It's great news that you are looking into Solcast's historical data API for your solar radiation data needs. We've got the fastest data delivery system and the best price on the market. Plus, we even offer historical data credits for free to researchers!
When it comes time to check what historical data we have available, you can find everything you need in the API Toolkit. Navigate to the the historical data request page, located here:
Start your request by entering your location of interest, and you'll then see the data availability show up just below the map image.
Review historical data availability without logging in:
Another quick option for checking our historical solar radiation data coverage and availability is at our 'global coverage' page:
Scroll to the bottom of the page, where you'll find the latest information on what data is available, where and when.