I am trying to build a weather file for historical data. The NOAA isd-lite data has everything I need except solar radiance data and I am trying to find a good source.
The best one I've found so far in the National Solar Radiation Database (http://rredc.nrel.gov/solar/old_data/nsrdb/) but this only seems to have information up to 2015.
My question then is two-fold: - Does anyone know a good source of solar radiation data that is updated fairly frequently (say on a monthly basis)? Free would be ideal, but inexpensive would work. - How important is it to various simulators to have specific historical DNI and DHI data?
