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Simulation with non-coherent results
https://forum.pvsyst.com/viewtopic.php?f=25&t=3728
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Author:  Manuelsl [ Thu Sep 13, 2018 9:02 am ]
Post subject:  Simulation with non-coherent results

Good morning Sir, I have obtained strange results when performing a simulation of a grid connected PV plant.
The plant has 6 sub-arrays with the same inverter, the same scene (number and type of tracker) and the same array design.

One of the variants includes 5 sub-arrays with Risen modules RSM72-6-365M (PERC) each + 1 sub-array with Risen RSM72-6-370M (PERC).
Another variant has 4 sub-arrays with Risen modules RSM72-6-365M (PERC)+ 2 sub-arrays with RSM72-6-370M (PERC).
The second variant has higher arrays global power, which should give higher production and PR, however the results are opposite to those expected.
The detailed loss parameters are the same in both variants.

The .pan files used in the simulation are those provided by the manufacturer

Could you inform me why these results are obtained?

Thanks
Manuel

Author:  AndrĂ© Mermoud [ Wed Oct 17, 2018 11:37 pm ]
Post subject:  Re: Simulation with non-coherent results

The problem is perhaps what you are expecting...

If the yield is higher, this doesn't mean that the PR is higher, as it is normalized to the installed PNom. If the PV modules have rigorously identical performances (same Low-light behavior, same temperature coefficient, same IAM), the PR should be identical.

Now you don't tell us which level of differences you observe (in percentage).
There may be a discrepancy:

- If you have inverter overload: in this case the loss will be higher for the second system, and therefore the PR will be lower.
- As explained in the FAQ Why is the Pmpp of my modules different from the specified value?, the Imp*Vmp at STC may be different from the PNom of the module. This will induce a distortion of the PR.

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