Solar Panel Cost in Washington: $2.55/W, 18.5-Year Payback

Solar in Washington costs about $20,400 for 8 kW at $2.55/W and pays back in roughly 18.5 years at 14.7¢/kWh with the federal credit at $0.

Updated September 2026 · Source: EIA Electric Power Monthly Table 5.6.A (July 2026 data) · next EIA update ~Oct 23

By SolarCostData Data Desk · Reviewed September 2026 · Corrections log

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Why this number

Solar panels in Washington cost about $2.55 per watt — $20,400 for a typical 8 kW system — and pay back in roughly 18.5 years at the state’s 14.7¢/kWh average rate, with the 2026 federal credit at $0. Full-retail net metering is assumed; confirm with your utility.

Everything below uses Washington’s real average residential electricity rate (14.7¢/kWh, EIA) and a production band of about 1,045 kWh per kW per year. Both are stated openly because they are the two inputs that decide the answer. These are estimates for sanity-checking a quote, not a quote.

Run it with your own numbers

Why Washington’s payback lands where it does

Washington’s rate rose sharply this year, up about nine percent from 13.45 cents per kilowatt-hour in July 2025 to 14.7 cents this July, though it remains a below-average rank-38 rate. The bigger constraint on Washington solar is sun: yield of just 1,045 kilowatt-hours per installed kilowatt is among the lowest in the model, a direct result of the Pacific Northwest’s cloud cover, and it keeps the payback at about 18.5 years even after the rate jump. Puget Sound Energy, the largest utility with over 1.09 million residential customers, prices at 14.6 cents, close to but just under the state average, so its customers should expect a payback near the statewide 18.5-year figure. Full retail net metering credits exported power at that rate, meaning the state’s fast rate growth is the one factor pulling the payback in a favorable direction against a genuinely weak solar resource.

Electric utilities in Washington

The state average hides real spreads between utilities. The largest residential utilities EIA-861 lists for Washington, with each one’s own average bundled residential price (2024 — revenue ÷ sales, the audited annual figure, not this month’s tariff):

Your utility decides Washington’s real number — the ZIP lookup finds it in three clicks; the 2024 annual utility averages above sit apart from the June-2026 monthly 14.7¢ state figure.

Washington’s rate, the last 24 months

July 2025 → July 2026: 13.45¢ → 14.71¢. The rate tracker has every month against the US average.

An 8 kW system in Washington, priced out

The $2.55/W used above comes from EnergySage marketplace quotes (August 2026). Those are quotes in a competitive online market, not signed contract prices.

Read that table with one caveat: $2.55/W is Washington’s market average, and it is the input most likely to differ for you. A quote $0.50 per watt above or below the $2.55 used here moves the payback by roughly a year and a half in either direction.

How much sun Washington actually gets

A kilowatt of panels in Washington produces about 1,045 kWh a year on an unshaded, south-facing roof at a 20-degree pitch. Sites that swap Washington’s 1,045 kWh for a single national average are how Arizona and Washington end up with identical paybacks despite a 1.6x real difference in output.

That figure is a five-point cluster around Seattle. It is a state average, and in Washington that hides a lot: Seattle 1086 to Yakima 1320. Even inside the Seattle metro, Everett is 999. If you are not near Seattle, treat the number as a starting point and run your own address through a modelling tool.

City-level figures for Washington

We have separately modeled production for 6 Washington cities, and they are 32% apart — Everett at 999 kWh per kW against Yakima at 1,320. Installed cost held at $2.55/W; paybacks use each city’s own utility tariff and export treatment where we have official EIA-861 data, which is why some differ sharply from this page’s state-average model.

• Yakima — 1,320 kWh per kW, payback about 19.3 years (on its own utility’s tariff)
• Spokane — 1,195 kWh per kW, payback about 19.8 years (on its own utility’s tariff)
• Seattle — 1,086 kWh per kW, payback about 18.6 years (on its own utility’s tariff)
• Tacoma — 1,046 kWh per kW, payback about 24.1 years (on its own utility’s tariff)
• Bellingham — 1,022 kWh per kW, payback about 18.9 years (on its own utility’s tariff)
• Everett — 999 kWh per kW, payback about 23.8–37.6 years (on its own utility’s tariff)

Those are real PVGIS-NSRDB location points, not the state figure scaled by guesswork. All Washington and other city figures .

Two adjustments matter before you apply this to your own roof:

• Shading and orientation. The 1,045 kWh figure assumes an unobstructed south-facing array. A real Washington roof — its own azimuth and pitch, a tree or a chimney — typically produces 10-25% less; this page models 90% of the ideal, so the 7,524 kWh/year above is already derated from 8,360. A genuinely unshaded south roof can adjust upward in the calculator.
• Year-to-year weather moves output by roughly ±5% either way.

A solar resource this thin usually comes with a real winter, and in a state like Washington the larger energy-bill lever is often heating rather than generation — see heat pump vs gas furnace running costs and our winter heating cost data before assuming panels are the first move. The heat pump vs. furnace cost calculator runs that comparison at Washington’s own 14.7¢/kWh rate.

Why Washington’s price flatters its solar case

A rate table flatters Washington. It ranks 38th of 50 on electricity price — expensive — but only 50th on what a kilowatt of panels actually earns, because a kW here produces roughly 1,045 kWh a year, below the national planning figure. The high rate is real; the sunshine to exploit it is thinner than the price suggests, which costs Washington 12 places. Its immediate neighbors on price are Montana (15.0¢) just above and Mississippi (14.5¢) just below.

Wyoming is Washington’s closest comparable-rate analogue — 14.4¢/kWh, roughly 1,475 kWh per kW, and a payback within about a year of this one (18.1 vs 18.5 years). If you find Washington quotes hard to sanity-check, Wyoming numbers are broadly transferable.

