Solar Calculator for Washington: Costs, Incentives & ROI
Washington State presents a solar market defined by a compelling paradox: electricity rates among the lowest in the nation—sustained by the Columbia River's vast hydroelectric infrastructure—sit alongside a net metering framework, sales tax exemption, and business and occupation tax relief that make rooftop solar increasingly attractive to the right household profile. The Washington Utilities and Transportation Commission requires investor-owned utilities, including Puget Sound Energy and Pacific Power, to credit excess solar generation at the full retail rate under the state's net metering program. Seattle City Light, the municipally owned utility serving the state's largest city, operates its own net metering program with equivalent full-retail-rate crediting for systems up to one hundred kilowatts. Washington does not levy a state income tax, which eliminates the possibility of a state-level solar tax credit but also means homeowners can claim the federal thirty-percent Investment Tax Credit against federal tax liability without any state claw-back. Solar photovoltaic equipment and installation labor are exempt from Washington's Retail Sales Tax under RCW 82.08.962, and qualifying solar energy systems are exempt from the Business and Occupation tax under RCW 82.04.4496. Eastern Washington—encompassing the Spokane metro, Tri-Cities corridor, and Yakima Valley—receives substantially more solar irradiance than the overcast Puget Sound basin, producing economics more comparable to Colorado or Nevada. Use the calculator below to estimate your payback period and 25-year savings based on your ZIP code, utility territory, system size, and electricity consumption.
Incentive data updated: May 2026(may be outdated)
Average Solar Cost in Washington
Average installed solar costs in Washington typically range from $2.60 to $3.10 per watt before incentives, based on Lawrence Berkeley National Laboratory Tracking the Sun data and EnergySage marketplace pricing for the Pacific Northwest. A typical six-kilowatt residential system costs roughly $15,600 to $18,600 before the federal Investment Tax Credit, slightly below the national average due to Washington's lower labor and overhead costs compared to California or the Northeast. The thirty-percent federal ITC reduces that net cost to approximately $10,900 to $13,000. Washington's sales tax exemption on solar equipment and installation labor—applied at the point of sale by the contractor rather than through a subsequent rebate claim—directly lowers the upfront system price. In eastern Washington markets such as Spokane, Kennewick, and Yakima, lower permitting complexity and competitive installer pricing can push system costs toward the lower end of the range. The combination of federal ITC, sales tax savings, and net metering at the full retail rate makes solar financially viable across the state, though homes in eastern Washington with higher irradiance tend to achieve shorter payback periods than equivalent systems in the cloudier western lowlands.
- Avg. installed cost
- $2.85/W
- Typical 6 kW system
- $15,600–$18,600
Top Solar Incentives in Washington
Live incentive data not currently available for Washington. See the federal incentive guidance via our Solar Tax Credit Calculator.
Electricity Rates in Washington
Washington's residential electricity rates are among the lowest in the continental United States, averaging approximately 10 to 11 cents per kilowatt-hour statewide, reflecting the massive hydroelectric capacity of the Columbia River system that supplies roughly seventy percent of the state's generation. Puget Sound Energy customers in the western lowlands typically pay a blended rate between 10 and 13 cents per kilowatt-hour when standard delivery charges are included. Pacific Power customers in eastern Washington see similar blended rates, while Seattle City Light customers benefit from some of the most affordable residential rates of any major urban utility in the country, typically between 9 and 11 cents per kilowatt-hour depending on consumption tier. The low rate environment extends payback periods relative to high-cost states like California, Massachusetts, or New York, where solar avoids a more expensive kilowatt-hour per unit of production. However, Washington utility rates have trended upward over recent years as utilities invest in grid modernization, wildfire-hardening of transmission infrastructure, and clean energy transition compliance under Washington's Climate Commitment Act. Each incremental rate increase improves the long-run economics of a solar installation already in service, and the full-retail-rate net metering credit ensures that excess production retains its value.
Peak Sun Hours in Washington
Washington's solar resource divides sharply along the Cascade crest. The western slopes and Puget Sound basin—covering Seattle, Tacoma, Olympia, and Bellingham—average between 3.5 and 4.2 peak sun hours per day, reflecting the marine climate's persistent cloud cover from October through March. Eastern Washington occupies an entirely different solar environment: Spokane, the Tri-Cities (Kennewick, Pasco, Richland), and Yakima regularly achieve between 4.5 and 5.5 peak sun hours per day, placing the region on par with parts of Colorado or the Great Basin. For western Washington homeowners, the lower annual irradiance means a given system produces fewer kilowatt-hours per installed kilowatt than an identical system in a sunbelt state, which the installer's production estimate should account for. NREL's PVWatts tool draws on ZIP-code-level Typical Meteorological Year data that captures Washington's regional variation, so the production estimate from the calculator above reflects your specific location's sun exposure rather than a misleading statewide average.
