Shading losses

[Ricardo]

Dear PV SOL users & team,

I noticed that PV SOL reports show a figure for shading losses, can somebody please explain exactly what it means? In a project I am currently working on, this figure is 7,0%/year. However, the highest shading % displayed by a single module is 3,6% and of course, many modules show lower values, so it is obviously not an average as I initially thought.

 

Can somebody please explain what each figure (on individual modules and in the report) means and how they correlate? I would imagine that the figure on the module means the energy loss due to shading on it and likewise, the figure on the report is the overall energy loss due to shading, which can be higher than in any of the modules because of "shading mismatch" (that is, in an extreme case when one module is shaded 50% of the time and another module is shaded the other 50% of the time, the whole string is lost, so losses would be 100%). I would really appreciate if somebody could confirm this or if not, explain how it works.

 

Thanks in advance for your help!

[developer_mh]

Hi Ricardo,

another interesting question you ask there! The shading frequency in the 3D environment that is shown on every module (what your image is displaying) is the percentage of the annual reduction of the direct irradiance on the module under clear sky conditions. You can interpret this as the lowest possible loss that will occur due to the shadows on this module.

In the simulation there are a number of additional effects that will lessen the energy output, i.e. diffuse shading, mismatch of the electrical behaviour (as you described it) and so on. The percentage you get in the report is really the annual energy loss due to shading. There we compare the energy output of the PV plant without any shadows with the real one, so we include all various effects.

Hope that clarifies the matter, please let me know if not. Kind regards,

Martin

 

[Ricardo]

Hi Martin,

Perfectly clear, thanks a lot!!

[Infinitech]

Hello,
I would like refresh the topic.

Is the shading frequency in percentage on 3D simulation can be treated as the time of year when they are partly shaded?

[developer_mh]

Hi Infinitech,

no, it is really like this:

Quote

The shading frequency in the 3D environment that is shown on every module [...] is the percentage of the annual reduction of the direct irradiance on the module under clear sky conditions. You can interpret this as the lowest possible loss that will occur due to the shadows on this module.

The difference is, that it takes into account the height of the sun and its "power". If a shadow occurs at lower sun angles (morning or evening, or winter time), it has less impact on the overall percentage. If a shadow occurs at higher sun angles (noon, summer) it has high impact.

Hope that clarifies the matter a bit further, kind regards,

Martin

[Tom54]

Is there a design limitation in terms of production in case of shading?

[hotline_oh]

Dear Tom54,

Thank you for your inquiry.

Currently, only PV systems with up to 7,500 elevated or up to 10,000 roof-parallel modules can be simulated in the 3D environment. The maximum number of modules also depends on the number of shading 3D objects, such as trees, superstructures, module row formations, etc. 

Does this answer your question?