Clear sky detection

[Francesco_M]

Hello,

I would like to kindly ask if it would be possible to obtain additional information about how the best clear sky days are selected for each month.

In the PVsyst tutorial (page 99 "Check the imported data"), online help (Meteo Database > Notes on Meteo >Meteonote8_Hourly data quality check) and forum I have found only general considerations but neither the algorithms nor the threesholds used are described.

So far I have extracted the following information:

- the clear sky model used is the one from Kastens

- the model accuracy range from 2 to 3% (depending on the Linke coefficient).

- best clear sky days days should be close to the clear day model, and never overcome it by more than, say, 5% to 10%

Ktcc (clearness index referenced to the clear day model) is probably used as one of the criteria but I am not sure about the other ones.

Thanks in advance for your time and availability