Research Methodology
How We Research Solar Energy Data
Our solar cost, savings, and installation data comes from federal databases, utility filings, and certified installer surveys.
Our Data Sources
NREL solar resource data
Solar irradiance, production estimates, and system performance data are sourced from the National Renewable Energy Laboratory (NREL) PVWatts Calculator and solar resource databases.
EIA utility rate data
Electricity rates and utility pricing used in payback calculations come from the U.S. Energy Information Administration (EIA) Electric Power Monthly.
DSIRE incentive database
Federal and state incentive information (tax credits, rebates, net metering policies) is sourced from the Database of State Incentives for Renewables & Efficiency (DSIRE).
NABCEP-certified installer surveys
Installation cost data is collected from NABCEP-certified solar installers across major U.S. markets quarterly.
How We Keep Information Current
Incentive and rate data is reviewed quarterly. NREL production estimates are updated annually. All payback calculations display the electricity rate and incentives assumed.
Important Caveats
Solar economics depend heavily on local utility rates, roof characteristics, shading, and available incentives. Obtain quotes from multiple NABCEP-certified installers for your specific property.
Questions About Our Research?
If you spot an error, have a question about a source, or want to suggest an update, contact our editorial team at [email protected]. We investigate every reported inaccuracy and respond within 3 business days.