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PR value greater than 1


yovandeer

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Is this a vertical bifacial system? I believe the PR calculation you see does not take into account rear-side irradiance in the PR calculation, and only the front-side POA irradiation. Since your bifacial gain is so high and your POA (GlobInc) is negative, this would lead to a PR greater than one. Try manually calculating PR to include the rear-side irradiance, and see what your results are.
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It is due to the orientation. PVsyst calculates POA as if it is a monofacial module first. A monofacial module oriented vertically 90 degrees in the EW direction would not receive direct light when the sun is behind the module, which is essentially for half the day. A module flat on the ground at 0 tilt receives no transposition gain, POA = GHI (roughly speaking). When you tilt that module vertically to 90 degrees in the EW direction, it's halved. In your waterfall diagram, GlobInc is -51%.
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I think more information is needed to understand. What does your meteorological instrument set-up look like, where are the sensors and what are they measuring? What data was imported into PVsyst?

Also, unrelated to you PR question, I noticed you are modeling degradation at year 20 which I am not sure you want to be doing, but I could use some more information to better understand. Feel free to shoot me a pm if you'd like to discuss.

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Hi

I'm sorry for my late answer. I was waiting for a respond of my collegue (who measured all the data) to give you some more info about the measurements setup. I hope to receive the info soon.

Thank you for noticing but why is it not smart to module degradation at year 20?

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oh okay thank you!

And to answer your question about the measurement setup:

we measure the air temperature, wind speed, GHI, POA from both sides of the solar panel and the module temperature.

The POA instrument is directly in the plane of the panels and the temperature sensors are glued to the panels.

Temperature , wind and GHI are simply measured in the field.

GHI and POA are given in W/m².

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