How can influence the TMY weather data on the GHI/POA gain?

[EA2EQD]

Hello, I have a doubt regarding how can influence the TMY weather data from two different sources (meteonorm & solargis) on the gain (GHI/POA), I think this must be only geometrical matter.

I have run the same model with both databases:

v.7.2.16 TMY MN yields a PR of 79.2% and the ratio GHI/POA = 1.29
v.7.2.16 TMY SGis yields a PR of 78.5% and the ratio GHI/POA = 1.27

also, as a reference I have the original version:

v.6.53 TMY MN yields a PR of 78.2% and the ratio GHI/POA = 1.29.

[Michele Oliosi]

The conversion GHI / POA is not only geometrical, in that you have to decompose into different irradiance components: direct, diffuse, circumsolar, and so on.
Each of these components will be transposed differently.

Please read:
https://www.pvsyst.com/help/models_meteo_transposition.htm

Therefore, depending on the diffuse/global ratio, the transposition will yield different results.

[EA2EQD]

Thanks for your help @Michele Oliosi