PVWatts vs Website Carbon

PVWatts estimates the energy production and cost of grid-connected photovoltaic systems anywhere in the world, given basic system specs like capacity, tilt, and array type. The National Renewable Energy Laboratory's developer portal was renamed to the National Laboratory of the Rockies (NLR) and its host retired on 2026-05-29 — the API itself is unchanged, just served from developer.nlr.gov instead of the old developer.nrel.gov, which no longer resolves.

Website Carbon estimates the CO2 emitted by loading a web page, based on page weight and whether the host uses green hosting, returning a digital carbon rating alongside the raw gCO2e figure. As of 14 July 2025 the provider retired public access to its convenience /site endpoint (which fetched a URL for you); the /data endpoint, which takes bytes and a green-hosting flag directly, remains free and open with no key.