Near SHD According to module Strings

[Fredy]

Hello

I’m sorry for the question:

But is it normal to have both losses on the simulations?

-Near Shading Irradiance loss (= Linear shading) +

-Shading: Electrical loss acc. to strings

Shouldn't we have just 1 loss "Shading: Electrical loss acc. to strings", as it englobes the linear + the string that belongs to the shaded module?

 

 

Is it normal to have less production/PR with simulation according to module strings?

Of course the yellow area on the image above is bigger than the gray area.

- What I don’t understand is the linear shading is like a proportion of the shading area VS active area.

This should be like just the geometrical part of the shading?

- And the electrical effect should be when 1 module is shaded the whole string is inactive. But shouldn't that electrical effect be the only shading loss on the report?

It’s like we are adding 1 loss instead of changing the calculation method to the “according to the module string”.

It calculates geometrical + electrical?

Tell me if im wrong! Maybe I’m misunderstanding something?

How is this calculated?

Thanks in advance

Best regards

[Bruno Wittmer]

The linear shading loss is the fraction of irradiance that you loose due to shading. For the direct component this is just the fraction of the active surface that is shaded, but for diffuse and albedo it involves an integral over the entire hemisphere.

This loss means, that less light is reaching the modules.

The electrical loss caused by the mismatches due to shadows, is an additional effect that comes on top of this. If you do the simulation according to strings, you can define how much the impact of partial shading should be in a string. 100% means that a partially shaded string will produce no output, 50% that it will still generate half of the output, and so on. This is to account for the fact, that the production in a string will not drop to total zero, due to remaining diffuse irradiation.

If you use 100% for this factor, then your comment is right, it would not be necessary to calculate the linear shadings, since you loose all the string production. But for factors less than 100%, this mismatch(!) loss has to be applied on top of the irradiance loss, and this is why you have two separate entries in the loss diagram.

[Fredy]

yes i forgot to mention that i use 100% fraction for electrical effect.

and as you told me:

If you use 100% for this factor, then your comment is right, it would not be necessary to calculate the linear shadings, since you loose all the string production.

 

so this would be an additional loss that is already included in "Shading: Electrical loss acc. to strings"

Is there any away to remove the linear for simulations with 100% electrical effect?

because if we have 2 shading losses its like we have 2 shades on the top of each other.

[Bruno Wittmer]

The electrical shading losses account already for the shading losses, the loss is not computed twice.

The percentage losses in the loss diagram always refer to the preceding amount of energy.

You should read the loss diagram as percentages on top of each other, not as percentages of the total initially available energy.

Since shading loss and electrical effect are conceptually something different, and since logically they happen at different stages, it is reasonable to display them separately.