Three external data sources feed this site. None require an account to check, and each page that uses one links back to the exact record.
Solar generation — NREL PVWatts v8
Hourly generation for 318 locations, three tilt angles each (flat, latitude, latitude + 15°), from the NSRDB typical-meteorological-year dataset. Public domain (US government work). We apply a 14% system-loss default and derate for the controller type ourselves — PVWatts' own output is the un-derated DC array output.
Climate — NOAA NCEI GHCN-Daily
design_low_c and record_low_c come from the Global Historical Climatology Network-Daily archive: the nearest station (within 60 km, similar elevation) with at least 25 complete years of TMIN data between 1991 and 2020. Public domain.
Panel electrical specs — California Energy Commission list via NREL SAM
A subset of the panels catalog (marked in each panel's Datasheet section) comes from the CEC-approved PV module list redistributed by NREL's System Advisor Model, rather than a fetched manufacturer datasheet PDF — used only for well-established commercial modules where the manufacturer's own datasheet is not reachable.
Everything else
Every other number — component specs, kit contents, appliance wattages — is read from a manufacturer's own product page, manual or datasheet PDF, one field at a time, with the exact quoted text kept alongside it (not published, but available on request). A component with no verifiable source stays out of the catalog rather than getting an invented number.
These results are for reference. Wiring must be installed by a qualified electrician. Mobile installations follow ABYC E-11; stationary ones NEC 690/706.