17 panels here instead of the US-average 22. Systems this far into the Sun Belt usually pencil on production alone; the variables that actually kill quotes here are shade and roof direction, not the resource.
For a location-exact figure, run your address through NREL's free PVWatts; it uses measured weather for your grid cell and will also model roof tilt and direction, which statewide numbers cannot. Then compare its annual kWh against a quote's promise before you sign anything.
Questions people ask
How many solar panels do I need in California?
About 17 400-watt panels (6.8 kW) for the 900 kWh a month an average US home uses, at California's 5.8 peak sun hours. Your bill is the variable that matters: the table on this page covers 500 to 2,000 kWh, and the calculator takes any figure.
Is 5.8 peak sun hours good for solar?
Yes, comfortably. California ranks 4th of the 50 states, 29% above the national average, which means fewer panels per kWh of bill than almost anywhere else in the country.
Do peak sun hours change with the seasons in California?
Yes, everywhere: the figure on this page is the annual average of a curve that peaks in June and bottoms out in December. In California the swing is meaningful but manageable; summer typically runs half again the annual figure and December two-thirds or less of it. Grid-tied homes bank summer overproduction as credit; off-grid designs must size for the trough, not the average.