question

hubert avatar image
hubert asked

AC decoupled MultiPlus/Quattro in one system, charger only

Hello again Victron Community :),

I'm considering a scenario (I named it ac decoupled system) where in one system there are:

  • 3 MutliPlus units for 3 phase operation, grid connected, feeding power to loads
  • 1 MultiPlus acting as a charger only, no grid connection

Not getting into details why the hell I would build something like this, please help me with my questions:

  1. Can all of that be connected to the one VE.Bus and GX controller?
  2. If so how it will look, will that work as ESS?
  3. Another if, would it be possible to manage Charger only MultiPlus as a generator? Eg giving some relay on/off for starting and showing it as a generator source in a ESS?

In this thread there is similar question, answer is negative (that fourth MultiPlus won't be recognised by GX system), but I was hoping that something maybe changed.


Regards

Hubert

MultiPlus Quattro Inverter Charger
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1 Answer
Alexandra avatar image
Alexandra answered ·

@hubert

No. It has not changed. There is some limited monitoring for the fourth unit, but no ESS control. In anycase you shouldn't be using ESS as you are "offgrid", and it is really designed for grid application. See the section labelled when not to use ESS.

The fourth one can be programmed as a generator with a start stop from the GX for the three phase as it is basically what you are using it for. And no need to AC connect it to L1 just use it as a DC charger.

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hubert avatar image hubert commented ·
Hi @Alexandra , many thanks for posting your answer.

To make my idea more clear: there is no AC connection between 3phase multi and 1 (4th) multi, only DC is shared (same battery).

Let's say 4th Multi is powered by actual generator, so I can take signal from GX and start generator which will power 4th Multi (but no 3phase Multi, nor any phase of 3 phase system). Will that be visible as 'generator input' by GX (and ESS)?

And I'm aware that, ESS is not designed for off-grid systems, this is as a backup only, when grid fails.

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Alexandra avatar image Alexandra ♦ hubert commented ·
@hubert

Ah. Sorry I missed that the three phase was on grid.

There is a trick with has dc system that some people use to track another multiplus with the one GX. But it cannot be connected as a VE bus as far as i know, some connect it with an mk3 to a usb for device list monitoring but that does not appear on the vrm dashboard as far as I am aware. And there is no control through the ess programming.

And no, it will not be seen as a generator as it needs to be AC coupled to the three phase to see its input. And with the multiplus you would have to manually switch in the GX the source to label it as generator unless you are good with programming.

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