Hi I would like to know how PVsyst calculates DNI values if give a weather data file that contains GHI but does not come with DNI. If it is indeed the case that it uses the Erbs model (DNI = (GHI - DHI)/cos(Z), where Z is the zenith angle), I would like to know how PVsyst handle cases where the zenith angle is 90 degrees (or relatively close to that). Also, is there a way of exporting PVsyst's calculated DNI? It appears the only meteo data closest to DNIthat one can export is the Horizontal Beam Irradiation.
