Stringing limitations

[jasperpak]

Hello,

It seems that with each new version of PVsyst there are significantly more stringing limitations that seem either buggy or unnecessarily restricting, specifically with the SolarEdge optimizer strings. Maybe there is something I'm missing, but layouts that I could easily accomplish earlier this year are now impossible to recreate and the only option I see is to revert back to older versions. Any help is much appreciated!

The main issue has been small windows of allowed string sizes for optimizers, preventing me from creating systems which are clearly possible when looking directly at the specs of the equipment. While I can see that disallowing certain string sizes could help avoid errors in general, it also provides significantly less flexibility, particularly when designing multi-orientation rooftop designs. A suggestion to the software would be to allow more detailed mixed orientation inputs to account for the decreased flexibility in string sizing. This is one of the main benefits of using the optimizers and it seems like the importance of this function has been made impossible to model using PVsyst.

I have also noticed that for certain system designs, PVsyst will not allow me to input an even number of optimizers. I.e. when I select to have 12 in series it will say the range is 8-11, but when I increase to 13 optimizers in series, it says that the range is 8-13 and allows it; and so on for 14, 15 etc... I have included snapshots below:

 

 

Does anyone know why this happens? Any suggestions for work arounds would be awesome!

[André Mermoud]

You are speaking about SolarEdge technology.

Up to version 6.64, the treatment of SolarEdge systems was based on directives of SolarEdge edicted in 2010. SolarEdge had not updated these constraints during several years.

From version 6.64, we have completely rewritten the treatment of the SolarEdge architecture. The rules specified by SolarEdge are extremely complex. They are different for each association (Optimizer - Inverters), and for US or rest of the world devices. They are not applicable to old devices, which still have some constraints of the old treatment.

It appeared that the previous treatment could not meet the new requirements, and may lead to unaccuracies in the simulation, due to insufficience in the parameters description. We had to completely restructure this behavior.

Now there may still be some youth problems, like the one you mention during the sizing process. We try to correct them.

NB: mixing orientations in a same string is indeed allowed with the SolarEdge technology. But in accordance with SolarEdge, we have given up developing this at the moment, as this leads to very big complication in the structure of PVsyst.