Hi!
I am currently planning to do some upgrade to my offgrid cabin. Today we use two 35 kVA three phase diesel generators (one in standby) to supply power to the cabin. The average power consumption is about 50-100 kWh per day, but most is used in the morning and evening. Peak power is just under 10 kW, during most of the day it is only 1-2 kW. I therefore want to install about 20 kWh of Li-Ion batteries to be able to shut off the diesel generators during the daytime.
There are only a couple of three phase loads in the system and none of them need to be able to run while on battery power. I got hold of an older 10 kW 48V Quattro 230 V that I am planning to use for this purpose.
Would it be possible to just connect the Quattro inline to two of the phases in the system and then run single phase when on battery and three phase while on genset ?
My initial thought is that it should in theory be possible as long as the inverter section in the Quattro never runs at the same time as the genset ? Then make sure i rewire the fuse box in the cabin to ensure that all the loads that i want to be able to power from battery is connected to the two phases coming from the Quattro.
I believe that my genset has contactors for the supply, so when the genset is not running, the third phase would be physically disconnected from the generator. I understand that i will also need some contactors with some smarts to ensure to disconnect the two live phases on the three phase loads when on battery to ensure that i do not damage the equipment. Running with 2 phases live on a three phase load is likely to cause problems :)
A bit unusual setup I am sure, but if anyone have some thoughts or have done similar things I would be very interested to hear about it. The simple solution would probably be to purchase two additional Quattros, but that would be very expensive since i do not really need three phase.
At the same time I would like to not change over to a pure single phase system as my gensets are three phase and it would be good to get some of the loads that i do not need to be able to power off battery to be on other phases on the genset so that I get a more even phase load on the genset while it is running