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mkbrandt avatar image
mkbrandt asked

Unexpected grid feedback from Quattro 15000

I have a newly installed Quattro 48/15000 connected with an autotransformer to my house. I brought the grid to the AC in 2 terminals from the meter panel. The autotransformer feeds our house through a panel which has two feeds to sub panels. I also have a battery bank (30KWH EG4 batteries) and an MPPT 450/200 that has 10KW or panels attached.

The inverter has a loud buzzing noise that comes and goes as well as some noise on the AC waveform but this question is about the grid tie. When I throw the breaker enabling the grid connection I hear the relay click and the sound from the unit changes, all expected. What isn’t expected is that the cerbo display shows the grid connection at 50W or so but an additional 3KW of load that is not coming from the house. External measurements have shown this to be exported to the grid but the cerbo knows nothing about this. This even happens if there is no solar and all of the power is coming from the batteries. I have the grid set point at 50w and have turned off export from the dc and ac connected solar chargers in the ESS settings so I’m at at loss to explain what is happening. I can’t leave it connected to the grid when it exports against configuration. This means that if my batteries get too low I will be without power.

Maybe I have something misconfigured? Any ideas about how to fix this would be appreciated.

MultiPlus Quattro Inverter ChargerESSAutotransformer
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3 Answers
Alexandra avatar image
Alexandra answered ·

@Mkbrandt

If the quattro is not reading it as feedback (as in negative on the grid tile) then you have something in your wiring that is sending the power back.

Check your DB. It is not likely a config issue

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mkbrandt avatar image mkbrandt commented ·
I think you’re probably correct but I can’t figure out how this is happening. If I disconnect at the autotransformer the system appears to be ok. If the autotransformer is on but the breaker it feeds at the panel is off it still has the unexpected load. All of the current is going through the neutral lead from the autotransformer to ground. When the AC in is disconnected this doesn’t happen and everything seems to work. I’m a little stumped.
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fabien-d avatar image
fabien-d answered ·

I think that there is a bug in Venus OS 3.0. See my topic here : https://community.victronenergy.com/questions/209940/bug-venus-os-30-color-gx-feed-in-grid.html

And you can try to enable Feed In and set it to 0w. It works for me but i am not sure of the absorption sequence after that.

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mkbrandt avatar image mkbrandt commented ·
I tried this but it had no effect on my situation.
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rickc avatar image
rickc answered ·

Is this North America split phase power? Assuming yes because of the autotransformer.

If not, please disregard this post.

The Quattro 15000 is for European 230V, grounding must be carefully handled as its “Neutral” is not Neutral when using split phase power. The ground relay must be disabled. Make sure this is wired safely, or you could have load current running on your grounds!

If the neutral of the autotransformer is connected to the incoming neutral of your grid power (which is likely) you may be trying to balance split phase loads outside of your house depending on how your upstream power is distributed. Or more likely, loads inside your house that are connected before your panels.

However, you say the breaker to the auto transformer is off. Current has to flow through at least two wires, measure the ac current flowing through the autotransformer neutral and the input and output 240v lines. Is this a Victron authotransformer? make sure the input/output through the built in breaker aren’t flipped too.

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mkbrandt avatar image mkbrandt commented ·
I checked to make sure the line and neutral from the Quattro were wired to the correct terminals of the autotransformer input breaker and not flipped and they are as shown on a Victron wiring diagram I have (I.e. line to line, neutral to neutral). I also tried swapping them and that changed the character of the problem so that it showed all of the house load as feedback to the grid and zero load on the outputs. Odd result but I put it back the correct way. The autotransformer has an unbalanced output and if I disconnect all three leads of the output then the center tap is about 3.5v above ground. This may be due to some higher frequency noise on only the rising edge of the 240v output of the inverter. If I disconnect the neutrals from the panel to the house but leave the transformer connected the current does not happen. In this case it is still connected by ground and neutral to the meter so I don’t think the wiring before the inverter is at fault. I’m still stumped as to what is going on here.


The inverter noise and the distortion on the output waveform is enough for signature solar to conclude that the Quattro is faulty though and they are going to RMA it so we’ll see if a new inverter fixes the problem.

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