Pérez transposition model, PVsyst vs. satellite database

[EA2EQD]

Hi all,

SolarGis uses the Perez transposition method to pass the irradiance from GHI to Glob.Inc (POA).

Does PVsyst have any advantage in terms of accuracy? I mean: is 'Pérez transposition method' applied first and then the 3D model, shadows and horizon are applied or does the model itself also use the information from the geometry where the plant is located?

Glob.Inc. (POA) output of PVsyst is more accurate than GTI (POA) SolarGis?

[André Mermoud]

If SolarGIS uses the Perez model, it should have the same accuracy as PVsyst id the input data (Ghi and Dhi) are the same. 

Now you should be aware that the transposition model highly depends on the diffuse component. I don't know what is the diffuse model used by SolarGIS, but if you want to do a close comparison you should use the same input data (Ghi and Dhi) in hourly values.

In PVsyst, the horizon shading is taken into account before applying the transposition. Then the GlobInc (POA) is evaluated without any other perturbations.

The 3D irradiance models (shadings, IAM, etc) are applied on the GlobInc, DiffInc and AlbInc issued from the transposition.