Multiplus II GX with ESS External control and UPS

DIY
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1

Hi,

I have managed a while back to get the multiplus II GX working with ESS and external control using modbus.

But I am a bit confused about the UPS at this stage.
As I understand AC-OUT1 will be an inunteruptable power source, even when AC-IN drops.
But I cannot bridge my AC-OUT1 to my AC-IN.
As I did this initially thinking it would work this way, but got some weird side effects with double output and got told to remove it immediately, then stuff worked as expected.
Ref : Critical loads causing excess export when setting modbus register 37

What I think I would need is that AC-OUT1 only becomes active when AC-IN drops and vice versa?

Any info on the UPS and how to configure it in my scenario is greatly appreciated.

Thanks!

2

Why?

3

You don’t need to as the inverter does this itself.

UPS is set in the internal programming.

4

Okay, maybe the simplest of questions first, if my grid drops will AC-IN be used as a UPS and supply power to my house ?

5

No only ac out 1 will do that, the loads you want to be powered when grid fails need to be connected there

There is no battery backup power if your multiplus is in parallel connectd to your house (house on ac in side)

6

Hey Marc,

I want my entire home to stay powered when the grid fails, and I want it without power interruption (UPS) so that would mean AC-IN and AC-OUT1 should be connected afterall ? Or how would you wire this ? At this time I have a manual switch on AC-OUT1 which I would have to flip over when grid power is lost, but I would want it as UPS without the switch.

7

Can you make a drawing of how everything is wired?

If you want your entire home powered with automatic battery backup (ups) then your entire house has to be on ac out 1 without a switch in between

And is your multiplus and battery bank big enough to do that? Do you have solar? Ac or dc solar? Where is it connected (drawing)?

Ac out can never be connected back to ac in, thats not how the system works…

8

Sure, here you go.
So in this current setup if the power fails, I would manually flip the first breaker off and the second on.

image
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9

You cant do that, thats dangerous if grid is connected there also!!

You wil also power the grid that way if its connected directly to it

Please read the manuals and system designs that are available online

If you want your whole house powered (if system and battery is big enough) it should be wired like this:

Grid > utility meter > (grid meter for multiplus optional) > fuse/mcb/rcd > ac in multiplus

Ac out 1 multiplus > fuse/mcb/rcd > house distribution panel

That way it will do what you want, when setup right with automatic battery backup

For fuse/rcd/mcb follow your local electricty rules!

10

I forgot to mention I would also flip the grid breaker manually first.

But this would mean that AC-IN and AC-OUT-1 are connected.
Since house distribution panel is also connected to the grid.

How I read your comment :
Grid > utility meter > fuse/mcb/rcd > AC-IN
AC OUT 1> fuse/mcb/rcd > house distribution panel

11

You will need to split up your house panel:

Grid part to multiplus ac in only

and you have to disconnect house panel from grid and connect it only to ac out 1

12

Similar to this:

IMG_6857
IMG_68571179×816 153 KB

So nowhere a connection between ac in and out of the multiplus

1 Like
13

Ok perfect Marc, I understand now.

Thanks again for your time and teaching me! :slight_smile: :beating_heart:

14

Hey @DuivertNL do you have a company from which you install victron systems? If so could you share the details?

15

I dont have a company

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