Different POA bifaciality gain % for Norway and USA

Hi, can someone help me to find the reason for the below pictures? I simulated parametric runs for different azimuths and two locations. The bifaciality gain is not similar. 

Hi Ronald,

I would expect the array orientation to affect the bifaciality gain because it affects the size and timing of shadows between rows of modules in the array.

Best regards,
Paul.

Thanks for the quick reply. However, why there is a large gain between east and west for Skjetelien, Norway and there is no gain for Phoeniz, USA: I know that there will some gain difference for Norway but this is very large right?

Hi Ronald,

Could you attach the .sam file and weather files you are using for this comparison?

Best regards,
Paul.

Hi Ronald,

I think these results have to do with the data in your weather file.

Here are results from a parametric simulation I ran using the "S49 BiFa" case in your file with a weather file for a location in Alaska with a similar latitude to your weather file. It shows a similar bifacial gain vs tilt angle for azimuth = 90 and azimuth = 270:



The results with your EPW file confirm your observation below:



When I compare the DNI data for your file with the Alaska file, I see that the DNI data shows a tendency to be higher in the morning hours. I think that is consistent with the results showing that the irradiance on the back side of a west-facing array would increase more with the array tilt angle than for an east-facing array:



The Alaska data does not have that pattern:



Best regards,
Paul.