Is the module frame considered in the shading analysis?

[Niklas]

Hi all,

I got a rather specific question regarding the shading analysis so this might not be for everyone. During the design process of a solar facade our architect got the idea to maybe tilt individual modules to get a more interesting looking facade. Now I want to investigate the influence of shadows due to different tilt angles of nearby modules on the yield using the shade frequency tool (see following picture). While trying different tilt angles, a question arose for me. How is the inactive area (e.g. the module frame) of a solar module taken into account when calculating power losses due to small shadows on the edge of a module?

PV modules made for facade-integration are often frameless and manufactures of those modules therefore use the minimal frame thickness parameter of 1 mm in the PV*SOL database. In reality a small inactive edge of usually 10 to 20 mm still exists. Let's say a shadow is hitting this inactive edge without reaching the solar active part of the module. Would PV*SOL still calculate the module as partly shaded? Of course this example is a quite theoretical question. In my specific case I wonder, whether the small but strong shading on the edge of some modules is weighting heavier in the simulation than it does in reality. A shadow on the inactive edge area of a solar module would in reality not influence the yield at all. I would love to get some insight into how PV*SOL handles this!

Also, while trying some things in a different project, I got a very interesting result for the "yield reduction due to shading" in the simulation results tab. How is PV*SOL allowing a negative yield reduction due to shading? So, a negative yield reduction would be a "gain in yield due to shading" ... That doesn't sound right to me. Did I encounter an error? I always use the latest version of PV*SOL. If needed, I can certainly provide the file since it was only a test project anyway.

Many thanks in advance!

Niklas

[developer_mo]

Hi Niklas,

thanks for your question and report and sorry for the late reply.

On 3/15/2024 at 5:01 PM, Niklas said:

How is the inactive area (e.g. the module frame) of a solar module taken into account when calculating power losses due to small shadows on the edge of a module?

My assumption is that shading that only affects the inactive areas will not lead to a reduction in yield. However, this is only an assumption. I have emailed the respective developer and will update my answer as soon as I have more information.

On 3/15/2024 at 5:01 PM, Niklas said:

How is PV*SOL allowing a negative yield reduction due to shading? So, a negative yield reduction would be a "gain in yield due to shading" ... That doesn't sound right to me.

That's right, a negative yield reduction due to shading should not exist, even if it is very small. But as you said, it's best if you share or send me your project file, then I can hopefully find out more precisely what the problem is in this case.

Kind regards

Mikio

[Niklas]

Hi Mikio,

thanks for your answer. I am looking forward to your edit regarding the effects on the inactive areas.

For the negative yield reduction, I attached my test-file below.

Kind regards

Niklas

negative_yield_losses.pvprj

[developer_mo]

Hi Niklas,

thanks for the project file.

I now know how the yield reduction can be influenced, that it can be slightly negative in marginal cases. Two factors contribute to this: firstly, that the outlet air pipe is relatively small and secondly, that it is located on a roof overhang.

To avoid this behavior, you could change the roof so that it no longer has any overhangs and is longer by the corresponding length. The reduction in yield should then be 0.1 % instead of -0.1 %.

Since it only occurs at very low values of yield reduction (if the outlet air pipe is slightly higher, the yield reduction behaves as expected) and the simulation is almost unaffected by this, the bug will probably be prioritized low. Nevertheless, many thanks for the report and I will send it to the developer for this area.

I also asked whether PV*SOL calculates a yield reduction due to shading if the shadow only falls on the edge of a module (i.e. in an area without photocells). The answer is no. Only the area minus the module edge and module frame is used to calculate the yield.

Kind regards and good luck with your project!

Mikio