Linear shade loss model - continuation of pr 1725

[echedey-ls]

• Closes Add linear shade loss model for thin film #1690
• Substitutes Linear shade gh1690 #1725 (originally from @mikofski )
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• Tests added
• Updates entries in docs/sphinx/source/reference for API changes.
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• New code is fully documented. Includes numpydoc compliant docstrings, examples, and comments where necessary.
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Addresses the linear thin film module losses.

Comment from @kandersolar at #1962:

you are saying that we need a substantive reference that says linear power loss models are valid for thin film modules. Is that right?

What I'd really like to reference is a paper that deals with specifically the equation implemented in this PR: power_loss_fraction = shaded_fraction1d * (1 - diffuse_fraction).

@mikofski do you have a reference for that or should I change to irradiance losses and a SAM reference?

Wait for #1962 to be merged before this one so the docstring makes sense.

[mikofski]

I found this by googling:
https://energy.sandia.gov/wp-content/gallery/uploads/26-Littmann-Tracking-and-Diffuse-Shading.pdf0_.pdf

It’s for series 4 but explains why linear shade for orientation perpendicular to cells

[echedey-ls]

I found this by googling:
https://energy.sandia.gov/wp-content/gallery/uploads/26-Littmann-Tracking-and-Diffuse-Shading.pdf0_.pdf
It’s for series 4 but explains why linear shade for orientation perpendicular to cells

I don't really get to see where it explains the shade is perpendicular to the cells. I mean, I see the statement but not the reasoning.

I would prefer some other reference, although I'll stick to that one. I will update the PR by the end of the week.

[mikofski]

Maybe if you combine this reference with the FirstSolar series 4 user guide. The point is the cells are long and thin and strung in series from side to side. The user guide explains that they should only be oriented so that the cells extend from bottom to top, not left to right or damage will occur. There is also a series 6/7 user guide.

[echedey-ls]

Thanks for that insightful manual. I like how the docstring is turning out!

These references don't have the model equation nor address what the model modifies (power yield or irradiance). I think it doesn't matter as long as we find some other source that deals with the model eventually. Maybe some code snippet on the public domain under First Solar authorship?

[echedey-ls]

I have the feeling that the reference still is an issue. If you maintainers think so, do you think the same reference as #2063 and #2070 , equation (3), is a sustainable reference?

https://www.sciencedirect.com/science/article/abs/pii/S092702481000454X

Pro: it compares the results in Table 2 and Fig. 4.
Cons: it is compared for non-monolithic modules

EDIT: content

[mikofski]

Hi @echedey-ls that reference isn’t really valid for firstsolar modules because firstsolar don’t use bypass diodes and the power loss isn’t exactly the same as the fraction of direct beam shaded, because there is still diffuse sky and ground. I think the best references are Kevin’s & Adam’s paper and the poster from PVPMC 2023 (https://pvpmc.sandia.gov/download/5381/?tmstv=1719027091). Saying the loss is linear is just industry jargon four saying there is no electrical mismatch due to shade, so the only loss is the linear decrease in direct beam.