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tonywbond avatar image
tonywbond asked

Do I need an energy meter ?

I am in the process of researching how to setup my ESS, but whether I need a grid meter or not has left me confused.

The Victron Multiplus II will be sited in my garage which is some way from the grid input into my house. I have 3 separate solar installs on different roofs.

So what I'd like to know is can the Multiplus II still do dynamic balancing between charging and contributing even if there is no grid meter.

If not then does it know when to charge/discharge the batteries, is this manual or can it be instructed to do this by something like an api that I can call ?

Apologies if the question is very basic, I have read lots of documentation, but remain confused.

Thanks

Tony

Multiplus-IIESS
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5 Answers
gazza avatar image
gazza answered ·

This is With grid meter... I have this system with DC coupled PV (No grid-tied inverter on essential).

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sharpener answered ·

Look up the ESS manual, it shows several several topologies. The simplest, also shown here https://www.victronenergy.com/live/ac_coupling:start does not need more than the internal current sensor within the MultiPlus but you need to comply with the 1:1 rule.

Operation is fully automated with the ESS Assistant software.

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gazza avatar image
gazza answered ·

This question comes up a lot, you are not alone. The main issue is whether you are intending to put your loads onto the AC "out" of the Multiplus, if you are then you can get away without the grid meter. However, you will most likely need expensive re-wiring since in your case the consumer unit (ie grid input), is some way from your multi in the garage? You will see from the diagrams that for this format the grid input needs to be the AC In feed.
The whole concept of the ESS system is that you can put the Multiplus anywhere (fed via a suitable MCB/cable from your consumer unit) but then you do need the information from the grid meter fed back to the Multiplus to make ESS work. Take a close look at the ESS system diagram, the Multiplus AC "In" junction is also the feed to the AC loads, AC In of the Multiplus is bi-directional. This makes it very easy to add to an existing house wiring system. I have an identical system to you (with less PV arrays). The only real issue is which method you use to connect the grid meter to the Multi, ie wired or wireless

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tonywbond avatar image tonywbond commented ·

Gazza, thanks for the fast and helpful response.

With regards the ESS system diagram you mention, is there a specific diagram you are referring to ?

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gazza avatar image gazza tonywbond commented ·
...see answer below!
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sharpener avatar image
sharpener answered ·

If you have a long cable run to the garage then 5-core SWA might be a good choice for this, it would conveniently provide both go and return for the AC In and Out. Then you would not need a long cable to a grid meter which as noted in other threads can be troublesome.

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gazza avatar image
gazza answered ·

This is with No grid meter.

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