Bifacial model not working for single tables in PVsyst 8

[Miguel G]

Hello,

When PVsyst 8 was released I was able to run a complex carport PV simulation using the bifacial model (see attached report).

It consists of 2 orientations but actually I defined 5 orientations because although the southern carports share the same orientations, their table widths are different.

 

I took advantage of the new bifacial model features of PVsyst 8 in regards to the pitch and number of rows defined by the user for the cases when you don't have an unlimited-sheds type of array.

However, now with 8.0.13 version when I try to run again the simulation (because I need to get an 8760 file), I'm not able to run the simulation with the bifacial model anymore. I got the following errors for all orientations except for orientation #1.

 

I don't understand why I'm getting this pushback, when we haven't modified anything to the original PRJ. 

 

In fact, when I try to modify the bifacial model values (such as tilt, pitch, width, and so on) for those orientations, PVsyst doesn't save that information and applies a generic 25° tilt a 0° azimuth, when in reality all arrays have a 5° tilt in System and 3D definitions. See an example for orientation #2 (-41.5° azimuth).

 

I would really appreciate any advice on this issue.

Thanks!

 

MoCo 6th District Police Station V6.VC0-Report.pdf

[Michele Oliosi]

Hi,

It was indeed possible to define situations with only a single row + 3D scene + bifacial model in previous patches. However, this was not the intended behavior and was a possibility that was exposed by a bug. We would not be able to guarantee that the calculations were properly handled in this situation. 

We have recently corrected some issues in terms of number of rows, and that has had the effect that the above unwanted exposure was corrected as well. Currently, the calculation with a single row in an orientation (such as your orientations 2, 3, 4, and 5) can only natively be realized with an unlimited orientation.

There are therefore two workarounds:

1. Model orientations 2-5 as unlimited orientations with one row.
2. Duplicate the 3D tables from orientations 2-5 and any objects that may shade them. The duplicates should be placed far enough on the scene so that there are no unwanted interactions. In this way, PVsyst recognizes two rows instead of one. Since they are sufficiently spaced, mutual shading effects are negligible.
   • You may need to alter the following advanced parameters (Home window > Settings > Edit advanced parameters) to avoid some problems with a larger scene than the modules defined in the system window
     
   • This solution does not work with Module Layout definitions (because these necessitate a perfect match between 3D scene and system)

Please note that supporting 1 row bifacial orientations is in our internal roadmap, and I will rebound on your request with discsssions to see whether we can anticipate this feature a little.