doubts regarding pvlib run from effective irradiance

[Gaurang Chhapia]

Hello community,

I just have a question out of curiosity, in run_model_from_effective_irradiance what is total_abs_back and total_inc_back. what is the difference between them. I also have another question, how do you calculate the available irradiance between rows of pv panels.

[kevina...@gmail.com]

total_abs_back and total_inc_back are pvfactors names, so I assume you are talking about the code in this example: https://pvlib-python.readthedocs.io/en/stable/gallery/bifacial/plot_bifi_model_mc.html

"abs" and "inc" stand for "absorbed" and "incident", respectively.  The difference is that "abs" includes the effect of IAM, and so will be somewhat reduced relative to "inc".

Kevin

[salazar...@gmail.com]

Hi everyone, hope you are doing well.

I understand that the effective bifacial irradiance (i.e., total_abs_front + (total_abs_back * bifaciality)) already takes into account the derating by IAM since the absorbed is used.

Is it correct to additionally derate the effective bifacial irradiance with the spectral mismatch modifier (something like: smm * (total_abs_front + (total_abs_back * bifaciality)))?

Thanks in advance!

Nelson A. Salazar Peña

[kevina...@gmail.com]

Hello Nelson,

Conceptually, sure it makes sense to account for spectral mismatch when calculating effective bifacial irradiance.  The tricky part is that the different in-place irradiance components may have substantially different spectral mismatch modifiers.  For example, consider how the color of the ground surface will affect the spectral mismatch modifier for the rear-side irradiance.  The usual SMM models (including the ones available in pvlib) are based on atmospheric properties and in general aren't intended for adjusting the rear-side irradiance component.

Kevin