question

alexcpu avatar image
alexcpu asked

MultiPlus-II ESS with No AC-Out

I'm trying to work out how to add a MultiPlus-II 5000 for ESS to my existing solar installation.

I think my setup will look like the below image.

Currently I've got the Solar edge inverter and ET112 meter in place.


So I've got two questions that I can't work out (I've checked all the diagrams!):

  1. Can the MultiPlus-II provide power to my house back out through the AC-In, without having to get perform a significant re-wire of the house?
  2. Do I need a CT on the Live from the Solar Edge inverter? I'm aware the CCGX can read the data from the ModbusTCP out of the inverter. But don't know if that's sufficient.
Multiplus-IIESS
victronsetup.png (193.3 KiB)
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2. No, you can connect the MP with the SE WR over Modbus TCP

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3 Answers
sean avatar image
sean answered ·

1, yes - so it just needs to be connected to your consumer unit via a suitable breaker.

2, Prior to installation of the EM112 I extended the CT approx 30m and simply plugged it into the 3.5mm socket on the MP, which bypasses the internal CT. The external CT goes on the main incoming grid feed. I have a Fronius Primo, and a Fronius smart meter, the generation is seen on the Venus device.

So in terms of your schematic CT? is not required.

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Rob Duthie avatar image
Rob Duthie answered ·

1: Not really but you can export power by changing the grid set point you can export power and import power. that is not how the ESS system works, you need to have the loads on the AC outs

for the ESS system to work correctly.

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1, That's exactly how my ESS is setup - AC-in is bi directional

The CT or smart meter is used to ensure net zero import, using inverted battery power.

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You don't have to have loads on the AC-out if you have an energy meter installed (or external current sensor).
If you want to have power when the grid fails, you have to route (part of) your house wiring from the AC-out.

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matejs avatar image
matejs answered ·

I have the same situation. I do not want to rewire everything and I want the MultiPlus-II ESS to provide power to my house back out through the AC-In. Sure, I do have critical loads on AC1.

So putting external CT and plug it to 3.5mm2 on AC wire that comes in to my house and limit export (setpoint to 50W) would work?

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This works flawlessly.

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