Shading with "module layout" versus "According to module strings"

[tommm]

Hi everybody !

I'm use to work only with the "partitioning" tool in 3D scene (+ the "According to module strings" option)  and a colleague ask me why I don't use the "module layout" tool for electric calculation (I never use this one !)

So I try the module layout tool and I find some inexplicable difference in result. I have simplify the problem with a very simple simulation : 1 string of 26 modules with 1 azimuth/tilt and an obstacle shading approximatly 1 module everytime (very theoretical problem !). With this case, I expect a very low production because of the entirely part of the string is shaded.
Sim 1 : using of "Partition" in Near shadings 3D scene and the "According to module strings" option and 100% electrical losses. 1 rectangle in with and 3 in height because my module is a 3 bypass diod.
Sim 2 : using of "Detailed electrical calculation (acc. to module layout)"
The module is a Twin half cells (JKM-420N-54HL4R-BDV).

Result : PR Sim1= 0.387 and PR Sim2 = 0.797
Module layout seems to not take into account the electrical losses on the whole string.

I have an explanation but I'm not sure : does the Twin half cells let the string produce even if a whole part is shadowed ?

Thank you for your help !

Br

[André Mermoud]

First observe that the option "Electrical shadings according to module strings is an approximation, under strong hypothesis. This is valid especially for sheds-arrangements, where you have the shade of the previous row on the full length of the row.

This is not valid for specific shadings like yours. In this case only the "Module Layout" can give a reasonable evaluation of the electrical shading effect. This is the reason why you have a parameter "Fraction for electrical effect": this should be 100% for sheds, but allows to correct the result of the irregular shading objects. The only way of evaluating this parameter is to perform the "Module Layout" calculation, and adjust if for getting the same electrical shading loss result.

Please carefully read the help  "Project design > Shadings > Electrical shadings: partition model". In the graph of this page, when you are shading one only module you are at the very beginning of the graph.

Now in the option "Calculation by module strings", when defining a partition with your system, the rectangle should be the  rectange corresponding to the full string, i.e. the width of the module by the number of modules. You should not define 3 rectangles because there are 3 submodules.

With Twin half-cut cells modules, when these are in landscape they behave exactly as usual modules, and when these are in portrait, you should indeed define 2 rectangles, one for the lower half and one for the upper half of the module.