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Warwick Bruce Chapman avatar image
Warwick Bruce Chapman asked

Understanding Overload Warnings on Multiplus II when loads are connected to AC2out instead of an Energy Meter

I have the following configuration:

  1. MultiPlus II 48/3000/35-32 (2628)
  2. 8 x Lead Acid 105Ah
  3. Battery Balancers
  4. Octo GX
  5. 2 x 100/35 MPPTs
  6. 12 x 270Wp panels in 2 banks of 2 parallel strings of 3 panels in series

I have critical loads on AC-Out-1 which include the lights and plugs of the house - usually around 500W. I will soon be adding the circuit for the washing machine, tumble dryer to AC-Out-1 circuits.

I have the two geysers on AC-Out-2 which peak around 5-6000W.

The oven circuit is not on the Multiplus, fed by mains only.

I do not yet have an energy meter or BMV installed (I have them but need to install).

I am running ESS on Keep Batteries Charged and Feeding In.

My decision to move the geysers onto AC-Out-2 was informed by the MultiPlus manual which insists that the loads on this output are fed from the mains up to a maximum of 32A and that over and above that, the inverter can supply a maximum of 13A sustained to loads on AC-Out-1, bringing the total maximum to 45A across the two AC-Outs. I did this before I enabled Feed In because I wanted the MultiPlus to use as much of my PV as possible to serve loads in the house (3240Wp).

So, I am curious as to why I get overload warnings on a daily basis, often to the extent that VRM suspends the warnings.

Is it possible that the overload warnings have nothing to do with the geysers on AC-Out-2 but rather with the PV generating more than the +-2400W maximum power of the MultiPlus? Though I am pretty sure the warnings only started after I moved the geysers to AC-Out-2.

I know that when I install the energy meter (ET112), I can move the geysers off of AC-Out-2 and back onto the main DB to the right of the ET112 but as a matter of interest and understanding the devices, I want to know what is wrong in this configuration.

Finally, I can share my VRM link but please not that in the last few days I changed my Venus Pi to an Octo GX (thank you Victron South Africa) and the downside of this change is that the device ID of the MultiPlus has changed and all the history of warnings are not visible in historical graphs. It would be nice to be able to choose to merge historic data with new device IDs. This is the case with the MPPT history as well - change USB port and it shows up as a new MPPT cc @Guy Stewart (Victron Community Manager).

https://vrm.victronenergy.com/installation/34733/advanced

Multiplus-IIVRM
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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Overload warnings are just a warning.

It is not yet an alarm leading to the shutdown of the system.

So putting a very large load, that you know is excess of the capacity of the inverter will lead to overload warnings.

As the system is also connected to the mains, once the inverter reaches it's limit, it will provide the rest of the power required from that.

There is no misconfiguration here as such. If the very large loads were instead visible to the inverter via the energy meters, instead of directly connected via the AC2 output, I expect the overloads warnings would stop.

In that configuration, the power demanded by the load, would be primarily supplied by the grid, and after a second or more, then the inverter would push as much as it was able to, but no more.

As it is now, the response to the load is much quicker, which the inverter will provide with priority, and then back off only once it hits the overload threshold (and the rest of the power required coming shortly thereafter from the grid).

It will be interesting to see if the reality matches the theory in this exact case, so please report back once you reconfigure the system to include your energy meters.

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Warwick Bruce Chapman avatar image Warwick Bruce Chapman commented ·

Thanks Guy. I will do so.

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Warwick Bruce Chapman avatar image Warwick Bruce Chapman commented ·

Hey @Guy Stewart (Victron Community Manager)

I'm pretty sure I understand what has been happening here - and it has nothing to do with the geysers on AC Out 2. This should have been clear to me because the overload warnings only ever happen during the day and not at night.

I believe this thread has the answer, which is that in peak sun, my panels are generating more energy than the multi can invert, so we get the overload warning. I believe that since I upgraded the MPPTs to 1.47 the MPPTs now back off to reduce the likelihood of the Multiplus overloading on solar: https://community.victronenergy.com/questions/39185/pv-sudden-dropoff.html?childToView=39210#comment-39210

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samduncan avatar image
samduncan answered ·

Hi @warwick


Super useful post of yours :) I'm looking to do a setup very similar to yours and want to understand what's the advantage of using the current sensor to move the geysers off AC2 and onto the DB? Is it just that you'll be able to have a total load > 45A?


Thanks

Sam

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Warwick Bruce Chapman avatar image Warwick Bruce Chapman commented ·

Hey Sam


Don’t know what you mean by current sensor here. Can you clarify?


Since this post, I have the ET112 energy meter installed and I do not get overload warnings anymore. But I do believe that it could well have been the MPPT upgrade that fixed the situation.

Explain in more detail what you’re trying to do and I will do my best to advise.

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