Dear André, I have the same problem described above by Katinka: how to set PVsyst system for a correct simulation of Huawei 185 KTL string inverter, in case the number of input strings exceed 18 i.e. 2 strings for each of the 9 MPPTs of the inverter? This string inverter is designed with 18 string inputs and have 1 MPPT each 2 inputs (total 9 MPPTs); Inverter multi MPPT feature cannot be disabled (unless you put in parallel all the strings before inverter input). Therefore in PVsyst system I tick the “multi MPPT” option. Everything is fine with the simulation when there are max 18 strings each inverter. However, Huawei allows also connecting 3 strings (instead of 2) to each MPPT, using a Y connector on one of the two inputs of each MPPT. This way you can connect more than 18 strings to each inverter. But, according to inverter data sheet, each MPPT has a maximum input current of 26 A and with actual modules, often the Imp @STC of 3 strings exceed this limit. In this case I am not sure what is the more correct PVsyst system setup: - If I thick the “multi MPPT” option, in simulation results I have severe “over nominal power” losses. - If I don’t tick the “multi MPPT” input instead the “over nominal power” losses are negligible. I tried also defining two arrays, one having 2 strings each MPPT and the other having 3 strings each MPPT; then I used the “power sharing” option. In this case: - If I click the “same DCAC ratio for all arrays” button, in simulation results I have negligible “over nominal power” losses (same as “no multi MPPT”). - If I don’t click that button, in simulation results I have severe “over nominal power” losses (same as “multi MPPT” option). The difference in simulation results in the two cases is really significant: about 3-4% losses using the “multi MPPT”, almost zero losses disabling the option. What is the more correct PVsyst system setup for this string-inverter configuration? I guess it is the “multi MPPT” option, since in inverter data sheet EACH inverter input has a current limitation. However I see the lower performances in PVsyst output are categorized as “over nominal power” and not as “over nominal current” losses, therefore I am not sure if the “multi MPPT” is really the correct option to use. Can you please help me? Thanks in advance
