What is a 'request'?
In the simplest of terms, 1x request = 1x year of time-series data for 1x location.
However, in order to determine how many requests you'll need, you may need to consider more than just the number of locations and number of years you'll need data for.
How many requests will I need?
Each of our response formats (API speak for 'file format') count as their own request.
This means you also need to consider the time granularity of the data you require as well as the file format.
For example, if you need both a Solcast CSV and a PVsyst file for one year of data from your location, you will need two requests (1x location and 2x file formats).
Or, if you need both 15 minute and 5 minute time granularity, this would again mean you need two requests (1x location and 2x time granularity selections).
So the maths for figuring out how many requests you need per month works out to be:
Locations * Number of Years
* File Formats Per Location
* Time Granularity Per Location
= API Requests Required