Home / Solar by city / Seattle, WA
Solar panels in Seattle, WA
Every figure below is produced by simulating a full year — 8,760 hours — of sun angles, cloud cover, air temperature and wind for Seattle, then running the result through a panel and inverter model. No rules of thumb.
What a system actually produces here
Solar output in Seattle peaks in July and bottoms out in December, a swing of about 4.7×. That seasonal shape matters more than the annual total if your utility settles exports monthly rather than annually — a big summer surplus can be worth much less than the same energy spread evenly.
| Month | Sun (kWh/m²/day) | kWh per kW | 7 kW system |
|---|---|---|---|
| Jan | 0.9 | 32 | 227 |
| Feb | 1.6 | 48 | 338 |
| Mar | 2.8 | 84 | 585 |
| Apr | 4.1 | 109 | 762 |
| May | 5.2 | 131 | 915 |
| Jun | 5.4 | 126 | 884 |
| Jul | 6.0 | 144 | 1,010 |
| Aug | 5.1 | 129 | 903 |
| Sep | 3.6 | 95 | 667 |
| Oct | 2.0 | 62 | 434 |
| Nov | 1.1 | 36 | 250 |
| Dec | 0.8 | 31 | 217 |
Electricity rates
Run your own numbers
Payback depends on what you pay for the system, how much power your household uses after dark, and which incentives you qualify for — none of which a city page can know. The calculator asks for those and settles all 8,760 hours against your actual rate.
See also: solar incentives in Washington — the state credit, the export rules, and what the §25D expiry changed for buyers here.
Other cities
- Phoenix, AZLos Angeles, CASan Francisco, CASan Diego, CAFresno, CALas Vegas, NVSalt Lake City, UTDenver, COAustin, TX
Method
Irradiance is decomposed into beam and diffuse components and projected onto the array plane with the Perez model, with incidence-angle losses, a cell-temperature model driven by air temperature and wind, and an inverter efficiency curve including clipping. Annual yield is checked against NREL PVWatts v8 across all 18 modelled cities; RMS error is 2.70%. See the glossary for what each term means.