I am installing a Victron Multiplus II in combination with a GoodWe 8000w Solar inverter.
The connections are Grid to multipluss II AC out to loads and the GoodWe is connected to the AC out. I have also connected 3 US5000 pylontech batteries, these are connected to the cerbo GX with the correct cable. The Multiplus II is connected via the VE Direct bus.
Also use an Android tablet reconfigured to just run the remote console.
So far so good.
But when I try and add the ESS assistant in the VE Config the Multiplus seems to fall over and refuses to work properly, it tries several times to connect to the grid and after about a minute it shuts down, with only the red light for the inverter on. Re-configuring everything back to how it was before works but the Multiplus takes about 5 to 10 minutes to sort itself out.
If the PV inverter supports AR-N 4105 , then it should work without any problems.
As described in the design guide, for the MP2 10K you need at least 7x US2000 = 4x US5000 = 400AH without AC coupled PV.
Per 1.5 kWp installed AC PV power requires at least of 4.8 kWh of battery storage = 8KW / 1.5 = 533AH = 600AH = 6x US5000
You can measure the PV power using a Victron Energy Meter configured as a PV inverter or, for example, using a Shelly as a virtual PV inverter in Node Red of the Cerbo GX.
For precise help, please provide an exact wiring diagram.
Dynamic cut-off could be set to 46V for all values as test, maybe even less with Pylontech as they have 15 cells and not 16 cells like other batteries resulting in lower voltage.
Depending on the grid code, the MP2 8k might be allowed only in 3-phase configuration. Many grid codes disallow more than 4,6kVA phase imbalance., like Germany.
Which grid code is configured and what is your local allowance for phase imbalance? Or du you have a single phase grid connection like in UK?
I think the problem could be a GoodWe inverter on the AC out. Check that AC grid setting (Country Standard) on the GoodWe is Micro Grid, Island mode or something similar if it has that kind of setup. If it doesn’t have, than you can not use that inverter on the AC out. You can only connect it to AC in. I once had SMA inverter on the AC out and the country standard was not set to Island Mode. Multi was functioning erratically, there were wild fluctuations of the voltage and it could not charge the battery. After I have set it to Island Mode, everything was working well. Be aware that even if your inverter would work in that setup, you will not be able to control how much power it will feed to the grid. That is only possible with Fronius. And from my experience, that is the best combination, and it works like a charm.
It has been solved. Initially tried a Shelly EM module as I had a spare one, but for some reason it couldn’t get a strong wifi signal. so ordered an ET112 power meter and a USB to RS485 adapter. Set up was really straight forward and took about 10 to 15 minutes to do. Then asked Chat GPT about setting up ESS on a Multiplus with Pylontech US5000 batteries. This pointed me very much in the right direction. And its now working as planned.
