Bifacial modeling with shading scene

[Pranav Maheshwari]

Hi,

I want to simulate bifacial modules in a rooftop space, with shading elements

 

So in order to simulate the shading loss, 3D shading scene is required.

I also understand that bifacial modelling can only be done either using an unlimited sheds or unlimited trackers (2D geometries) as it computes view factors accordingly. Although my case is very different to unlimited shed model, but to approximate, I want to enter the pitch as per approx. roof space available on either sides of the PV table.

So I want to enter the pitch and shed total width manually. Shed total width can be exact based on my table size, and for pitch I can enter an approx. number based on the space available on either sides of PV table. But it does not allow me to change these values manually (even if I change these numbers, it automatically changes them back)

 

How do I fix this. So that I can estimate approx. bifacial gain as well as shading losses correctly.

 

One temporary method is I do multiple simulations:

• One without bifacial modelling with shading scene: using this I will estimate the shading losses
• Other using bifacial modelling without shading scene and considering unlimited sheds, where I can put the approx. pitch and get an approx. bifacial gain

I imagine that the actual bifacial gain will be actually more (for my case), than using an unlimited shed approx.

 

Please guide!

[Michele Oliosi]

Hi

4 hours ago, Pranav Maheshwari said:

I also understand that bifacial modelling can only be done either using an unlimited sheds or unlimited trackers (2D geometries)

Actually, this is a misconception shared among many users. You can simulate with the bifacial model and a 3D shading scene ! However, there are conditions on the shading scene for this to work https://www.pvsyst.com/help/bifacial-conditions.htm

The main issue in your case is that you don't have multiple rows of tables, but just a single row. Besides, the tables are not the same width. This will prevent from using the bifacial model jointly with the 3D scene. I would suggest the following:

• Make a variant without the small table.
• Replace the other 11 modules by a single 6 by 2 table.
• Duplicate the whole scene and place the copy far away to the northwest. This will mimic a second row and trick PVsyst to let you use the bifacial model. But because the second table is so far away, they won't affect each other.
• You should use the shading mode “according to module strings”. Because the number of modules is not the original one, using the detailed electrical calculation is not possible.

[Pranav Maheshwari]

Understood @Michele Oliosi

But can I do as per the following method using multiple simulations:

• First simulation: without bifacial modelling with shading scene: using this I will estimate the shading losses
• Second simulation: using bifacial modelling considering unlimited sheds without shading scene: where I can put the approx. pitch and get an approx. bifacial gain

I imagine that the actual bifacial gain will be actually more (for my case), than using an unlimited shed approx

 

Please confirm if the above approach can also be used?

[Michele Oliosi]

Yes, can follow the method. I would suggest combining your idea with my previous comment, i.e., using the 3D scene variant, but choosing only a single orientation. This would be the second simulation. It is likely a bit more precise than the simulation with unlimited sheds.