Diffuse irradiation generation

[jdelapena]

Good afternoon

When I create a geographical site I only put as inputs "Horizontal global irradiation" and "Average Ext. Temperature". If I had "Horizontal diffuse irradiation" from a data base, should I put it as input too?

I would like to know how PVsyst generate "Horizontal diffuse irradiation". I thought that "Horizontal global irradiation include" included diffuse irradiation, is it correct?

Thank you

[André Mermoud]

When creating a synthetic hourly data file (from external monthly data), PVsyst uses the algorithm which is included in the Meteonorm program (DLL used in PVsyst). During this process, the program Meteonorm establishes the Diffuse component (from global) using the Perez-Ineichen model (also named DirInt).

Now if you specify Monthly values for the diffuse, PVsyst will renormalize the Diffuse computed from the model, in order to get the exact specified Monthly sum.