Question about AC input/output of multiplus 2 inverter

DIY
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1

Hi,

I have a 12.8kWp solar system (2 arrays 6.4kWp each), each array goes to an MPPT 250/85, which in turn connects to a Lynx distributor, a 16kW battery, and the MultiPlus-II 48V 8000VA 110A 100A inverter.

This in turn will be connected to the house electrical system.

My question is about how the AC is connected through the inverter, I have drawn a simple schematic of how I think the system should be (I stole this from possibly a member here and modified it, so my apologies for that if you see it, but it suited my needs), my concern (if it is a concern), is that the incoming from the grid is connected to the AC in of the inverter, the AC out 1 then feeds the house consumer unit, in other words, all the power the house uses will go through the inverter (including using solar and battery stored power) then onto the consumer unit.

We are using on average from the grid (the solar or battery isnt connected yet) at the moment about 11kW per day (may increase a little as we head towards the winter months)

Is this the correct way to connect the inverter in this case, is the inverter able to take all the power we use through it.

The two AC isolator switches are for the following reasons, the inverter is in a different room to the main fuse, meter and consumer unit, so I have installed a two pole isolator switch to completely disconnect the grid from the house if needed in the meter room, and in the inverter room I have installed a 4 pole AC isolator switch that completely disconnects the AC in and AC out1 if maintenance is needed (rather than having two individual AC isolators for AC in and AC out1)

This way the grid can be totally disconnected by the isolator in the meter room, but the house will still run on solar and batteries, and I have two forms of isolation from the grid, one in each room, which I think is a requirement if the inverter is on a different room to the meter and main fuse.

Thanks for comments and advice in advance.

Grid connection simplified
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2

Any advice on this please ?

3

No reply so continued with the wiring, although not connected to the grid yet, but cables are in ready, (the blue and brown cables are the power in from the grid, the two grey wires are power out to the consumer units (ran out of cable so they are just temporary), both go into AC isolator and as mentioned isolated at the moment, all 4 AC cables are 25mm

All the battery cables (including to the inverter) are 50mm, I think this is adequate, although I have seen that its possible to double up the cables to the inverter, or possibly use a 70mm cable ?

All the cables will be tidied and some trunking when I know the system is correct.

Any comments on the Earthing arrangement, the main earth coming into the inverter with the brown and blue cables and connected to the inverter busbar, then individual earth cables from the busbar to the other equipment, the two MPPT’s, into the DC isolator which then runs up to two solar combiner box’s, one for each array, and the battery, I didnt earth the lynx distributor as I was a little confused as to how to earth it, all I have seen says to earth to the negative bar, but not sure if thats ok or not as thats all on the DC side, any comments please ?

Please pull the design apart if you see any problems with it, I am learning still.

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4

Hi 1x 50mm2 on 8k inverter is way too low, check the minimum in the manual: 2x 50mm2

Quick look, rest looks ok :blush:

5

You mean MultiPlus-II 48V 8000VA 110V 100A ??

11kWh ??

If your continuous load doesn’t exceed 6kW it should work, otherwise you night get a thermal problem with the Multiplus.

6

Actually I think up to 5 meters 70mm² should be OK for the 48/8000

7

Nope is also too thin, see the manual:

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8

Sorry, can only find data for a 48/5000 110V 70A unit ???

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9

Thanks Mark, yes I will add another couple 50mm cables tomorrow, cheers

10

This is the one I bought Victron Energy MultiPlus-II 48V 8000VA 110A 100A – PMP482805000 | Powerland.co.uk

11

And you have a single phase 100A connection to the grid ??

Crazy :shushing_face:

12

So do you think I need to double up on the cable from the battery to the lynx too ?, would be a bit awkward to do that though ?

13

The incoming single phase cable from the grid has a 100A fuse, I think thats normal in the UK these days

14

OK, strange things going on, a threephase world makes a lot less problems.

15

I think the 110A stands for 110A max battery current, the 100 stands for 100A input current, its 230v

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16

This is the UK, everybody else is wrong :rofl: :rofl: :rofl:

1 Like
17

I’ll come over, pull the plug and the UK is history, goes down like the Titanic…

18

The UK is already history with the shower we have in government running the country, we will soon be back living in caves and cooking food over a fire

19

Yes you need to have 2x50mm2 from battery to multiplus also