Near Shading calculation problems

[Iso]

I am using version 6.6.2 and observe the following problems:

1)

When I make a "Near Shading" model with 3 PVs - each split into 3 module string, I get to a point where I can generate the two shading factor tables: 1 table for the "linear case" , and the other tables for the "according to module strings" case. However in the actual simulation, the shading loss end up with the same value for the two cases, although the tables are quite different (and look correct). So it seems that the simulations are carried out only with the table for the "linear" shading case.

2) The button for "module layout" only appears when I use Grid Layout - not for the "stand alone" project case. Does this mean that the corresponding feature only works for Grid connected cases ?

[André Mermoud]

The "linear" shading loss is the result when using the first table.

The second table is used for computing the Electrical loss (accounted in the Array losses), which results basically of a difference between the two tables.

The Module layout tool - which is closely related to the inverter behavior - is indeed not available for Stand-alone systems in the present time.

[Iso]

Ok - I hope that the module layout part will come also for stand-alone systems soon.

However, I have another related issue: When I do a simulation in Grid-connected systems, and compare "module layout" results with "according to module string" results, I get a much smaller loss for the "according to module strings" case, than for "module layout". I have of course made sure that the actual module layout is the same in both cases (the module partitioning in near shading set-up and the module layout).

I would expect that the "according to module strings" case would be an upper bound, since a partly shaded string here is counting for a full "loss of the whole string". I am using "100% fraction for electrical effect".

When I look at the shading fraction table for "module string case" it looks correct, but when I output the shading factors to a file, they appear strange, and seems to be of a size that indeed will result in a loss which is too low.

Can you please explain - thanks ?

regards

Iso

[André Mermoud]

This is because you have not defined the "rectangles" representing a string correctly. You have defined one rectangle as one submodule.

In the option "According to module strings", one rectangle should correspond to one full string.