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Hi, currently running an MPii with 4x Pylontech US2000s. Everything is great. I don't use the AC out, it's running as a grid tie ESS. Using solar too on the AC side.
What I want to do is add a second Multiplus with a different type of battery (thinking EVE LiFePo4 cells and Batrium BMS).
If this works then I can scale the system up over time with more MPs.
Is this feasible? or do both the multiplusses need to be connected to the same battery?
If they are being programmed as parallel then they share a battery bank.
There is some more documents and information linked in the related resources box on this page - to the right on laptop - to the bottom on mobile.
How does the existing MultiPlus know when it is OK to recharge the battery bank? Time of day? Do you have TOU electric rates?
I manually schedule charge time, also the battery charges from surplus solar.
So can you confirm that the proposed system is OK? Would they operate effectively as a master unit and 'see' two batteries?
It is a requirement for Victron - it is in the manual.
if there is a voktage difference - if there is an amp difference - they will perform differently and not load share.
There is if they they do not share the load equally one bank will deplete faster than the other - one unit will then shut down before the other and then you will see errors on the GX - for example error 3
@mvas yes I'm on a TOU electric tariff but also I have a lot of solar panels.
This is why I'm asking the questions - I'm trying to find out if it is possible to make the two (or more) units act as one or whether they need to be run and controlled as separate systems. Bear in mind I would potentially like to go beyond two units.
Can I assume at least that they will happily sit on same AC supply together?
I guess we are using terminology differently here.
@Alexandra So I'm using the inverters to enable me to use batteries. My setup is an ESS setup, so I'm permanently grid connected. My electricity rates change every half hour and I also have lots of solar panels. So I want to 'bank' electricity during the cheap periods and also store the solar. The multiplus units backfeed the AC IN when discharging the batteries.
EDIT: My install: https://vrm.victronenergy.com/installation/327623/share/3ff0dd7c
"The VE.Bus cluster maintains a single 'global' status for SoC, DC voltage, and DC current. Every DC connection (on every Multi/Quattro and on every battery) has to be connected together to a single DC bus. Do not build systems with separated batteries on multiple (separated) DC bus structures connected to subsets of the Multi/Quattro units in the cluster. This will not work."
A short answer- completely independent of each other in operation and not connected to one GX - they don't need to share a bank.
If they are going to share a GX, be in software told they work together then they should share a bank. (Sharing/connected by VE BUS)
Type is not really the issue, it is SOC and different voltages for charging and discharge levels.
Then the issue of different BMS controls.
You could set up the new bank with same voltages as the Pylontec, then bus bar them, have a BMV for SOC. No BMS comms. One GX two inverters (are they on the same phase or parallel -sharing- on one phase?)
I'd rather not be limited to one type of battery.
I see - so use multiple BMVs to get the SOC info.
Am I correct that if I used multiple systems (multiple cerbos) that they won't talk to each other so they would be in essence separate installations? That's obviously an option but it seems somewhat 'wasteful'.
Yes separate Cerbos means two separate systems, better if your batteries have different charged voltages.
Not as wasteful as overcharging a pylontec or undercharging a different battery.
Connecting with bus bars equal length cabling etc. and with the addition of a bmv etc you might find your costs are about the same a two separate systems.
it does seem like you have a 700 ish watt load on the output of your inverter, didn't find any evidence of grid feedback. I assume your AC PV is on the Input/Grid side of the inverter?
