IRREGULAR PITCH: HOW TO IMPLEMENT THE BIFACIAL CARACTERISTICS

[C. Amorevole]

I am working at a fixed PV plant characterised by an irregular terrain slope and bifacial modules. In order to choose the exact projects settings for the plant, I decided to divide the terrain slopes into 2 main categories and define the correct pitch for each of them: eventually I obtained 2 areas with same projects setting in each of them (same pitch, same tilt, ecc). 

Importing the plant in the 3d scenary I faced this screen:

this is the first problem: I tried to fill the group "partial shadings selection" but I couldn't select exactly the structures I need, unless selecting one by one in the "list and management of objects" in the "partial shadings group" in 3d scenary:

I tried to avoid the problem, modifying the hidden parameters and enlarging the "pitch rms limit" from 0,1 to 1 meter. I would understand if this adjustment may influence only in near shadings 3d calculation (and this means that I would correctly evaluate the shadings losses) or it may affects also on the simulation. Reading the orientation settings, it seems that it considers only one orientation (fixed tilted palne). It may be quite a big approximation.

Do you know a different/better solution?

[Michele Oliosi]

Hi,
Thank you for the different comments.

First of all, I am not sure that "partial shadings group" will help in your case. Indeed, it allows to take calculate the frontside shading factors using only part of the tables, but has no impact on system or orientation. If there are two nominal orientations in your scene, even though you use the partial shadings group, in "Orientation" there will still be two orientations. If I'm not mistaken the pitch used by the bifacial is still the average of the whole scene as well, not only the partial shadings group.

Second, the bifacial model is limited in its use to a single orientation in "Orientations". If you want to avoid the issue of using the average orientation, you will have to do two different variants, each with its shading scene containing only the objects from group 1 or group 2, respectively. In future (long term) major version v8 we will link the bifacial model to the orientation so you don't need to split in two variants. But this is still in development.

Changing the pitch rms limit serves the purpose of bypassing the error message in PVsyst and proceed by using the average pitch even though your scene has several pitches. So there is no direct effect on the simulation results.

Again thanks for the comments and sorry for the complications for this kind of scenes. Your post will definitely help making PVsyst better in the future.