Modeling losses when Vmp is lower than the MPPT range

[Shwetha Vara]

 

• How does PVsyst account for losses when the temperature-adjusted Vmp of the panels falls outside the microinverter’s MPPT operating range? What is the typical impact on power production accuracy in such cases?

• Which inverter parameters in PVsyst can be adjusted to model the power reduction accurately when this condition occurs, ensuring the losses are properly represented?

 

[Michele Oliosi]

Hi, PVsyst will use the operating range to displace the operating point on the IV curve.
This displacement away from the MPP will cause losses, captured in the variables IL_..., e.g. IL_Vmax for the maximum voltage. The parameters here are the Vmax and Vmin parameters.

Note that a different yet related loss, the derate at very high or low voltage levels (or more generally as a function of voltage), is not captured by PVsyst. We do only model a voltage dependence by means of three caracteristic efficiency curves based on three ordinary voltage points. However this may not capture the full voltage derating curve.