How to calculate losses for the array

[Tritec]

Dears,

I'm simulating a PV plant .This plant has 3 inverters, each inverter has 8 string box and each string boxs has 24 string.

I wish calculate ohmic losses for the array with the Detailed computation option, in PVsyst, I need to put average lenght in meters per circuit.

My question is, what I consider as a circuit? All the plant, one inversor or other?

Thanks.

Diego