# question

## Wiring 3 Multiplus 2 in paralel

I have 3 Multiplus 2 in parallel and want to use them in a one-phase grid-system (230V IT) with ESS. Wiring the MPPT and the battery seems easy with a busbar etc. But what about the AC in and out?

I am not allowed to put more than 16A back to the grid.

The load on AC out 1 will not exceed 230V/25A.

The load on AC out 2 will not exceed 230V/25A.

No wires/cable need to be longer than 100 cm.

Question 1: How big should the fuse between the Multipluses and the grid be? 50A?

Question 2:

A: For ballancing the current, do I have to wire each Multiplus directly to the fuse both against the grid and against the load fuse on AC out 1 and 2?

B: Or is it possible to wire the Master Multiplus against the fuses and wiring just between the other two Multipluses?

Question 3: If 2A is correct, I assume that all wires have to be equal and that the size of 2,5mm2 should be nice? Or is it even enough with 1,5mm2?

If 2B is possible, will the wiring be the same?

Anyone that can help me?

1 comment

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Forgot to say that it is Multiplus II 48/5000/70-50

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I think for clarity it would be best that you draw a diagram up of what you are conecting and how you think it should be conected and then we maybe able to help as we would understand what you are doing better.

Also you really should get the company that sold you the inverters to assist you in this instalation

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Why 3 MP? Because I later on will try to convert the 230V IT system in my house to 400V TN—S and use them in a 3-phase installation. Then I can double my delivery back to the grid (from 3500W to 7000W).

I have red the manual but are still not certain about the wiring. I assume that in my question nr. 2, A is the right answer. It means in fact 27 cables:

AC in: 3 x 3 going from grid-fuse to each MP and earth.

AC out 1: 3 x 3going from each MP to the load fuse and earth.

AC out 2: 3 x 3going from each MP to the load fuse and earth.

I have tried to visualize in the following diagram.

3 MP 2 parallel 1-phase.pdf

Why the question about fuse size from the grid? Because of the limit of delivering 16A back to the grid on one phase.

Maybe I have misunderstood the manual, but I think it says that in that limited case,the MP will take no more than 16A from the grid either. So a 25A fuse should work. And divided in 3, that should be not more than 8,33A to each MP, so cable dimensjon could be rather small.

Am I right?

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jeibre ·

Why not dimension the cables so they can handle the feature conversion to 400V?

so for 25A use 4mm^2 cable, and make very sure they are the same length, and not too short. output cables: the same if you're using 25A breakers.

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Why do you want to use 3x 5k unit? why not a single 15k unit? much easier to install (except for mounting it...it's heavy!), much easier to configure, monitor, etc.

Some extra information about multiple units working together:
https://www.victronenergy.com/live/ve.bus:manual_parallel_and_three_phase_systems#configuration

And as an extra advice: get someone (like a Victron installer) to help you with configuring / installing the system, so you don't make any expensive mistakes.

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Sorry, my comment was ment for you, but did go to Paul B. But happy if both of you comment :-))

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