Solar panels in Federal Way, WA
Roofs in Federal Way get about 1,249 hours of usable sunlight a year — less than 97% of the cities we've measured. Here's what that means in cost, savings and payback, using real rooftop data rather than a national average.
Check your specific roof in Federal Way → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Federal Way solar system costs
A 26-panel system (10.4 kW) is about right for an average Federal Way home using 10,800 kWh a year. It would produce roughly 11,041 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 3,397 | $6,384 | $384 | 16.6 yrs |
| 12 panels | 4.8 kW | 5,096 | $9,576 | $576 | 16.6 yrs |
| 16 panels | 6.4 kW | 6,795 | $12,768 | $768 | 16.6 yrs |
| 20 panels | 8 kW | 8,493 | $15,960 | $960 | 16.6 yrs |
| 26 panels | 10.4 kW | 11,041 | $20,748 | $1,227 | 16.9 yrs |
Notice that payback barely improves as systems get bigger, and eventually gets worse. That's because you can only save money on electricity you were going to buy anyway. Once a system covers your usage, extra panels mostly generate exports at a much lower rate.
Why Federal Way gets 1,249 sun hours
That figure comes from Google's analysis of real rooftops across Federal Way — it already accounts for shading from trees, chimneys and neighbouring buildings, which is why it's lower than the raw "hours of daylight" figures you'll see elsewhere. An unusually open, unshaded roof in Federal Way reaches about 1,327 hours, roughly 6% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,249 hrs/yr |
|---|---|
| Unshaded roof | 1,327 hrs/yr |
| Electricity rate (Washington avg) | 11.3¢/kWh |
| Installed cost assumed | $2.85/W |
| Panel size assumed | 400 W |
| Federal tax credit | 30% |
| Typical household usage | 10,800 kWh/yr |
| Power used as generated | 34% |
| Paid for exported power | full retail (net metering) |
| Rooftops sampled here | 12 |
| Google imagery from | 2024 |
Nearby cities
See all of Washington → statewide sunlight, rates, incentives and every city we've measured.
Federal Way solar questions
How many solar panels do I need in Federal Way?
About 26 panels for an average home. Federal Way roofs get 1,249 usable sun hours a year, so each 400W panel produces roughly 425 kWh annually.
Is solar worth it in Federal Way?
At 11.3¢/kWh and 1,249 sun hours, a typical system pays for itself in about 16.9 years and returns roughly $9,932 over 25 years. That is slower than the national average, so compare quotes carefully.
How much do solar panels cost in Federal Way?
A 10.4 kW system costs about $29,640 before incentives and $20,748 after the 30% federal tax credit. Prices vary by installer, roof complexity and equipment.
Worth reading before you buy
Estimates only, generated 2026-08-22 from Google Solar API rooftop samples and average Washington electricity rates. Not a quote and not financial advice. Your roof, usage, utility plan and local incentives will change these numbers — get real quotes before buying.