Example ROI for a 7 kW System
- Estimated annual savings
- $1,050
- Payback period
- 11.5 years
- 25-year net savings
- $16,000
Run a personalized estimate with your ZIP code using the Solar ROI Calculator.
Major Cities in Washington
- Seattle98101
- Spokane99201
- Tacoma98401
- Bellevue98004
- Olympia98501
Common Questions About Solar in Washington
Does Washington State have a solar incentive program beyond the federal ITC?
Washington's primary state-level solar incentives are tax exemptions rather than cash payments. The Retail Sales Tax exemption under RCW 82.08.962 eliminates Washington's 6.5 percent base sales tax (plus any local add-on) from the purchase price of solar equipment and installation labor — for a $17,000 system this can represent $1,100 or more in direct savings. The Business and Occupation tax exemption under RCW 82.04.4496 provides additional relief for solar energy system businesses. Washington does not currently offer a production-based incentive or a state income tax credit, since the state has no income tax. The federal thirty-percent Investment Tax Credit remains the dominant financial driver, and full-retail-rate net metering provides ongoing annual bill savings.
How does net metering work in Washington State?
Washington's net metering program, governed by the Washington Utilities and Transportation Commission under WAC 480-108, requires investor-owned utilities — including Puget Sound Energy and Pacific Power — to credit excess solar generation at the full retail rate on a kilowatt-hour-for-kilowatt-hour basis. Excess credits typically roll over monthly and are reconciled at the end of a twelve-month annualization period; credits remaining at year-end may be paid out at the utility's avoided-cost rate, which is generally lower than retail. Seattle City Light operates an equivalent program for its service territory. Systems up to one hundred kilowatts are eligible. The full-retail-rate credit is the most financially significant aspect of Washington net metering — each exported kilowatt-hour avoids the full retail purchase price rather than being compensated at a discounted export tariff.
Is solar worth installing in Seattle given the cloudy weather?
Yes, for the right household profile. Seattle's western Washington solar resource averages 3.5 to 4.2 peak sun hours per day — lower than the national average but sufficient for economic solar production when combined with the full-retail-rate net metering credit, the federal ITC, and the sales tax exemption. The low electricity rate is the primary factor that extends payback periods in the Seattle area compared to higher-rate states, but rate increases under Washington's Climate Commitment Act compliance trajectory improve long-run economics for systems already installed. Homes with high electricity consumption, south-facing unshaded roofs, and the ability to fully utilize the federal tax credit benefit most. Eastern Washington homeowners with 4.5 to 5.5 peak sun hours per day see meaningfully shorter payback periods — often in the nine-to-twelve-year range — than their western counterparts.
Are there property tax exemptions for solar in Washington?
Washington does not have a statewide solar property tax exemption equivalent to those in New Jersey, Colorado, or Maryland. However, some Washington counties and municipalities may assess solar installations conservatively, and the county assessor's office is the authoritative source for how an installation will affect your assessed value. The more significant tax protections in Washington are the sales tax exemption on purchase and installation and the B&O tax exemption — both apply statewide and reduce the upfront cost rather than the ongoing tax assessment. Homeowners should verify current assessment practice with their county assessor before assuming no property tax impact.
How does eastern Washington compare to western Washington for solar?
Eastern Washington receives substantially more solar irradiance than the Puget Sound basin. Cities like Spokane, Kennewick, Richland, Pasco, and Yakima average between 4.5 and 5.5 peak sun hours per day, while Seattle, Tacoma, and Olympia average 3.5 to 4.2. This difference can reduce payback periods in eastern Washington by two to four years compared to equivalent systems on the west side of the Cascades, assuming the same electricity rates and net metering structure. Eastern Washington homeowners served by Pacific Power benefit from the same full-retail-rate net metering credit as PSE customers in the west, but their systems produce more kilowatt-hours per installed kilowatt. For a seven-kilowatt system, the difference in annual production between a Spokane and a Seattle installation can exceed 1,000 kilowatt-hours.