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Tobias Franklin avatar image
Tobias Franklin asked

ET112 ESS Distribution Board Installation

I am confused as to how to install my ET112 meter. I have a zigbee to send the meter info back to the Cerbo GX located in the garage.

(my setup is a DC coupled PV ESS install on a house in the UK)

Question 1: how do I wire in the meter? I need a simple-to-follow picture/diagram, my presumption is that is goes to the left of the main breaker switch and the live goes in position 1and out of position 2 with power from the Neural at the bottom?

Question 2: should I be running AC in to the inverter? At the moment I don't think I have setup the system to charge the batteries via any other means than via the MPPT. So should I run an AC in and also an AC out on the same cable that feeds the garage circuit?

Question3: I have 2 sockets running off AC out 2 - I wanted to have these as 'always on' even if there was a power cut but I can't see where you enable this output (the system isn't get wired into the house circuit which I was going to use AC out 1 for).


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Multiplus-IIESSEnergy Meter
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photo-2022-11-24-22-21-10.jpg (141.9 KiB)
photo-2022-11-24-22-19-42.jpg (89.2 KiB)
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Jason - UK avatar image
Jason - UK answered ·

@Tobias Franklin

1. You need a means of isolation to the ET112 sub-meter so after the main isolator should be good. Also inside the consumer unit is best as installing the ET112 surface mounted is not advised as part of the L+N tails going into and out of the ET112 can leave a bit of the expose copper on show.

2. You mention you have a ESS system but the photos look like a stand alone / off grid set up with no obvious connection you your house AC distribution. Feel free to have a look at the photos on my VRM portal which show my set up and also my AC schematic.

https://vrm.victronenergy.com/installation/171934/share/db6807bb

3. AC out 2 disconnects in the event of a power cut to a ESS system. You would be better off taking the sockets from your main house distribution, and having the Multiplus connected to your house distribution that way both the house and your garage socketed use the power form your ESS system.


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Tobias Franklin avatar image Tobias Franklin commented ·

@Jason - UK at the moment the multiplus out isn't wired into the AC - I was going to connect it into the main cable that feeds the garage (same circuit as the house) I was told that works fine to feed the house with power.

So I was 'sold' this as configurable for ESS so that I could push power from the multiplus into the main house circuit - but am I right in thinking this is going to hammer the battery because the solar has to first go via the MPPT into the battery before it can be used by the multiplus into the house?


Or do I HAVE to buy a PV inverter to get this system working correctly? Or is that just an item I can add-on later?


I'm slightly concerned because this is all really expensive kit and not sure I have it right?!

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Jason - UK avatar image Jason - UK Tobias Franklin commented ·
@Tobias Franklin If your solar array is generating 500w and the house is using 500w, then your battery state would not really change but obiously if you are pulling 1000w but only generating, then your batteries would supplement your solar generation. To note there are losses when going from AC to DC and vice versa so if you are pulling 500w, you need 600w of generation to cover the losses.

Yes, you do appear to have a ESS system, just not connected to the grid on AC in at it would need to be for a ESS system.

PS - regarding the comment of keeping the garage socket on AC out 2, Ive just ready you can set up an assistant you keep AC out 2 live in the event of a failure of the supply into AC in therefore you would be able to connect the mains to AC in 1 and keep your double socket connected to AC out 2 but it would be better to have your sockets on AC out 1 if you are not using it for anything else.

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Tobias Franklin avatar image Tobias Franklin Jason - UK commented ·
Thanks @Jason - UK I had a mild panic then haha - I think this setup will do me for now, so long as it works basically.


I will take your advice on the sockets, so its an assistant to keep ac out 2 open, I just thought it would be handy to have 2 live sockets in the case of a grid down as I know the main house will have to be isolated automatically.

So basically I just need to follow your advice re installing the meter and link the multiplus to the AC (out only, I don't think I need to use in).

And then I should be done (barr any assistant setup etc)

Is that correct based on what you have seen?

(Quick background, I am a programmer so figured I could work this solar stuff out and save myself 6k by doing it myself. I think I am almost there but had to do a lot of learning and climbing around on roofs to get to where I am now!)

Thank you very much for your concise help!

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Jason - UK avatar image Jason - UK Tobias Franklin commented ·

@Tobias Franklin Do not connect your house distribution with grid connection to AC Out1. This is very dangerous! In the event of a power cut, the Multiplus will not be able to disconnect from the grid therefore you would keep the grid live. The grid side must go on AC in. The AC outs can only be used for AC loads.

Note that officially you must submit a DNO application for your installation. G98/G99/G100 depending on the system type and the size of the potential generation and export.

ESS will not work anyway if you connect your house with grid connection to AC out1 as it needs a live supply on AC in. If the network find out you have connected generating equipment to the grid without permission you'll be in a expensive situation as the fines are big.

With the greatest respect, I think you need to do a bit more research before you progress any further. I did not fully understand you wanted to connect your house with the grid to AC out1.

Edit - The network will know you have connected to the grid with your system as you will start exporting albeit a very small amount to the grid due to the latency of the ET112 meter and all modern meters having both import and export metering built into them. When that information is received by your supplier, they will automatically flag it up as I illegal generating installation.

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Tobias Franklin avatar image Tobias Franklin Jason - UK commented ·

@Jason - UK I will look into this again, but I was informed by midsummer and also another totally separate company that given the size of my equipment being below 3500VA output and not more than 16a output (and so long as the system was setup as ESS and to always pull eg 20W from the grid) then no MCS Certification is required.

I just have to submit my details to the DNO as you listed.

I will double check but I am pretty confident that this is the case.

I will make a few calls around before hooking anything up, I 100% don't want to get any of it wrong!

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