Sources

The public data behind the report.

Every figure traces to one of these. All are public and free to check.

Solar production

NREL PVWatts and the National Solar Radiation Database (NSRDB), the U.S. National Renewable Energy Laboratory's modelling of how much a solar array produces by location. pvwatts.nrel.gov

Electricity rates

OpenEI Utility Rate Database (URDB), your specific utility's published residential rate schedule, maintained by NREL. We use your utility's rate where available. openei.org

U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A, average residential retail price by state, used as a fallback (and a sanity check) when a clean utility rate isn't available. eia.gov/electricity/monthly

Federal tax credit

IRS Residential Clean Energy Credit (26 U.S.C. §25D), the 30% federal credit for residential solar, in effect through 2032. irs.gov

State & local incentives

DSIRE, the Database of State Incentives for Renewables & Efficiency, maintained by NC State University. The authoritative index of state tax credits, rebates, and net-metering rules. dsireusa.org

Installed cost benchmark

NREL and SEIA residential PV cost benchmarks (~$3.00/W, 2024), used as the yardstick for judging installer quotes.