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phatjoe avatar image
phatjoe asked

Multiplus II ESS using Grid for Essential Loads even when PV & battery available

So confused what is happening right now. We have load shedding regularly in South Africa and recently my system has been doing something super strange. After a load shedding cycle (when the grid is back) - it starts using the grid to charge the battery up to 100% (even though the battery level isnt below the minimum SOC level). Once it's done with that it then starts using the Grid power to power the Essential Loads even thought there is plenty of PV and battery power available to supply these loads. The other confusing this is that whilst it is charging my battery and proving my essential loads from the grid my grid meter doesn't reflect this usage at all. It only reflects around 45watts of usage while I know it is drawing far more as I can see it drawing 1.5kw when I check under 'Remote Control' the AC-In stats under the Multiplus.


Strangely, if I then turn the Multiplus itself off and back on again, it resolved the issue and everything starts working as it should. That is - until the next load-shedding event - then it goes back to the strange behavior again (until I again power the multiplus off and on).


System:
Multiplus II 3000/48

ET112 Grid Meter

Pylontech UP5000

Assistants - ESS

Minimum SOC - 35%


I have a suspicion that the ET112 might be wired incorrectly. Just don't understand how that could lead to this behavior if it is? If someone could please let me know if this behavior makes sense in the scenario of the ET112 being incorrectly wired I would be so grateful.


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Multiplus-IIESSEnergy Meter
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2 Answers
nickdb avatar image
nickdb answered ·

Disable the meter in the GX, the problem should resolve, then you can work the rest out afterwards.


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phatjoe avatar image phatjoe commented ·
Thanks - will try that when it next occurs. Does the described behavior make sense to you as being symptoms of an incorrectly wired ET112?
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phatjoe answered ·

Pleased to report that this issue has now been resolved. Pretty chuffed to have found the issue and been able to resolve it myself.

Issue was indeed that the energy meter had been wired incorrectly by the electrician. He had installed it in such a way that power from the MBR was running through the ET112 and then onward to the loads (which is correct of course). Trouble however, was that this was the case for all loads other than the inverter grid feed breaker on the non-essentials side. This breaker had been installed with it's live coming directly from the load side of the MBR (two wires from the MBR load, 1 to the ET112 and the other to the Inverter Grid Breaker) and as such, this load was being excluded from the energy meter reading as the path of least resistance was directly from MBR -> Inverter Breaker.

This wiring issue resulting in the Inverter struggling to achieve it's configured grid set point at times when there was little / no load on the non-essentials side. The result is that the Multiplus would drop it's resistance more and more in an attempt to draw power from the grid and achieve it's set point, but no matter how much it did this no reading would ever confirm it had achieve it's goal. As such it would draw more and more power from the grid and this would end up feeding the battery and the essential loads.

After correcting the wiring of the ET112 such that all loads (including the inverter grid breaker) were going via the ET112, the issue resolved. Pleased to report the system is now going like a boeing (not the 737 max, more like a 747).

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