Bifacial in an east-west configuration

[J. Behrschmidt]

We want to simulate a plant with modules oriented east-west (dome) and south. Our customer want to use bifacial modules. Now we had the problem to guess, if we have a bifacial gain for the modules of the east-west (dome) part. We tryed to simulate it separately with modules in rows first for west. To consider the shadings of the east oriented modules we exchanged it with quaders as shading objects. Now we see a bifacial gain of 5%. For us this is not plausibel, especially we compare it to the south oriented part, where we have a gain of 2%. It seems for us that the shading objects are not considered for the calculation of the bifacial gain, even when shadow casting is enabled. 

Because the results are not trustable we will set the bifacial gain to zero, even we belief that a small gain should be possible, because the rows are short and the gable are not shaded.

Does someone have experience with bifacial modules in east west configurations?

[Michele Oliosi]

From what you say about the system, especially it being an east west dome system it is likely that the bifacial gain will be low. However someone with more field experience should formulate a better answer here.

From the PVsyst side it is as you say: the bifacial model and hence the backside irradiance do not take into account the shading scene for the shadings, only the interrow spacing, size of the tables, and the orientation are used. Therefore 5% is likely an overestimation.