I am running a 3 x single phase system each with own solar bank (5kw), MPPT controller (250/100), Multiplus 48/5000 and Venus GX unit. The system has a single 48V battery bank and BMV unit.
My plan is to be able to run the house off solar during the day and certain appliances at night off the battery until the battery reaches a certain SOC, then switch over the grid supply. I do have a reasonably stable grid supply so the idea is to reduce electricity costs as well as provide a backup for essential appliances during a power failure.
I would like inverter 1 to run down to 75% before switching over and the other 2 to switch over at 95% - any ideas how I can achieve this? The problem I have is that the built in SOC readings from the inverters is unreliable with a single battery bank as they have no idea what the other inverters are doing.
Ideas would be appreciated.