Solar Panel Cost in Washington (2026 Estimate)

BySunMetricLab Editorial Team·Independent solar research and calculators

Data last updated September 10, 2026 · ranks #50 of 50 states for modeled payback

Washington averages about 3.7 peak sun hours a day (below the national average) with an approximate residential electricity rate near 11¢/kWh, on the lower end nationally. In the model used here, an 8 kW system in Washington produces roughly 8,640 kWh a year and trims about $1,000 off annual electricity costs, paying back its net cost in about 17.7 years. Longer paybacks like this are common where power is cheap or sun is limited. In Washington incentives carry more of the case, and shifting usage into daylight hours matters more.

Estimated system cost and payback in Washington

Costs assume roughly $3.00/watt installed for Washington; the net column applies a 30% federal credit for comparison with quotes that include it. Savings and payback use the state's sun hours and rate above.

The 30% federal Residential Clean Energy Credit ended for systems paid for after December 31, 2025 under the 2025 federal budget law. Net-after-credit figures apply only if you still qualify (for example a 2025 expenditure, or a leased system where the installer passes a credit through). Confirm with a tax professional.

What moves the numbers in Washington

Two inputs drive most of the difference between states: how much sun a system sees and what each offset kilowatt-hour is worth. Washington's 3.7 sun hours set production, and its roughly 11¢/kWh rate sets what that production saves. The bigger unknowns are your roof, shading, and how your utility compensates exported power, since a lower export rate can pull real savings below the retail-rate figure above.

Net metering and export credits in Washington

Washington's net metering statute covers systems up to 100 kilowatts and requires every utility to credit exports at the retail rate, kilowatt-hour for kilowatt-hour, until its cumulative net metered capacity reaches four percent of its 1996 peak demand. Credits roll forward month to month, but any surplus remaining on March 31 is zeroed out with no payment, so a system sized to produce far more than you use over a year hands the excess to the utility for free.

Once a utility crosses the capacity threshold it can propose alternative compensation, and a few of the faster-growing service territories have begun that conversation, so ask whether yours is near its cap. Many utilities, including Seattle City Light and Puget Sound Energy, have said they will continue net metering beyond the statutory minimum for now. Interconnection is handled by each utility under its own process, with the Utilities and Transportation Commission overseeing the investor-owned companies.

Washington solar incentives beyond the federal credit

The most important state incentive is the sales tax exemption: solar systems up to 100 kilowatts are fully exempt from state and local sales tax on equipment and installation, which is worth several percent of project cost given Washington's high combined rates, and as of 2026 the exemption runs through the end of 2029. Washington has no state income tax, so there is no tax credit, and the state's older production incentive program closed to new applications once its funding cap was reached.

The Department of Commerce received a federal Solar for All award to build low-income rooftop and community solar programs, and it has also run its own low-income community solar grants; the federal piece has been in flux since 2025, so check what is actually enrolling. Several utilities, including Snohomish PUD and Puget Sound Energy, offer loans, rebates, or battery pilots that come and go with annual budgets.

Utilities and rate plans in Washington

Puget Sound Energy is the largest utility, serving the suburbs around Seattle and much of western Washington, while Seattle City Light and Tacoma Power are big municipal systems, Avista serves Spokane and the east, Pacific Power covers the southeast, and public utility districts such as Snohomish, Clark, Chelan, Grant, Douglas, and Benton serve their counties. Hydropower makes Washington's electricity some of the cheapest in the country, and in mid-Columbia PUD territory rates can be a third of the national average, which stretches solar payback considerably. Puget Sound Energy and Seattle City Light charge closer to typical rates and use tiered residential pricing, making solar more attractive there despite cloudier skies. Eastern Washington gets substantially more sun but pairs it with lower rates.