question

p-rogalski avatar image
p-rogalski asked

ESS and energy meter - what it's function?

Hi guys,

I understand it may be a silly question but what is the function of the energy meter in the ESS system?

I have EM112 coming soon but don't see the reason or its purpose. VRM is collecting the usage, then I have a smart meter etc. so it's all calculated or transparent. Does it work as a load detector?

Appreciate your input.

ESSEasySolar All-in-Onegrid parallel
7 comments
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Rob Duthie avatar image Rob Duthie commented ·
Hi

Yes it is required in controlling the loads power requirements etc?


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matt1309 avatar image matt1309 commented ·
Hi @P. Rogalski


If your system is wired:


1. With no loads on grid/ACIN side

grid -> multiplus -> loads. And there's no PV or loads on grid side of multiplus then no need for the meter in my opinion.


2. With loads on grid/ACIN side:

grid <-> loads <-> multiplus -> critical/offgrid loads.

Then the victron system doesnt know how much power to "back feed" to cover the loads on grid side as it has no communication with the smart meter.

If the victron system does know incoming grid data then it can calculate the amount to output on the grid side to cover those grid side loads.



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p-rogalski avatar image p-rogalski matt1309 commented ·

Thank you for your feedback guys. It does make sense now.


However, does it mean that the ESS only use an energy meter and not a current transformer? Initially, I got a current transformer CTR12xxxx but then I realised it doesn't appear in the "ESS design and installation manual" hence a meter purchase.

As you can see I'm preparing for ESS startup for my off-grid system.

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sharpener avatar image sharpener p-rogalski commented ·
AFAIR you can use a CT on the input side to measure grid current in place of the internal CT, but you need to use a proper meter on the load side if necessary.
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p-rogalski avatar image p-rogalski sharpener commented ·
Great feedback Sharpener. I can see you are very clued up. I'm a bit on the thick side :).

Can you help me with my last concern?

If my load is a consumer unit the energy meter needs to be between the Grid and the consumer unit? My electrician says that the energy meter can be connected in line: Grid - consumer unit - energy meter. Would it work correctly?

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matt1309 avatar image matt1309 p-rogalski commented ·
Hi @P. Rogalski


You can use a ct clamp in place of energy meter on the incoming tails.

The energy meter needs to be before all the loads you want victron to know about/cover.


So in your example doing grid->consumer unit -> energy meter is fine as long as all of the loads/circuits are connected on "behind/after" the energy meter

ie grid-> consumer unit -> energy meter -> RCDs/breakers/mcbs for each circuit in the house.


If electrician opts for this route they'll probably do.

Grid-> Consumer unit -> energy meter -> main switch -> RCD -> mcbs.


(from main switch onwards would be normal consumer unit setup)

They might add another main switch before the energy meter. The physical location of the meter doesnt matter ie inside or outside a consumer unit. It just needs to be before (infront of) the loads. An electrician will know this though so you should be good.




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p-rogalski avatar image p-rogalski matt1309 commented ·
Thank you Matt1309 great feedback and great help. It's all clear.

Have a great day!

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2 Answers
sharpener avatar image
sharpener answered ·

Two possible applications in a straightforward system are to

  • measure grid current where there are loads or PV connected on the input side of the inverter so the internal current transformer cannot be used
  • measure PV where it is connected to the output of the inverter so it will continue to work in a power cut
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matt1309 avatar image
matt1309 answered ·
Hi @P. Rogalski


You can use a ct clamp in place of energy meter on the incoming tails.

The energy meter needs to be before all the loads you want victron to know about/cover.


So in your example doing grid->consumer unit -> energy meter is fine as long as all of the loads/circuits are connected on "behind/after" the energy meter

ie grid-> consumer unit -> energy meter -> RCDs/breakers/mcbs for each circuit in the house.


If electrician opts for this route they'll probably do.

Grid-> Consumer unit -> energy meter -> main switch -> RCD -> mcbs.


(from main switch onwards would be normal consumer unit setup)

They might add another main switch before the energy meter. The physical location of the meter doesnt matter ie inside or outside a consumer unit. It just needs to be before (infront of) the loads. An electrician will know this though so you should be good.




2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.