@AliG ah without an export meter it'd be very tricky to do any useful measurement unless you can remove all the other load (e.g. trip all breakers briefly).   Btw 3x inverters could be ab expensive way to do this, one 3-phase inverter is less than the price of 2 single phase inverters, in the quotes we got   The A1140 is the one I pasted a link to install manual for upthread. Useful to know that they're used by some suppliers, can I ask which co. installed it for you?  a