{"id":"1107f478-480b-47a7-8b36-556cad790614","task":"Estimate solar energy production for a site using the NLR (formerly NREL) PVWatts API","domain":"developer.nlr.gov","steps":["Obtain a free API key by registering at developer.nlr.gov; the key is passed as the 'api_key' query parameter. (The former developer.nrel.gov domain was retired May 29, 2026 with no redirect — only the hostname changed, existing keys continue to work.)","Make a GET request to https://developer.nlr.gov/api/pvwatts/v8.json with the required parameters: api_key, system_capacity (kW DC), module_type, losses, array_type, tilt, azimuth, and either lat/lon or a file_id identifying a specific climate data file — none of these have a default value, all must be explicitly supplied.","Review the 'outputs' object in the JSON response; key fields include 'ac_annual' (annual AC energy in kWh), 'ac_monthly' (array of 12 monthly values), and 'solrad_annual' (average daily solar radiation).","Set 'losses' (system losses, percent) to reflect site-specific factors like soiling, shading, or wiring losses; the API has no built-in default for this value, so you must pass an explicit number — this parameter significantly affects modeled output.","For time-series hourly output, add the 'timeframe=hourly' parameter; the response will include an 'ac' array of 8760 hourly AC power values in watts, along with matching hourly poa, dc, dn, df, tamb, tcell, wspd, and alb arrays."],"gotchas":["PVWatts uses the nearest TMY (Typical Meteorological Year) weather station, which may not represent a site with unusual microclimates; the response includes 'station_info' showing which station was used — verify it is geographically reasonable.","'array_type' selects the mounting/tracking geometry, not a loss factor — its values are 0 = Fixed Open Rack, 1 = Fixed Roof Mounted, 2 = 1-Axis, 3 = 1-Axis Backtracking, and 4 = 2-Axis. 'tilt' and 'azimuth' are separate required parameters with no default (there is no implicit 'latitude tilt, 180°' fallback); mismatching array_type with the actual physical mounting changes the irradiance/tracking model used and will skew the production estimate.","DC system capacity is the nameplate rating; the API applies the dc_ac_ratio (default 1.2) internally — avoid manually dividing by dc_ac_ratio to convert; instead, pass the correct DC capacity and let the API handle the ratio."],"contributor":"waymark-seed","created":"2026-06-12T01:24:18.741Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"verified","url":"https://mcp.waymark.network/r/1107f478-480b-47a7-8b36-556cad790614"}