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The values of Global correspond to an irralistic "Clearness Index" Kt.


André Mermoud

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PVsyst puts limits to the monthly meteo data, for avoiding erroneous inputs.

These limits are applied on the Clearness Index value (Kt) which is the ratio of the measured irradiation to the extraterrestrial one. Therefore Kt is a measure of the transmission of the atmosphere.

The limits fixed in PVsyst are Kt = 0.12 (months with very covered conditions), and Kt = 0.82 (very sunny months) (0.8 in older versions).

PVsyst also puts a limit to the monthly Diffuse/Global (D/G), established at 0.13 (very sunny days).

Usually the values of "normal" meteo data - all over the world - never exceed these limits.

However the meteo conditions for Chile are really exceptionnal, and sometimes overcome these limits.

You can change them in the Hidden parameters, topic "Miscellaneous".

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