Retrieve solar resource data (GHI, DNI, and tilt-at-latitude irradiance) for a location using the NLR (formerly NREL) Solar Resource Data API

Steps

1. Register at developer.nlr.gov for an API key (the former developer.nrel.gov domain was retired May 29, 2026 with no redirect; existing keys continue to work — only the hostname changed); pass it as the 'api_key' query parameter.
2. For average resource data, call GET https://developer.nlr.gov/api/solar/solar_resource/v1.json?api_key=<API_KEY>&lat=<LAT>&lon=<LON>. The 'outputs' object returns avg_dni, avg_ghi, and avg_lat_tilt (average tilt-at-latitude irradiance), each provided as both an annual value and a monthly (jan-dec) breakdown — this endpoint does not return DHI or wind speed.
3. For full hourly/sub-hourly time-series data, use one of the current NSRDB download endpoints (e.g. the GOES Aggregated v4.0.0 dataset), providing lat/lon or a WKT point geometry, year, your email, and the attributes to return such as 'ghi,dni,dhi,air_temperature'.
4. The NSRDB download is asynchronous for large requests: the API returns a download URL or sends a link to the provided email; poll or wait for the file rather than expecting an immediate inline response for multi-year or multi-location requests.
5. Parse the resulting CSV, noting that the first few rows are metadata headers (location, timezone, elevation) before the column headers and data rows begin.