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Bobby avatar image
Bobby asked

ESS + Multiplus II + ET112 = backfeed?

Good day all,

So living in South Africa, any amount of backfeed causes our utilities "Smart" meters contactor to trip and disconnect the utility grid.

I have 12x330W solar panels and 48V battery bank. Every now and then I did see some small backfeed even though the option to "Feed-in in excess solarcharger power" is disabled which tripped the utility meter and they had to come out and reset it in order for it to work again.

I setup in my ESS Grid set point to 60W just to have some kind of pull and I am not too happy to increase that further.

Very simple question - would installing ET112 Energy meter between the utility "Smart" meter and my Multiplus II prevent backfeed to the grid?

Multiplus-IIESSEnergy Meter
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solarhack avatar image solarhack commented ·

I have a question. Are you on a prepaid meter. The South African prepaid meters will trip if their is any feedback.

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4 Answers
Paul B avatar image
Paul B answered ·

It would give the Inverter better control and thus should help stop the small issue. but I would NOT guarantee it in any way shape or form. I myself have not tested it to that fine a level.

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laurentiupitran avatar image
laurentiupitran answered ·

Hello,

there is not ZERO feed in a ESS system; this is truly impossible, as it was marked out in few posts till now.

More of this if you have in your home as load some devices as ironing machine for clothes press, some washing machine that need to heat up the necessary water or a heat pump, you will have more injected energy in the grid, even you set ZERO injection.

Practically, switching continuous necessary power from an ESS system is making this one to need more time to regulate the power as the result is injection on grid....

attached you can see the graf for today in my ESS system '; counting this energy it is a sum of 2,08 kW for today....

There is another aspect for this energy that is injected on Grid: during day, when is enuff sunny on sky don t have much importance for me, but during the time that i use energy from battery is a BIG mess - hope that can be corrected in time.

Just added in -now is second from top- of this post the record of injected energy in grid for each phase.

Just for information, i will add a new graph that will show the energy injected on grid per each phase( is the same of the previous one, that it was total, now per phase ) in the same time it will be the energy for each phase for the load at that moment, that is particularly a expresso machine. This is FIRST from top graph.


example.png (84.8 KiB)
example-2.png (114.2 KiB)
example-3.png (100.1 KiB)
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Bobby avatar image
Bobby answered ·

Is there any device that I can get in order to achieve no backfeed?

Or maybe any other config besides ESS that can achieve it?

This is a really big problem in South Africa, as my grid meter will keep tripping :(

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Kevin Knoop avatar image Kevin Knoop commented ·

Hello from South Africa. The fix here in SA is to replace your pre-paid meter with one that's less sensitive. The one I installed last year works fine (Cape Town).

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suttridge avatar image suttridge commented ·

Also from SA. If you can, ask to have a Landis+Gyr pre-paid meter installed - but not the smart-meter type, only the standard pre-paid meters. I have an installation with a MultiPlus II 5000, which I have installed first in one property, and then in another. Each time, I asked for the L+G pre-paid meter to be installed. In each case, the ESS was set to not feedback, and the ESS grid-point setting was just 10W. Although the regulation of the MultiPlus is not good enough to prevent **any** feedback, these meters will tolerate a certain amount.

[Full disclosure - I used to work in software for L+G for 30+ years until retirement end of last year. The way the standard L+G pre-paid meter works, is to accumulate the reverse power, and if it exceeds the accumulated limit, then it will trip. But any forward power reduces the accumulated reverse power, so generally, you are always on the "good" side of the meter's limit. For example, if you have 20W reverse power for say 10 seconds, the meter won't trip yet, and then if you have 20W forward power for longer than 10 seconds, it will wipe out the reverse power measurement. I am not sure what the actual accumulated limit is, but I have never had mine trip for this reason at all. Most other pre-paid meters (and I think, the smart meters) measure the instantaneous reverse power, instead of the accumulated reverse power, and thus they tend to trip much faster.]

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Karl Möller avatar image Karl Möller suttridge commented ·
Hi, do you know if this has always been the case? I have a Sabre SA-SA012 (seems from 2006) and want to know if I should be concerned before installing solar (Eskom direct customer, nightmare to get meter changed or unlocked after tamper). Seems the newer models have register 035 that one can also check, but mine shows nothing for 035.
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Karl Möller avatar image Karl Möller Karl Möller commented ·
@suttridge sorry realised this is a very old post, so just a ping to see if this can alert you. (Running firmware 9.515 if that means anything, can't find a manual for this)
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suttridge avatar image suttridge Karl Möller commented ·

Hi Karl,

Since that old post, I have moved to yet another property, installed another full Victron system with MultiPlus II 5000, and also requested a Landis+Gyr prepaid meter to be installed. ESS again set to no feedback, and ESS grid-point setting at 10W. It works 100%, and I've never had the meter trip on reverse power at all.

As far as I am aware, my comments regarding how the L+G meters work are still valid. However, my meters have been the split-meter type, where the meter itself is out in the box in the road (or up on a pole in the road), and the CUI (Customer Interface Unit) is a separate small display thing on your house. It seems you have one of the single unit meter types (Sabre SA-SA012) containing breaker and display/keypad in one unit inside your house. A manual for this can be found at https://jknvenergy.co.za/wp-content/uploads/2022/01/Landis_Gyr_Cashpower_Sabre_Integrated_Dastasheet.pdf

I'm not sure if this older one reacts the same way as the split-meters do with respect to reverse power. So unless you can get that one exchanged with a L+G split-meter type, I cannot guarantee that the Sabre will not have problems with reverse power.

Regards, Steve

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Karl Möller avatar image Karl Möller suttridge commented ·

Hi @suttridge


Thanks. Seems the Sabre ED is slightly newer and has register 035 that one can inspect to see if tamper on SRE is enabled. Mine does not seem to have that register.


Tried contacting Dave Tarr at L+G but he only had the manual for the newer ED. Seems my older meter was also known as a Siemens Sabre around 2002/2003. I know the Sabre EDs work the way you described. They run newer firmware though, 12.x vs 9.x on mine.

Tried searching the a manual, but could not find anything for this specific one.

Guess I have to risk it and deal with Eskom Direct afterwards if something goes wrong...probably be without power for a week or a month.

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suttridge avatar image suttridge Karl Möller commented ·
Yup, I guess that one you have is quite an older one from when the company we worked for was still Siemens, before being taken over by Landis+Gyr.
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Karl Möller avatar image Karl Möller suttridge commented ·
@suttridge Hoping that Eskom resets my meter in case of tamper is terrifying, but I guess nothing left to do but risk it at this point. Maybe I am lucky and it's too old to reset or something and I can get a new meter. Eskom definitely doesn't just hand over new meters on request.
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Bobby avatar image Bobby commented ·

Hi guys,
I am in JHB....
I am going to apply for prepaid meter from City of Joburg. Do I ask them for Pre-Paid meter options or do they just come and install Hexing or whatever they prefer?

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solarhack avatar image
solarhack answered ·

Hi

Two things you need to consider. ,

  • The first is Exsolar have a device they claim can stop grid feedback (Never tried it but maybe its worth looking into) https://www.exsolar.co.za/uploads/8/0/1/3/80134398/smart_energy_controller_brochure.pdf
  • According to City power they are exploring allowing you to feed in and be paid for it and will have a policy by midyear 2021 (Lets see if that happens). They do state that prepaid meters will be excluded and only sites that meet the regulatory standards (Your Multiplus II does) as well as have a post paid meter will be eligible.


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Bobby avatar image Bobby commented ·

That device looks interesting...I'll definitely check it out, thank you!

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