Simulation with multiple orientations, dome arrays and bifacial modules

[Jordi]

Hello, I am trying to simulate a fix structure ground mounted layout with multiple azimuths and tilt angles, with a combination of regular arrays and also dome arrays, with bifacial module and complex 3D terrain.

I have been able to run the simulation considering only monofacial modules and maximizing the orientation tolerance so I end up having only two orientations. However, when I define the modules as bifacial, Pvsyst does not allow me to run the computation with this type of system definition.

Is there any way to go around this issue and accurately simulate a system with such characteristics taking also into account the bifacial gain?

[Michele Oliosi]

At the moment PVsyst will allow to work in "bifacial mode" only when there is a single orientation. There is no way around it at the moment.
The best, if you can, is to split your system into several sub-systems (different variants) that have only a single well defined average orientation (if the topography is too complex, you can use the tolerance).
Now for domes it is difficult to split the system into two separate orientations (because usually they are connected to the same inverter) and averaging the orientation is usually not very realistic. However for domes, since not much light arrives on the backside of modules, I think you can approximate the situation by staying monofacial, i.e. not activating a bifacial model.

[Karl]

Hello, I'm having similar issues to the subject post and would like to know if this issue been resolved with the latest PVsyst versions?

I.E. will bifacial mode allow multiple configurations/tilts to be run within a single variant? I'm specifically running into this with bifacial mods in a dome configuration on a single inverter.

[Michele Oliosi]

It is partially solved in version 8, which should release (really) soon. You will be able to define separate bifacial models, one for each fixed tilt or tracker orientation. However, dome configurations are not yet covered by this update. We will work on it for a future minor release…

[FredrikRH]

Hello, I tried using version 8 with a bifacial system in multiple orientations. When I simulated it apparently only calculated the Global incident on ground for bifacial gain on my first orientation (see attached figure). In this case this sub-array was only 0.68 MWp compared to the full system of 28.76 MWp so the reduction in bifacial side production was quite noticeable. Is version 8 supposed to calculate bifacial gain for all orientations or will it only calculate for the first defined orientation? 

[Michele Oliosi]

@FredrikRH it should calculate the bifacial gain for all orientations. Could you send your project over at support@pvsyst.com ?
This would be extremely valuable to root out this bug.

[FredrikRH]

I have sent the project now, not sure where the error lies but it does not appear to be too big of a difference in total specific production between the two projects as it would seem from the detailed losses diagram. 

[Michele Oliosi]

Thank you ! This may or may not be the reason, but now it is important to go through all the sub-arrays in the system window, to make sure the different bifacial models are active and well-defined.
Indeed, there is a bifacial model per orientation now, to allow for different sets of bifacial parameters.