I am putting together a grid-parallel ESS system using a Mutiplus II 5000/70/50 unit plus a 460Ah 48V LiFePO4 battery.
I only have one mains connection to make to the buildings existing consumer unit.
Should I be using the AC IN 1 or AC OUT 1?
I have tried both. When using AC IN 1 the startup is less dramatic, I presume there is inrush current limiting on AC IN 1? Using AC OUT 1 the MCBs are prone to tripping initially, it takes a bit of coaxing to get it to start up.
NEVER CONNECT THE AC OUTPUT OF A MULTI/QUATTRO TO THE AC SOURCE !!!!!!
You risk damage to the unit if you do so, plus there is no safety circuitry to disconnect the unit from the source if there's a condition that would otherwise shut down the Multi/Quattro.
When the Multi/Quattro starts up, it assumes it is isolated from the AC source and will probably attempt to generate power (inverting mode) WITHOUT synchronizing to the AC source. This is most likely what is tripping your breakers, but more importantly risks blowing up the inverter core.
You can connect the Multi/Quattro to just the AC source and it will assist in feeding the loads IF the AC source is accepted by the Multi/Quatro and if it is configured properly with an AC input meter (including I think the Multiplus II external current transformer). But if you loose the grid, the Multi/Quattro will be isolated from the loads. It's better to connect at least the critical loads to the output of the Multi/Quattro so the battery can power those loads.
@DJDemonD You should be using AC IN 1 if you are using only one connection of the Multiplus. If you used AC out, you run the risk of back feeding the grid in the event of a power cut but you will need the 100A CT sensor on your incoming tails from the grid when using AC IN 1 in ESS mode.
A few photos and a schematic of my install in the photos section of my VRM portal.
https://vrm.victronenergy.com/installation/171934/share/db6807bb
Not sure about this <you run the risk of back feeding the grid in the event of a power cut >.
AIUI when you first apply 230V ac on AC-In the Multi checks the voltage and frequency and synchronises the inverter before closing the anti-islanding relays. So if you connect the grid to AC-Out it will not be able to go through this process and the relays will not close so it is not surprising the OP has trouble starting it up.
BTW thanks for the pix, how did you get on with testing the scheduled charge inhibit using Aux 2?
Thank you, Jason. We are running parallel to the grid, we do not have the current sensor, but we are using ET112 energy meters. Now we have it connected to AC 1 IN it works. We're just tuning our batteries.
