Washington pays about 11.5¢ per kilowatt-hour for residential electricity and receives about 3.7 kWh per square metre per day of sunlight — 49th and 50th respectively among the 50 states and DC tracked here. Those two numbers set the ceiling on what rooftop solar returns in Washington, and they point in the same direction.
Where Washington sits against the rest of the country
Washington is 3.3¢/kWh below the median residential rate across this dataset (14.8¢/kWh) and 0.9 kWh/m²/day below the median insolation (4.6 kWh/m²/day). Under this site's standard assumptions, that combination puts Washington 51st of 51 for modeled payback speed, at 20.6 years against a dataset median of 13.5 years.
What actually drives payback in Washington
Washington ranks in the lower half on both inputs — 49th for electricity price and 50th for sunlight. Swap Washington's sunlight for the dataset median and payback moves to 17.3 years (3.3 years of swing). Swap its electricity rate instead and payback moves to 16.8 years (3.8 years of swing). The rate swap is the larger of the two, so what a kilowatt-hour costs is the input deciding the outcome in Washington.
State incentives on record
Recorded for Washington: Sales tax exemption (full for systems up to 100 kW); net metering retained; no statewide cash incentive after production-incentive sunset 2020.
No federal credit is applied above (Section 25D expired 31 December 2025), and export terms often matter more than the headline rate (net metering guide).
The modeled system, in numbers
At Washington's sunlight level a 7 kW array produces roughly 7,374 kWh a year, worth about $848 in first-year bill savings at 11.5¢/kWh against an assumed $22,400 installed cost. A ten-year payback at this sunlight level would require a residential rate of about 27.2¢/kWh, which is 15.7¢ above what Washington households pay today.
States with comparable economics
Washington's closest analogues by modeled payback are Oregon (17.4 years), North Dakota (17.4 years), Montana (16.6 years). They arrive there from different rate and sunlight combinations, so their incentive rows are the useful comparison.
- Oregon — modeled payback 17.4 years
- North Dakota — modeled payback 17.4 years
- Montana — modeled payback 16.6 years