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Air quality of China

EU solar radiation and photovoltaic performance estimates.
PVGIS API is a free Environment API that requires no API key, is served over HTTPS and does not support CORS, so it should be called from a server.
All the PVGIS tools can be accessed non-interactively using our web APIs. Check the documentation here.
Details from joint-research-centre.ec.europa.eu.

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Air quality of China
Energy production photovoltaic (PV) energy systems
Compare Italian solar (photovoltaic) installer offers, energy prices (PUN/ARERA) and satellite roof data
The PVGIS API is provided by Joint Research Centre (joint-research-centre.ec.europa.eu). All the PVGIS tools can be accessed non-interactively using our web APIs. Check the documentation here.
Yes. The PVGIS API is listed in the Environment category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
No. The PVGIS API requires no authentication, so you can start making requests without signing up.
Not directly. The PVGIS API does not allow CORS, so call it from a server, serverless function or proxy instead of front-end JavaScript.
Yes. The PVGIS API is served over HTTPS, so it's safe to use in production.