Module temp coefficients

[electro7]

To confirm, when the negative Voc temp efficient is a lower number, that means the module loses less voltage as the ambient (and/or cell temperature) increases, correct?

I see in some modules that the Voc and the Pmax temp coefficients don't correspond necessarily, and I was wondering why? Some modules have a low voltage temp coefficient but a higher % loss on the power temp coefficient than other modules that have a higher voltage temp coefficient lose (if that makes sense). Is it the cell technology and resistance to current flow within the module?



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[ggunn]

To confirm, when the negative Voc temp efficient is a lower number, that means the module loses less voltage as the ambient (and/or cell temperature) increases, correct?

Yes.

I see in some modules that the Voc and the Pmax temp coefficients don't correspond necessarily, and I was wondering why? Some modules have a low voltage temp coefficient but a higher % loss on the power temp coefficient than other modules that have a higher voltage temp coefficient lose (if that makes sense). Is it the cell technology and resistance to current flow within the module?

The current differential per degree C is so much smaller that that of voltage that it is usually ignored in the design process.

 

[electro7]

But if a module power coefficient is -.25% and another is -.33% wouldn't that mean the module with the lower (-.25%) produce more power in higher temperatures?

Which brings up the question about the rated efficiency for me. I understand the % efficiency rating is at STC, 25°C. With a module that has a higher efficiency but also a higher Voc temp coefficient (and/or higher power coefficient), does that mean that module won't perform as well in high heat conditions than a module with a slightly lower efficiency rating but lower temp coefficients?

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[ggunn]

But if a module power coefficient is -.25% and another is -.33% wouldn't that mean the module with the lower (-.25%) produce more power in higher temperatures?

Yes, if their STC ratings are the same.

Which brings up the question about the rated efficiency for me. I understand the % efficiency rating is at STC, 25°C. With a module that has a higher efficiency but also a higher Voc temp coefficient (and/or higher power coefficient), does that mean that module won't perform as well in high heat conditions than a module with a slightly lower efficiency rating but lower temp coefficients?

Maybe, but it's a bit of a balancing act when the lower efficiency module's output would surpass that of the higher efficiency module, and that's assuming all other factors are equal, which they never are.

In the real world, it's usually the case that the price per Watt for the modules overrides these considerations.

 

[electro7]

Yes, if their STC ratings are the same.

Maybe, but it's a bit of a balancing act when the lower efficiency module's output would surpass that of the higher efficiency module, and that's assuming all other factors are equal, which they never are.

In the real world, it's usually the case that the price per Watt for the modules overrides these considerations.

Right, gotcha. Thanks, ggunn!

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