Inverter output power by .OND file

[Andrés Fernández]

Hi everyone,

I’ve run into something odd in PVsyst and I’m hoping someone can help clarify what’s going on under the hood.

The situation:
I’m using an inverter “.OND” file supplied by the manufacturer. In both the Main Parameters and Output Parameters tabs, the inverter’s Maximum AC Power is listed as 1265 kW (at low temperature, so no derating). However, when I look at the DC-to-AC performance curves (DC input power vs. AC output power), the data only go up to 1100 kW—which is the nominal power rating.

My questions are:

1. Which number does PVsyst actually use when simulating maximum AC output? Does it honor the 1265 kW value from the parameter tabs, or is it capped at 1100 kW based on the performance curve data?

2. If PVsyst does cap the AC output at 1100 kW, is there a way to override this (e.g. by editing the curve or adjusting settings) so the full 1265 kW is available under ideal conditions?

I appreciate any insights or experience you can share—thanks in advance!

[Muhammed Sarikaya]

Dear Andrés,

Can you please send us your .ond file at support@pvsyst.com so we can examine it? Also, could you explain your issue in your email?

Regards,

[André Mermoud]

When you have a nominal power, defined up to a given temperature, say 50°C, and an enhancced maximum power up to lower specified temperature, say 20°C, the simulation will use the curve shown in the inverter's definition dialog, page "Output parameters": 

The inverter temperature to be used during the simulation is defined in the "Energy management" dialog:

Now the efficiency curve is specified by points at different powers, and  interpolated between these points at each time step. If the actual power is over these points, the efficiency curve is simply extended linearly.