3phase backup design.
Good day everyone. I would like to have some advice on an installation I need to design.
My client has a 3phase supply at the moment and would like to back-up the whole system, meaning the solar system must be able to carry the whole installation which is currently a 50amp 3phase supply. The db is inside the offices and I would need to have a custom made box installed outside to house inverter and batteries. What would be my best and most cost effective solution to enable this type of back-up from using sunsynk equipment. Any suggestions or advice please 🙏.
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Hi, I’m not expert but can tell you some of the things I’ve discovered. I have a 12kW 3 Phase hybrid inverter. so in theory can supply the 50 amps you need, however it’ll only do 6kW on a single phase or 4kW on each phase, if you’ve got all three phases drawing the max. So make sure you split your loads up across the three phases as best you can. As for the batteries, if you run 4 (5.12kWh) batteries the inverter is able to charge/discharge at 200A in parallel (50A @51.2v each), however as the connectors are only rated to 120A, at full power you’ll max out at about 6kW. You could explore running the batteries in series, but I’ve not done this, it would take more cable and connectors and I’m not sure it’s supported. If you have solar as well, during the day I’ve got close to the inverters max output using both batteries and solar, with a three phase car charger, but in most normal usage I don’t come close. I’ve also got non-essential things like the EV charger arranged so that it’s on the grid tied side, so goes off if the grid goes down to prevent battery drain or overload. Happy to share more details of my install if that’s helpful.