California pays about 31.7¢ per kilowatt-hour for residential electricity and receives about 5.7 kWh per square metre per day of sunlight — 2nd and 4th respectively among the 50 states and DC tracked here. Those two numbers set the ceiling on what rooftop solar returns in California, and they point in the same direction.
Where California sits against the rest of the country
California is 16.9¢/kWh above the median residential rate across this dataset (14.8¢/kWh) and 1.1 kWh/m²/day above the median insolation (4.6 kWh/m²/day). Under this site's standard assumptions, that combination puts California 2nd of 51 for modeled payback speed, at 5.9 years against a dataset median of 13.5 years.
What actually drives payback in California
California ranks in the upper half on both inputs — 2nd for electricity price and 4th for sunlight. Swap California's sunlight for the dataset median and payback moves to 7.1 years (1.3 years of swing). Swap its electricity rate instead and payback moves to 11.6 years (5.8 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 California.
State incentives on record
Recorded for California: NEM 3.0 (Net Billing Tariff) since April 2023 sharply reduced export credits; SGIP battery rebate; DAC-SASH for low-income households; property tax exclusion through 2026-12-31.
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 California's sunlight level a 7 kW array produces roughly 11,360 kWh a year, worth about $3,601 in first-year bill savings at 31.7¢/kWh against an assumed $22,400 installed cost. A ten-year payback at this sunlight level would require a residential rate of about 17.7¢/kWh, which California already exceeds.
States with comparable economics
California's closest analogues by modeled payback are Hawaii (4.6 years), Massachusetts (7.8 years), Connecticut (8.0 years). They arrive there from different rate and sunlight combinations, so their incentive rows are the useful comparison.
- Hawaii — modeled payback 4.6 years
- Massachusetts — modeled payback 7.8 years
- Connecticut — modeled payback 8.0 years
California-specific notes
California's 2023 shift to NEM 3.0 (the Net Billing Tariff) sharply reduced export credit for new investor-owned-utility customers. The state economics now favour solar paired with battery storage, which lets households self-consume daytime production rather than exporting it at the lower rate. Plan for a battery or expect payback to stretch beyond the figure modeled above, which assumes production is valued at the retail rate.