Danish data service Energi vs PVWatts

Energi Data Service is the Danish transmission system operator Energinet's open-data platform, publishing dozens of live datasets — day-ahead power prices, grid emissions, consumption, and more — as a free public JSON API with no key required. Its older Elspotprices dataset was retired after the Nordic market's move to 15-minute settlement on 2025-09-30, superseded by the still-live DayAheadPrices dataset.

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.