Washington has 1:1 retail net metering today and a strong sales tax exemption that runs through 2029. Our model puts typical residential payback near ~17.5 years — close to Montana's, slightly better because Washington's sales tax exemption (state 6.5% plus local, up to ~10% combined) saves real money at install.

The reason payback is long isn't bad rules. It's the price of electricity. Washington residential retail averages ~15¢/kWh thanks to abundant hydropower — about 27% below the US average. Under 1:1 net metering, each kWh of solar you produce is worth roughly that retail rate, and 15¢ isn't a lot. The same arithmetic that makes Montana payback long (cheap power → small savings per kWh) applies in Washington.

There's a fresh, important caveat specific to Washington: 2026 is likely the LAST YEAR of 1:1 net metering for new installs. PSE and Seattle City Light have officially notified customers they are moving to a new payment structure. Unlike Virginia — where the SCC preserved 1:1 in April 2026 — Washington's utilities are actively changing it. Verify with your utility before signing.

What changed

The federal Residential Clean Energy Credit (§25D) — the 30% homeowner credit — was repealed for systems installed after December 31, 2025. For 2026 Washington buyers, the federal credit on a purchased system is $0. The same applies to home batteries purchased outright. The §48E commercial credit (30%) still exists, but only for leased or third-party-owned systems — the lessor claims it, not you. Full federal context here.

VERIFIED 2026-06 · irs.gov

Net metering: 1:1 today, changing soon

Washington law (RCW 80.60) requires the major utilities — PSE (modeled here), Avista, Pacific Power, Seattle City Light, and Snohomish PUD — to offer full retail 1:1 net metering for residential systems up to 100 kW. Grays Harbor PUD is an exception (50% of retail) and is not modeled here.

The fresh news that matters most. PSE and Seattle City Light have officially notified customers that they are moving to a new payment structure. 2026 is likely the last year of 1:1 net metering for new installs at those utilities. The exact replacement structure, effective dates, and grandfathering rules for existing customers vary and are still being finalized.

This is the opposite of what happened in Virginia earlier in 2026: there, the SCC preserved 1:1 by rejecting Dominion's NEM 2.0 proposal in April. In Washington, the utilities are driving the change themselves. If you're considering solar in WA, verify the current structure with your specific utility before signing — by the time you install, it may already have changed. This calculator models the current 1:1 PSE case, which is what the rules say today.

VERIFIED 2026-06 · WA RCW 80.60; PSE and Seattle City Light customer notices

The driver: ~15¢/kWh retail (hydropower, but rising)

Washington's residential retail averages about ~15¢/kWh on PSE, ~27% below the US average. That's the structural advantage of Washington's grid — abundant hydropower keeps generation costs low. Eastern WA (Avista) and public utilities (Seattle City Light, Snohomish PUD) generally run lower still.

The catch: rates are rising fast. PSE raised rates about 12% in January 2026 alone, and the trend is upward. Higher future retail makes future self-consumption more valuable, which improves the lifetime value of any solar system installed today — but the headline payback number reflects today's rates.

The same arithmetic that long-time Washington residents know about heat pumps and electric heating applies to solar: cheap power is great for your bill, but it makes capital-intensive offset investments harder to justify on payback alone.

VERIFIED 2026-06 · eia.gov

No state income tax credit — and the production incentive is GONE

Washington has no state income tax at all, so there's no state-level solar income tax credit. This is the same structural reason TX, FL, NV, AK, and SD don't have state solar credits — no income tax to credit against.

The thing to actively reject is the Renewable Energy System Incentive Program — a production-based incentive that used to pay residential solar customers around ~$0.54/kWh of production. It has ENDED. Sources still citing it as a current Washington solar incentive are out of date.

If a quote, contractor proposal, or blog claims you'll receive Washington's "$0.54/kWh production incentive" or a "production incentive payment" in 2026, the math is wrong. The program is gone.

Sales tax exemption — strong, but already in your installed price

Washington exempts solar systems up to 100 kW from state and local sales tax through December 31, 2029. State sales tax is 6.5%; combined with local sales tax, the all-in rate in Washington can hit ~10%. On a typical $15,000+ residential system, that's roughly $1,000+ saved at install.

This is one of Washington's strongest current solar incentives. Read this part carefully so you understand how it shows up:

The exemption is "in your price." Your installed quote from a contractor should already reflect zero sales tax — the exemption isn't a separate line item on the calculator that subtracts an additional amount from your installed cost. It's the reason your installed cost is what it is. If a contractor quote does show sales tax on your solar install, ask why — they shouldn't be charging it through 2029 on systems under 100 kW.

In the calculator above, you'll see the sales tax exemption listed in the Exemptions card as confirmed for Washington. The dollar savings are real but already implicit in your gross cost figure, not a separate subtraction.

For comparison, Maryland's MEA grant ($1,000 upfront) IS modeled as a separate subtraction in our calculator because it's a cash grant after install, not the absence of a tax. The structural difference matters for how the number shows up on your screen.

Property tax exemption also applies in Washington: the added home value from solar is exempt from property tax assessment.

VERIFIED 2026-06 · WA Department of Revenue — sales tax exemption through Dec 31, 2029

Battery in Washington — weak today, important tomorrow

Under Washington's current 1:1 retail net metering, the retail-vs-export gap is effectively zero — like Florida, Virginia, Montana, and the other 1:1 retail states. On pure energy arbitrage, a battery in WA today doesn't pay off. With moderate retail (~15¢), the resilience case is also modest — less avoided cost per outage hour than in Massachusetts or Hawaii.

But that's likely to change. If PSE and Seattle City Light shift to a below-retail export structure (which their notices suggest), the retail-vs-export gap will open up. The economic case for a battery gets stronger in that scenario, similar to how California's NEM 3.0 shift flipped batteries from "doesn't pay off" to "is the lever." Hawaii and California are where battery economics actually work today; Washington could move in that direction depending on the new payment structure.

There's no federal credit on the battery purchase in 2026 (§25D repealed), and Washington has no state battery incentive. If you're installing solar in late 2026 or 2027, verify your utility's structure before deciding on a battery — the answer may be different from what's true today.

The honest picture

Washington solar in 2026:

Washington isn't a bad solar state in terms of rules — current 1:1 net metering is strong, sales tax exemption is strong, property tax exemption is real. The challenge is that cheap hydropower-powered electricity makes solar savings per kWh small, the same way it does in Montana. The federal credit being gone hurts. The lack of any state credit hurts. What's unusual about Washington is the timing: you might be installing into the last year of 1:1 net metering, or into the first year of a less generous structure — verify before you sign.

Before you commit:

Run your real Washington payback →

Estimates only — net metering structure is actively changing (2026 likely the last 1:1 year); sales tax exemption runs through 2029. Verify current rules with your utility. This is not financial advice.