GlobInc in collector plane is different for two versions at same project site

[bilalshahid148]

Hi,

Global incident in coll. plane is showing two different values in the loss diagram when all parameters are same using same meteo file, but the only difference is the size of PV modules (440 W and 400 W JA SOLAR) and the system size. There seems to an issue with simulations. Both simulation had same meteonorm files and collective plane are was almost similar, rather more in the simulation with lower GlobInc. Site location is also same, but there is the difference in loss diagram.

Please explain why this is happening, or what could be possible reasons.

Thanks a million!

[dtarin]

Is there terrain? Fixed tilt or tracker?

[bilalshahid148]

Fixed tilt; flat plain

[dtarin]

I cannot say, in my test (v6.84) there was no change to GlobInc. In a fixed tilt system on flat ground (no terrain), the only parameter that will affect GlobInc is system tilt if I recall correctly.

[bilalshahid148]

Thanks. We figured it out. Somehow, Hay model was selected as the transposition model. The simulation run with Perez had larger gain in GlobalInc. However, I am still confused as to which model is considered as industry standard globally. When should I switch to Hay model? Why is Perez preferred?

[dtarin]

Perez is the standard in industry. See additional posts here: https://forum.pvsyst.com/viewtopic.php?t=4596