Hi,

I'm designing a smaller ground based project and are currently investigating the option of bifacial vs monofacial modules. But what I don't understand is how the PR value is calculated for bifacial systems. I noticed that the PR is less for some of the bifacial systems compared to identical monofacial systems. 

When calculating the PR manually I use this equation: PR  = ("PV energy (AC) minus standby use") / ("Global Radiation at the Module" - "Reflection on the Module Interface") * module area * module efficiency )) 

But it doesn't match the PR when calculated manually for bifacial systems compared to what is presented in the report. How can I calculate the PR manually for Bifacial systems?

 

Hope to hear from you soon,
Douglas

Hi Douglas,

please excuse the late answer. I just checked the calculation of the PR of bifacial modules in PV*SOL and couldn't find an error. Could you send the project where the manually calculated PR and the PR from PV*SOL differ? Just a small hint (but I don't think this leads to the problem): The brackets in your formula should be replaced like so:

PR  = ("PV energy (AC) minus standby use") / (("Global Radiation at the Module" - "Reflection on the Module Interface") * module area * module efficiency ) 

Kind regards,

Martin

Hi Douglas and Martin

I am trying to obtain the same PR value as it appears on the second page of the report

by calculating it with the data obtained by the minute simulation, I am usig the ecuation Martin wrote down but it is still not the same.

is not the reflection on the module interface included in Global Radiation at the module?.

*module area* module efficiency is the same that kWp, or the software change the module efficiency?.

I want to calculate the monthly PR, I have already seen the way to obtain it for each inverter. does this way include the soiling/ the reflection /the shading, how would be the ecuation of this PR.?

 

Kind regards

 

 

 

Okay, I have found my mistake, the reason was I didnt subtrac the reflection on the module, I was adding it. because I thought that being a negative value you should add it.

 

I suppose that the reflection is not included in the PR therefore?.

 

Kind regards.