Correctly modeling string partitions with power optimizers

[lmackay]

Hi all,

I'm looking for some feedback on the best approach when modeling a shade scene "according to module strings" for systems with Solaredge inverters and optimizers.  Considering how optimizers deal with shade, is it most realistic to model the string partition as 2 modules in alignment with the series pair connected to the optimizer, or as the larger partition of the total string of optimizers?  I suspect it's the prior, but I wonder if that is double-counting the optimizer benefits?  Is PVSYST already accounting for the optimizer behavior in the other calculations?  How do you all handle these types of systems?  Thanks!

[André Mermoud]

The  shadings calculation "According to strings" is applied to an array connected to one MPPT.  With optimizers, the MPPT input is one (or possibly 2) modules.

Therefore each rectangle should represent  the set of modules connected to one optimizer.

NB: The ModuleLayout option is also useable for the calculation of the electrical shading loss with optimizers.

 

 

[stask]

When we simulate SolarEdge inverters and optimizers (and we do it a lot here in Israel), we always use the Module Layout tool. 

Its also written in the help section regarding SolarEdge architecture :

-the electrical effect has to be evaluated using the "Module Layout" tool, which is adapted for SolarEdge optimizers.

-the shadings option "according to module strings", as usually used with rectangle-strings corresponding to the modules of one optimizer input, is not really suited. It will give under-evaluated Electrical Shading loss.

You can actually also use the Linear Shading option as there are practically no strings in a SolarEdge system (well actually its probably more correct to say that in SE systems we have either 1- or 2-panel string lengths). I havent seen almost no difference in energy production if use Linear Shading option or Module Layout. But I may be wrong here.