How do I set up Bifacial module?

[st14m21]

I am facing the problem that I can't set the bifacial module when I use Nearshading.

Is it not possible to set the module when the orientation of the module is uneven?

Can someone please tell me what's going on?

[Bruno Wittmer]

The bifacial models currently implemented in PVsyst (V7.1.3) are based on an approximation that is valid for long and regular rows.

If you use a 3D drawing in 'Near Shadings', PVsyst will check that the PVsystem is based on a single orientation and rows with regular width and pitch (the row length may vary).

If there is too much variation in the pitch, you will get an error message, saying that the bifacial model cannot be used in this case. This is valid for fixed tilt rows as well as for single axis trackers.

This is also explained in the PVsyst help under:

Project design > Bifacial Systems > Bifacial system: 2-dimensional unlimited sheds

Project design > Bifacial Systems > Bifacial system: 2-dimensional unlimited trackers

If your installation is fixed tilt on an irregular terrain, this typically leads to several different orientations. You may consider gathering all tables in a single orientation group, by using the tool 'Manage Orientations' in the 3D editor of PVsyst. In this case, PVsyst will calculate the irradiance transposition by using a single average orientation, while the shadings will still be calculated with all detail of the drawing. If like this you can get a single orientation group, and the row pitch is regulear, the bifacial simulation becomes possible with PVsyst. You should use this approach only if the variations in terrain slope are small, it is not adapted for hills and steep slopes. You should keep in mind that this will calculate only an approximation of the bifacial contribution.