Dear Andrew, Hammon, PVsyst users, I'm also trying to understand the calculation behind the "AC Ohmic losses" in the "detailed losses" section. I tried several calculation but can't calculate the same values as calculated by in the section "AC circuit: Inverter to injection point". Further I have the following questions that adds on: - From where do the electrical values (Pac and I) behind the "STC:" writing come? These values aren't the same as the given values of the inverter? Please check the values of the inverter and values given in the section "AC circuit: Inverter to injection point". - If we have one tri-phase inverter and we connect it to the grid with a 3x10 mm² (fase) + 10 mm² neutral cable, we have to choose 30mm² (=3x10mm²) as cross section or 10 mm²? If right what Hammon says, the answer on this question should be 30mm². => If the length of cables (3x10mm²) is 10 meter, than the length to be filled in should be 10 meter, OK? Now if we have two inverters that are connected the same, should we fill in as cross section 60 mm² and the lengst stays 10 meter? Thanks for your help and reply!