The export question worth asking your Washington utility

Washington credits exported power at the retail rate — full net metering — under RCW 80.60, in force since sunset approaching, so a kilowatt-hour you send to the grid is worth the same as one you buy. That is the best case for solar economics, and it is why the payback above is what it is.

It is also the assumption most likely to change. Twenty-two states have already moved to net billing. If Washington did the same on typical terms, this system would take about 24.4 years to pay back instead of 18.5 — 5.9 years’ difference from a policy change, with no change to the hardware. The households best placed for that day are the ones already storing their surplus, which is why what a home battery actually costs is worth knowing even while full retail holds.

Full retail in statute, but several utilities have hit the 4% cap and moved to successor tariffs, so practice is mixed.

One limit worth knowing: this reflects investor-owned, state-regulated utilities; Washington’s municipal utilities and co-ops are exempt in most cases and set their own terms.

What is actually left in Washington

The 30% federal credit ended for systems completed after December 31, 2025, so it is $0 here as everywhere. What remains is state, utility and local — and it varies far more than the federal rule ever did.

Washington offers no state-level solar tax credit or rebate. Utility-level rebates, and the tax exemptions below, are where any remaining help comes from — those are set locally, so DSIRE and your own utility are the places to look.

Tax exemptions

Sales tax is exempt (6.5% state rate), which keeps roughly $1,326 off the upfront cost of the system modeled here.

There is no property-tax exemption, so a system may raise your assessed value. Ask your assessor what it would add.

If that list looks thin, it is — the solar incentives hub shows which states still put real money on the table, and where Washington sits among them.

Is solar worth it in Washington at 14.7¢/kWh?

Washington is the weakest kind of case for a cash purchase — 14.7¢/kWh power and only about 1,045 kWh per kW. Unless you are buying for backup, resilience or your own reasons, the money almost certainly does more elsewhere.

At a horizon that long, owning the roof is not the only route to cheaper power. Community solar versus rooftop walks through the subscription alternative — no roof, no loan, and no 18.5-year wait — which is worth reading before committing capital in a market like Washington’s.

If you want a fast gut check before running the numbers above, the should-I-go-solar screener asks the four questions that matter most in a low-rate state like Washington.

Two numbers put that in context. At Washington’s rate, the electricity an 8 kW system would produce is worth about $1,107 a year, so the system costs roughly 18.4 years of that output to buy outright — a simple division, before costs. The headline 18.5-year figure above is the full model: it additionally counts 2.5%/yr rate inflation, $150/yr of running costs and one inverter replacement, which is why the two differ slightly. And doing nothing is not free: 25 years of that same electricity, with rates rising at 2.5% a year, comes to about $37,813.

For a 15-year payback in Washington — given its sunshine rather than a national average — the electricity rate would need to be about 18.6¢/kWh. Washington is at 14.7¢, which is below it.

Sources and method

• Electricity rate: U.S. Energy Information Administration, average price by state — EIA Table 5.6.A, July 2026 data (released Sep 2026). Rate shown is Washington’s residential average.
• Production: PVGIS v5.2 with the PVGIS-NSRDB radiation database, 1,045 kWh/kW for a five-point cluster around Washington’s largest metro, then the 90% real-roof factor; the assumptions, the ERA5 cross-check and the attribution are on the methodology page .
• Incentives: DSIRE — Database of State Incentives for Renewables & Efficiency, NC Clean Energy Technology Center. Verify current amounts and fund status before relying on them.
• Federal credit status: IRS, Residential Clean Energy Credit . See our 2026 energy tax credit guide .
• Payback model: shared with the solar savings calculator — 2.5%/yr utility inflation, 0.5%/yr degradation, federal credit $0.

Washington’s rate (14.7¢, EIA Table 5.6.A, July 2026 data (released Sep 2026)), export regime, production factor, installed cost and programs were last verified on 25 September 2026; Washington’s export credit resets on its tariff cycle and incentive budgets run out mid-year, so confirm current terms before acting. Not tax or financial advice.

Frequently asked questions

How we calculated this

Worked for Washington: 8 kW × 1,000 × $2.55/W = $20,400 gross (federal credit $0, so net before state incentives); 7,524 kWh a year × the blended kWh value at 14.7¢ retail ≈ $1,107 year-1 saving; payback ≈ $20,400 ÷ $1,107 = 18.5 years with 2.5%/yr rate growth, 0.5%/yr degradation and one inverter replacement in the 25-year model.

Sources: U.S. Energy Information Administration (EIA) electricity rates · DSIRE incentive records · public IRS/OBBBA guidance. Figures are modeled estimates, not quotes or tax advice. See our methodology.

States with a comparable tariff picture

• Why is my electric bill so high? — Splits a bill jump into weather, rate and usage — with Washington’s own EIA rate history built in.
• Time-of-use rate simulator — PacifiCorp (Pacific Power)’s Schedule 19 — Residential Service: Time of Use Pilot schedule is preset from its own tariff sheet — see whether off-peak pricing beats your flat rate.
• Electricity rate tracker — Washington’s last 24 months of EIA rates, charted against the US average.
• Find your rate by ZIP — Washington averages hide utility gaps — look yours up from EIA-861 in three clicks.
• Net metering by state (2026 table) — Every state’s export regime with program, date and source — the rule behind Washington’s payback.
• Solar panel cost in Montana — Same export regime at 15.0¢/kWh and a 15.2-year payback — the closest tariff comparison to Washington.
• Solar panel cost in Florida — Same export regime at 15.0¢/kWh and a 10.6-year payback — the closest tariff comparison to Washington.
• Solar panel cost in Wyoming — Same export regime at 14.4¢/kWh and a 18.1-year payback — the closest tariff comparison to Washington.