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mdk avatar image
mdk asked

Energy Meter ET112 using batteries to heat geyser

Hi there,

I have a Victron PV system powering my house. Originally I had this system without the ET112. I am allowed to push back into the grid so I wanted to monitor what is coming in vs going out and I wanted it to be integrated into the app - for ease of use. I asked my installer about the ET112 and he said that this would work for my purpose.

Once the ET112 was installed we run into an issue but first, my setup is pretty simple:


victron.png

The only thing on my AC Loads is my geyser, the rest of my house is on Critical Loads - which is fine. (I have gas everything except geyser)

If I turn my geyser on you can see the load is taken from my inverter:

victron2.png

Only after the ET112 was installed did this start happening. My problem with this is obviously at night and in the morning my geyser turns on and it draws from the batteries which chews through my batteries.


My installer is saying that there is no way to have this ET112 just work as a meter and not divert the power from the batteries or PV to the AC loads. He wants to install another 3rd party meter in-front of the ET112 and have the geyser behind it so it isn't aware of it. (Take note I am not 100% clued up on these things - sorry if I don't use the correct lingo.)

I just thought I'd ask the question here as this really does not seem correct to me - how can a smart meter divert power like this and how can it not be capable to disable that? I just want it to tell me how much goes into the grid vs comes out of the grid.

Thanks for the help in advanced.


Parts list:

  • Venus GX
  • MultiPlux-II 48/500/70-48
  • 2x BSL Batt
  • SmartSolar MPPT VE.Can 150/100 rev2
  • Energy Meter ET112
Multiplus-IIVenus GX - VGXEnergy Meter
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3 Answers
wkirby avatar image
wkirby answered ·

If the geyser circuit is wired after the ET112 then the system is trying to power all loads after it by attempting to make the grid meter read 0W. It is a control loop. This is the intended use of grid meters within the Victron system. Meters are assigned a selection of roles to form control loops.

If the geyser circuit is wired before the ET112 then it will not take energy from the battery because the geyser current will come straight from the grid and not through the ET112.
In this arrangement, you'll not se the geyser power readings and also the -3445W reading will not be true grid power when the geyser is heating because the geyser will be taking this excess PV power, but you won't see it.
Adding another meter before the geyser circuit (third party meter - geyser - ET112) will show the true grid power, but this would be an arbitary meter which would not be able to be integrated into the Victron system for viewing as it would not have a specific role to be assigned to it.

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mdk avatar image mdk commented ·
So in other words my installer sold me the wrong device. All I asked him for was a smart meter that could hook into the virctron system that I could track in/out grid electricity with. He never mentioned that it would try to grid meter read zero.
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wkirby avatar image wkirby ♦♦ mdk commented ·

@MDK
My answer above is not wrong, but my colleague has informed me that there is a much better way. No wiring or alterations needed.

Simply go into ESS settings and change the "Grid Metering" option from "External Meter" to "Inverter/Charger"
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This effectively bring the metering of the grid energy back to the MultiPlus / Quattro. Loads inbetween the ET112 and the MultiPlus / Quattro will not be powered from battery and the red box will show true grid usage reflecting the amount of grid energy used to power the geyser. Excess solar will power the geyser in the afternoon and the difference required will come from the grid and show in the red box.
EG. 2KW excess PV will show -2000 in the red box if the geyser is off or fully hot and 1000W if it is heating (assuming your geyser is 3KW).
In the early morning the red box should show 3KW if the geyser is heating without any excess PV.

That's worth a try for no cost and very little effort.
I tried it with a 100W (old school) lightbulb from a biltong box and it seems to work for me.

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mdk avatar image mdk wkirby ♦♦ commented ·

I don’t want to break anything so what’s the worst that could happen by doing this? Change it to PV inverter yes?





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wkirby avatar image wkirby ♦♦ mdk commented ·
Don't alter that setting. Leave that setting as "Grid meter". Just change the setting in ESS menu that I showed earlier.
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solarhack avatar image
solarhack answered ·

Hi

The ET112 doesn't divert load, its purely a meter but it does feed power information to the inverter so that it can control its power generation across split loads.

In a system with no meter the Inverter generates power based on demand on the Critical load ACOut connection. The inverter then powers that connection and controls the grid and DC (battery and solar) to enable provision to the loads and charge the battery (if required).

In a system with a meter or current transformer that is placed between the grid and the critical/non-critical input split, the Inverter will use the Meter to calculate the total load across critical and non-critical circuits. It will then provide energy to both, through the critical ACOut and the ACIn.

In order to stop powering the water Heater/Geyser you would have to either remove the ET112 or move it to monitor the Critical circuit only (This however doesn't make much sense as the inverter is probably more accurate and responsive than the meter ). If you want to get the total power consumed by you across this set up you would have to add another meter in front of the load split. This meter however wouldn't integrate with the Victron portal or inverter and would need to be monitored seperately.


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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

With the MY-PV AC-Thor you could send surplus energy into the heater.
https://www.victronenergy.com/live/actor_ess

I think with Node-RED you could activate the relay of the Venus if you feed-back X watts.
https://community.victronenergy.com/questions/73741/venus-os-large-node-red-and-signal-k.html

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mdk avatar image mdk commented ·
Thanks for this.
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