Washington Solar Guide 2026
Everything Washington homeowners need to know: costs, incentives, net metering policy, and what makes this state unique for solar.
Reviewed by Marcus Vance · Planning data requires verification against your utility and state program source.
Policy dataset review cadence: every 45 days · next review 2026-09-07 · program effective dates and expiration rules must be confirmed in the linked source.
Quick answer
Washington solar economics depend on your roof, utility and quote. This page uses illustrative assumptions of 3.9 peak sun hours, $2.9/W and 10.0 cents/kWh; these are not verified current market averages or account rates.
Notes updated 2026-07-24
- Best for
- Washington homeowners comparing solar costs, incentives, and payback assumptions.
- Inputs needed
- annual kWh usage, utility rate, installed $/W, net-metering policy
- Formula used
- Planning production = system kW x peak sun hours x 365 x (1 - 14.08% losses). Retail-value ceiling = production x assumed retail price; actual export value can be lower.
- Method references
- state incentive data, utility tariff checks, Wattcrunch price benchmarks
Key fact about Washington solar
Washington has the lowest electricity rates in the continental US (~$0.10/kWh) due to abundant hydropower. Solar payback is long (~14 years) - the economics improve significantly with EV charging or heat pumps added.
Peak sun hours
3.9
hrs/day planning assumption
Illustrative energy rate
10.0¢
per kWh
Illustrative install cost
$2.9/W
before incentives
Illustrative 8 kW system in Washington
Annual production
9,785 kWh
Retail-value ceiling, not savings
$979
System cost (est.)
$23,200
Includes 14.08% planning losses. Valuing all production at retail is a ceiling, not a net-billing savings estimate; actual self-use, export rates and ownership costs change the result. No new Section 25D homeowner credit in 2026.
Worked example
Washington: a transparent 8 kW planning example
This example shows how the published Washington assumptions flow through a simple first-pass calculation.
Example household usage
10,800 kWh/year
Estimated production
9,785 kWh/year
Rate used in the example
10.0 cents/kWh
Retail-value ceiling, not bill savings
$979/year before ownership costs
Washington Net Metering Policy
Full retail net metering (Engrossed Senate Bill 5116)
Washington requires full retail net metering. Low electricity rates (~$0.10/kWh) significantly extend payback periods, making WA one of the tougher economic cases for solar despite good policy.
Washington Solar Incentives
Programs require eligibility checks and cannot always be combined. Federal 25D credit is $0 for new homeowner-owned systems in 2026.
- ✓Sales tax exemption on solar systems
- ✓Property tax exemption
- ✓Utility incentive programs (check local utility)
Top Utilities in Washington
Interconnection timeline: 4–10 weeks
State-specific decision guide
What to verify before signing a Washington solar quote
In Washington, the financial result depends on more than sunshine or the headline installation price. Confirm the export rule, program eligibility date, and interconnection timeline for your exact utility before treating a payback estimate as a promise.
Export value
This page models full retail net metering (engrossed senate bill 5116). Ask which tariff and export credit apply to your account, not only which program name appears in the proposal.
Incentive eligibility
Check equipment, income, installer, application, and placed-in-service rules before subtracting an incentive from the quote. Programs can close or change terms.
Interconnection
Budget for the published 4–10 weeks and confirm who pays for a required meter, service upgrade, or engineering review.
Source trail: production assumptions use NREL PVWatts; incentive discovery should be checked against DSIRE; electricity-market context is available from the EIA. Confirm final tax treatment with the IRS and your utility.
Calculate your Washington solar economics
Savings links carry illustrative planning inputs. Replace them with your actual tariff and quote; sizing still needs your usage and production assumptions.
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