Inverter 3 voltage efficiencies query

[Grae]

Hi,

We have been looking into the .ond files and utilising the efficiency curves for different voltages. We are currently not using the functionality of efficiency for 3 voltages as we seem to have an issue in generating the curves. It appears when you set the voltage to a certain threshold, you have to set all three voltages manually as they are not generated from the first point entered. Is this an issue, is PVsyst able to interpolate the remaining two efficiency curves, from the original defined efficiency curve (i.e. set the max efficiency curve at a low / mid / high voltage and the other two curves are generated based on this)?

When defining all three voltages with the same Max Euro efficiencies, we obtain the same loss as not using these curves (i.e. having this option ticked or unticked). Sometimes we have seen the profile curves setting a very different profile curve to the curves observed on the datasheets. However not all datasheets have these curves which makes this checking and definition impossible.

Many thanks,

Grae

[André Mermoud]

I don't understand well what you mean when you ask PVsyst for generating the 2 other curves from the first one.

The efficiency profile definitions should be defined by the user, independently for each voltage. These curves are a property of the inverter, there is no "physical" relation between them.

If you define 3 identical curves for 3 different voltages you will get the same results as for one only curve of course. This means that your efficiency is not depending on the input voltage.