Idaho pays about 11.3¢ per kilowatt-hour for residential electricity and receives about 4.9 kWh per square metre per day of sunlight — 51st and 14th respectively among the 50 states and DC tracked here. Those two numbers set the ceiling on what rooftop solar returns in Idaho, and they point in opposite directions.
Where Idaho sits against the rest of the country
Idaho is 3.5¢/kWh below the median residential rate across this dataset (14.8¢/kWh) and 0.3 kWh/m²/day above the median insolation (4.6 kWh/m²/day). Under this site's standard assumptions, that combination puts Idaho 47th of 51 for modeled payback speed, at 16.6 years against a dataset median of 13.5 years.
What actually drives payback in Idaho
Idaho is sunlight-led: 14th for insolation but only 51st for electricity price. Swap Idaho's sunlight for the dataset median and payback moves to 17.5 years (0.9 years of swing). Swap its electricity rate instead and payback moves to 13.3 years (3.4 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 Idaho.
State incentives on record
Recorded for Idaho: State income tax deduction for residential alternative energy device (up to $5,000 first year, $5,000 each next three); net metering retained at Idaho Power.
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 Idaho's sunlight level a 7 kW array produces roughly 9,765 kWh a year, worth about $1,103 in first-year bill savings at 11.3¢/kWh against an assumed $22,400 installed cost. A ten-year payback at this sunlight level would require a residential rate of about 20.5¢/kWh, which is 9.2¢ above what Idaho households pay today.
States with comparable economics
Idaho's closest analogues by modeled payback are Montana (16.6 years), Kentucky (15.9 years), North Dakota (17.4 years). They arrive there from different rate and sunlight combinations, so their incentive rows are the useful comparison.
- Montana — modeled payback 16.6 years
- Kentucky — modeled payback 15.9 years
- North Dakota — modeled payback 17.4 years