Core sources
U.S. Energy Information Administration (EIA)
Residential electricity prices, state-level energy statistics and electricity-market reference data.
EnergySage Marketplace
Current residential solar installed-price benchmarks used as external comparison points for state hubs and the Solar Quote Analyzer. These marketplace averages remain separate from Home Solar Atlas homeowner-submitted quote data.
National Laboratory of the Rockies PVWatts
Location-specific photovoltaic energy-production estimates used by the ZIP-level solar calculator.
OpenEI
Utility Rate Database records, distributed-generation tariff references and renewable-energy incentive information.
Google Solar API
Building-level roof geometry, sunshine and panel-layout data where coverage is available.
Google Maps Platform Places
Live local business discovery used by the installer finder. These results are not treated as Home Solar Atlas verified profiles.
IRS and government agencies
Federal tax and policy rules, effective dates and official program guidance.
State agencies and electric utilities
Current rebates, tariffs, net metering or net billing rules, interconnection requirements and program documents.
Equipment manufacturers
Current solar panel and home battery specifications, warranties, datasheets and compatibility information.
How source conflicts are handled
When sources disagree, we prefer the source with direct authority over the specific value: a utility tariff over a statewide average for that utility customer, an agency program document over a marketing summary, and a current manufacturer datasheet over an older third-party specification table.
Market-price benchmarks
External marketplace averages are comparison tools, not Home Solar Atlas market indexes. Where a current state-level solar-price benchmark is published, we use that state figure. Where it is not available, the tool falls back to the current U.S. marketplace average and labels that fallback explicitly.
Freshness
Fast-changing data such as electricity prices, solar pricing, incentives, tariffs and news require more frequent review than physical equipment specifications or long-lived methodology. Pages should show source or review dates where the date materially affects the homeowner decision.
Original Home Solar Atlas data
Homeowner-submitted solar quotes are stored separately from third-party datasets. New submissions are moderated before they are included in public aggregate statistics. State averages and example quotes are not published until at least three approved submissions are available for that state, and public examples do not expose ZIP codes, street addresses or homeowner contact information.