Operate MultiPlus II only via AC2?

DIY
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1

Hello,

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I’d like to expand my solar system and switch to Victron. The panels are currently still connected via an AC inverter. An RS450 is also planned to charge the batteries. The setup should be able to charge and discharge the connected PylonTech battery according to the energy meter. A Cerbo is also planned.

I’m wondering whether I’ll be able to charge and discharge my battery with option1 below, or whether option2 is essential (or perhaps a different wiring configuration)?

Many thanks

2

What pv inverter do you plan on having or do you have?

Is the AC PV inverter following the 1:1 rule for AC coupling with Victron?

Does it have any form of communication with the victron system can it be controlled by the system?

3

Answering most of mine own questions:

  1. Attaching “only” via AC-out-2 is a bad idea, becasue to mine understanding it can not back-feed excess into the grid

  2. Attaching purely voa AC-In seems working wine. it can import and as well export power. excatly what I need

  3. I am running the cerbo/multiplus in external-control-mode via modbus. When doing so, it requires with short frequency a keepalive. a single sent command fires, but roughly after 5seconds the victron goes back to zero/halt. I decided to send the last command/actual command in a 1sec interval.

  4. overall my own setup at home is very much mre complex then in this. thread shown. I am running in parallel a Multi-lus, goodwe and solis battery invterers. all attahced to a bunch of AC-coupled SMA PV inverters. So a wild mix of ddifferent vendors. most critical is, that the both 3 battery-inverters need a control-algo to ensure that while one inverter is charging, the other inverters do not discharge to compensate this. The goodwe in mine system is the free-runner. Has its grid-meter and does its best job to keep grid at zero.
    The solis measures the goodwe ampere via a shunt and reads the grid-total voi a SMA energy-meter. Having a RPI sitting inbetween the JK-BMS and the solis canbus, the RPI controls the solis via POPylontech-canbus protocol by reading GRID and GOODWE state. to adjust slowly its charge-discharge. Works like a charm.
    Now beacasue I think victron is just the best, but not throwing away existing gear, I added a Multiplus II 6k5. Now control-loop a little bit more complicated, becasue the victron need to monitor both the other inverters and then via external-control decide if charging or discharging is a good idea..
    All a bit messy, as I finalyl more then tripled the work I need todo for monitoring. 3 independent battery-invterers and then the interlock inbetween them…
    But in general, initial testing shows its doing fine. Now careful monitoring and fine-tuning.

By the way. I upgraded to v559 Version for the firmware. did a lot of chnages yesterday and unlear finally which chnage made it working. But the 559 seems solis for now.

thanks