Advice on how to input recombination loss coefficients for non-amorphous tech

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Advice on how to input recombination loss coefficients for non-amorphous tech


I have been working with the recently implemented Mermoud LeJeune model in the SDK. It has been a great benefit to our modelling efforts. Thanks so much for providing this functionality.

I am still learning to use the model and have come across some questions that I hope will be useful to other people in the community who are also trying to learn about this new tool.

In particular, I have a question about the parameter 'mlm_D2MuTau', the coefficient for recombination losses. I have come across this parameter before in pvsyst, but only with amorphous technology, like first solar modules where D2MuTau is listed in the PAN files. I have never seen this term used in relation to non-amorphous technology.

Based on the definition of the coefficient I found in the pvsyst help manual (, I assumed the parameter was only related to thin film technology, and so left it at 0 when I ran my model for poly and mono-crystalline modules. However, I was surprised to see that my model's accuracy compared to pvsyst worsened dramatically when I did this, significantly over-predicting pvsyst's dc production estimates under otherwise identical modelling conditions.

Am I right in thinking that this parameter only applies to amorphous tech, or does it apply to crystalline tech as well, and if so, what are standard values for this parameter across different tech types such as mono, poly, and cis?

Out of curiosity, I ran my model with a 1.4 volt D2MuTau, pvsyst's recommended value for amorphous tech, and its accuracy improved dramatically. I am curious if this was a coincidence or the correct value for this parameter.

Thanks and Happy Holidays!

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