Solar Panels in Mercer Island, WA: Cost, Payback & Savings
A typical 11.2 kW home solar system in Mercer Island costs about $33,600 and pays for itself in about 16.9 years, saving roughly $20,349 over 25 years at Washington's average electricity price of 14.4¢/kWh.
Monthly solar production in Mercer Island
Estimated output of a 11.2 kW south-facing roof system. Jul is the strongest month (1,584 kWh); Dec the weakest (373 kWh).
Solar production (kWh) Typical home use, 955 kWh/month
Solar payback calculator for Mercer Island
Pre-filled with Mercer Island's sunshine and Washington's average electricity price. Enter your own bill and an installer's price per watt to see your payback.
Leave export credit blank where the utility offers full net metering. Where exports earn less, solar used at home as it's produced is worth the full price and the rest earns the export credit.
How Mercer Island compares
- Each kW of panels here produces about 1,046 kWh a year — about the same as the Washington median and 24% less than the US median city (1,371 kWh).
- Payback ranks #79 of 133 Washington places we cover.
- Sunshine varies little across a state; electricity price, installed cost and how utilities credit exported power drive most of the difference between states.
Net metering, tax credits and incentives in 2026
Washington offers net metering: power you send to the grid is credited at or near the retail price, so every solar kWh is valued at 14.4¢ here.
There is no federal tax credit for buying home solar installed in 2026. The 30% Residential Clean Energy Credit (Section 25D) ended for systems placed in service after December 31, 2025, so the costs and paybacks on this page include no federal credit.
Washington and local utilities may still offer rebates, performance payments, property-tax or sales-tax exemptions. Search the DSIRE incentives database for Washington and ask installers which programs they apply for you.
Frequently asked questions
Is solar worth it in Mercer Island, WA?
For a typical home, a solar system pays for itself in about 16.9 years and then keeps saving money. Over 25 years the estimated net savings are $20,349. Verdict: slow payback. Your own payback depends on your roof, your bill and the quotes you get.
How many solar panels do I need in Mercer Island, WA?
A home using 955 kWh a month (the Washington average) needs about 28 panels of 400 W — a 11.2 kW system — to cover its annual use. Divide your own yearly kWh by 1,046 to get the kW you need.
How much do solar panels cost in Mercer Island, WA?
At 3.00 dollars per watt, a 11.2 kW system costs about $33,600 before any state or utility incentives. There is no federal tax credit for systems installed in 2026.
How much sun does Mercer Island get?
Mercer Island averages 3.8 peak sun hours per day, so each kilowatt of panels produces about 1,046 kWh a year.
Does Washington have net metering?
Yes. Power sent back to the grid is credited at or near the retail price (14.4¢ per kWh on average).
How much does electricity cost in Washington?
Residential electricity in Washington averages 14.4¢ per kWh, and a typical home uses 955 kWh a month (EIA).
Solar payback in nearby places
- Columbia City16.8 yrs
- Bellevue16.8 yrs
- Newcastle16.8 yrs
- Bryn Mawr-Skyway16.6 yrs
- West Lake Sammamish17.6 yrs
- Seattle16.4 yrs
- Renton16.4 yrs
- Tukwila16.6 yrs