Hawaii ranks #1 for solar panel ROI, with the highest electricity rates in the US and one of the shortest payback periods. High-rate Northeastern states like Massachusetts and Connecticut also rank in the top tier despite fewer sun hours — their expensive electricity makes every kilowatt-hour generated far more valuable than sunshine alone.

The US average solar payback period is about 15 years now that the federal tax credit has expired. The highest-rate states, led by Hawaii, see the shortest paybacks, while lower-rate states like Louisiana and Oklahoma can see 18–20 years. Sun hour data sourced from NREL's Solar Radiation Database.

Yes, in many cases. Massachusetts and Connecticut have electricity rates so high ($0.28–$0.32/kWh per EIA) that solar ROI remains strong despite fewer sun hours. A useful rule: if your rate exceeds $0.15/kWh, solar almost always makes financial sense regardless of location.

A peak sun hour is one hour during which solar irradiance averages 1,000 W/m² — the standard rating condition for solar panels. It is not the same as hours of daylight. Phoenix averages 6.5 peak sun hours per day; Boston averages 4.2, per NREL. Your output in kWh = panel wattage × peak sun hours per day.

Solar ROI = kWh generated × value per kWh. Northeast states like Massachusetts ($0.32/kWh), Rhode Island ($0.31/kWh), and Connecticut ($0.28/kWh) have rates nearly double Arizona's $0.16/kWh (all from EIA). So while a Massachusetts homeowner generates fewer kWh, each one saved is worth far more. Add generous state incentives — Massachusetts SMART program, Connecticut Green Bank — and the Northeast consistently outperforms sun-rich but rate-cheap markets.

Many states offer significant incentives beyond utility net metering. New York offers a 25% state tax credit (up to $5,000) plus NY-Sun Block incentives. New Mexico offers a 10% refundable state tax credit (up to $6,000). Massachusetts has the SMART program (per-kWh performance payments — now strongest when paired with battery storage, as the solar-only adder has fallen to near zero). New Jersey has Solar Renewable Energy Certificates (SRECs). Florida, Texas, and Arizona exempt solar equipment from sales tax. Most states have property tax exemptions so solar-added home value isn't reassessed. Check the DSIRE database for current programs.