Difference in clipping loss

[Intertechne]

Dear Andre,

I am wondering why the clipping loss due the inverter overload is different when i compare two identical simulations regarding DC:AC ratio and others simulations parameters.

The only difference is reduced numbers of inverters or a higher number of modules in order to obtain the same DC:AC ratio for both simulations.

There is any difference if i increase the number of modules (higher DC power) or reduce the number of inverters (lower AC power) in the clipping loss output?

The Vmpp value is the same for both simulation because the number os modules in series does not chance. The only change is the number of strings or the number of inverters.

There is an explanation for this?

Thank you in advance.

[André Mermoud]

The clipping loss is not only dependent on the DC:AC ratio, but also on the strings distribution on different MPPT inputs.

As an example if you are using inverters with several MPPT inputs:

- when you use the option "Uses multi-MPPT", each MPPT input will be considered as an independent inverter with half-Pnom

In this case, as an example, the MPPT with 2 strings may have overload when the MPPT with one string will not.

- when you uncheck this option, the inverter will have 3 strings on 2 MPPT inputs, but the power may be shared so that you have no (or much less) overload. This is the real behavior of most inverters.

This is explained in detail in the help "Project design > Grid-connected system definition > Multi-MPPT inverters: power sharing"