Reference nominal power

[laurahin]

Hi,

A second definition of the reference nominal power was recently added to PVsyst.  The user can now choose between PNomPV(ac), which has been the default, and PNom(Inv).  My understanding is that the reference nominal power should represent the maximum power expected to flow through the AC system, and that PNomPV is based on the array size (nominal DC power) times the inverter efficiency while PNom(Inv) is the total inverter rating.  Since in most cases, PNomPV is higher than the total inverter rating, it makes sense to me that PNomPV should be selected.  My question is this:  How much difference do you expect this choice to make?  I believe that, at a minimum, it should affect the MV transformer loss if it's defined using the "Generic values" rather than the datasheet values, but I have tried running an example and found no difference in the result.

Thanks,

Laura