Generation for E-W vs S facing modules

[Aparna]

Hello everyone,

This query is based on an observation on a rooftop plant installed at our office. We have a section that is comprised of E-W facing sheds at an inclination of 10 degrees and a section which has S facing sheds at an inclination of 10 degrees.

It has been observed that the inverter connected to the E-W facing sheds give a higher energy output than the inverter connected to the S facing sheds, throughout the year and also, this difference in energy generation is highest in the summer months and reduces in the winter months.

We have also measured the GHI for the location using a pyranometer. The tilt radiations were then generated in PVsyst. It is seen that the radiation on the tilted plane of the south facing sheds is higher than that on the E-W facing sheds.

We are trying to analyse the possible explanations behind this observation. Has anyone else come across a similar situation ? Could anyone offer a reasoning ?

Thank you.

[unilhexio]

Hi,

Are both systems identical? Same module and inverter manufacturers, shadings scenes, row distance, etc...

It may also be related to wind expossure, module degradation, mismatch losses...

Regards!

[Aparna]

Hi Unilhexio,

Yes, the systems use modules and inverter of the same model and manufacturer. Both systems have been designed and installed devoid of any shadings.

Could you please explain how the wind exposure can affect the module performance?

Thanks,

Aparna

[unilhexio]

Hi, Aparna,

The exposure to wind has a cooling effect depending on the mounting of the PV modules, increasing the yield.

You can read more accurate information about this on PVsyst help ("Array thermal losses").

Regards.

[cnrikio]

Personally speaking, i do not think the wind exposure could result in such a big difference. I have done such a comparison, and south facing array still get a higher yield.

Aparna, which kind of module technology was used, c-si or a-si? Thin film modules may have a better power yield since the beter low light performance.