Recreating PVsyst runs with same MWh output

[Renewables]

Hi,

I am currently trying to recreate a PVsyst run I performed two month ago. I would like to hit the E_grid output as exact as possible but even if I use the same loss and design assumptions as the previews run (PVsyst report is still available), I am not getting closer than 17MWh to the previews production (138627MWh total). When I compare the two reports to each other, the only difference is within the Array Operating Characteristics. Umpp and Impp values are slightly different than the previews run. I am using the Trina TSM-310P14A PVsyst database module for both cases so I am wondering where the differences within the U and I mpp come from?

Are there any PAN updates that happen even if I do not update the PVsyst software?

I am using V6.22 which was also used for the previews PVsyst report. Loss Diagramm shows the exact same values than the other run. Meteo and components are inline.

Do you guys have any idea where this difference comes from?

Thank you

MK

[André Mermoud]

I can't give a definitive explanation if I don't reproduce the problem by myself.

It is not clear what are the conditions between your two runs, if it is with the same version of the calculation version, etc.

Some hidden parameters may have been changed.

In the Parameter's part, the Imp/Vmp values are computed from the model at 50°C. The data of this module have not been changed in the database since 2012.

However the reference temperature may have changed.

There are many calculations by successive approximations in PVsyst. Usually they give stable results, but there may be exceptions.

Now please admit that a discrepancy of 0.012 % is not really worrying...