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"Shading loss according to module string"


josealjim
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Hi,

1-In terms of having a more accurate shading losses, Would be better to distribute the PV area in cell sub-modules (same bypass, 2-3 areas per module)? The bypassed area at the simulation will switch off when is shaded, leaving the rest of sub-modules producing, Would this sub-modules 3D configuration give problems with the final simulation?

2- Do I have to set then the fraction for electrical effect at 100%?

3- Additionally, Should I change the mismatch losses default parameter from 2.1% to 0%?

4- Can you please explain me the relation/differences between "shading ratio" at Electrical behavior tool and the "Fraction for electrical effect" at the 3D simulation?

Thank you in advance

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Some answers, but you should also refer to the help.

1. In a row arrangement, when the bottom cell line is shaded, the concerned string doesn't produce any electricity anymore. The by-pass diodes don't help in this case. As soon as 1/3 of the sub-modules (modules parts protected by a diode) of a string are shaded, the string's voltage is not sufficient to participate to the array power.

You can only have a little recovery if the string is alone on the MPPT input, but it may also be below the Vmpp threshold of the inverter.

2. For this reason the "Fraction for electrical effect" should indeed be set to 100% with shed arrangement.

3. The mismatch loss parameter has nothing to do with the shadings effects (see How to define the Mismatch Loss parameter?)

4. See our FAQ What is the "Shading loss according to module strings", and What is the "Fraction for electrical effect".

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Dear Mr. Mermoud,

I have read the help information and the topics posted but they didn't clarify my doubts, sorry for my ignorance.

You say that as soon as 1/3 of the sub-modules of a string are shaded, the whole string does not participate to the array power, but using the module layout with the version 5 I get different information. The configuration I want to make is 4 modules in a row for one MPPT.

-1 row with every bottom sub-module fully shaded (attached):

Linear shading on global= 14.2%

Additional electrical loss= 20.9%

Total= 35%

-1 row with one module with 3 sub-modules partially shaded (attached):

Linear shading on global= 8.9%

Additional electrical loss= 17.4%

Total= 26.3%

-1 row with bottom sub-modules partially shaded (attached):

Linear shading on global= 1.8%

Additional electrical loss= 7%

Total= 8.7%

Could you please help me to understand why it is still producing when bigger area than 1/3 of the sub-modules is shaded?

Thank you in advance.

Could upload some examples of shading calculation with PVsyst?

shading.rar

shading

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