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johanh avatar image

Quattro 10kva 3phase system - Swells and dips over 10%

*****System: Off Grid

3 x Victron Quattro 10kva

1 x Fronius 10kW Symo - 1 x 20kW Symo

18 x Pylontech US 3000

2 x Skylla 48v 50ah AC chargers ( Supplement charge for batteries )

84 x 410w JA Solar Mono half cell


System was installed on new build home. We experienced dipping in the lights. The electrician has done a logger test last week and the results are a bit concerning. Lowest dip recorded was 180v ( 10 - 60 milliseconds), and it regularly dips below 10%, 207v.

Highest swell recorded 257v (10 - 60 milliseconds )

Attached logger data and Victron data ( 1 min intervals )

AMSO 1216 JNF Electrical.pdfHuis Visser Statistics for week 21 May to 28 May 2021.pdf

L1 (Victron) - Phase B (Logger Test)

L2 - Phase C

L3 - Phase A

The underfloor heating runs on Phase C (L2). It switched off on Tuesday morning and technicians are coming in to have a look.

My question is, has anybody experienced a similar situation? Is there a way to minimize the shifting?

Thank you


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Update:

* Results of second test. First 36hrs main DB incoming 3 phase line from Off grid system. Last 36hrs directly on Victron output and termination boxes. (This was done to check that data corresponds and we have no other electrical problem in-between DB and Inverters.)

AMSO 1217 Test 2.pdf

Results are still the same.

*The underfloor heating has been fixed. Unrelated issue

* We have done a firmware Quattro's and N-E bond in the termination boxes. ( This was done before new logger test was done)

* Lights are more stable. Flickering only happens when sun is going down, load increases and the shift happens between Fronius not being able to supply sufficient power and the batteries taking over (100% SOC) I will follow up with Fronius to see if there is a fix for this. ( I have upgraded the Fronius to latest software)

* My question is: The fluctuations are very short in duration 20 - 40 milliseconds. On average we remain on 230V. I do understand being fully of grid will make the voltages fluctuate. Is this in normal parameters? Is there a way to minimize it? Will it have a negative long-term effect on household appliances?

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offgridvoltage3 phasefronius and victronfronius off-grid
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This sounds and looks like an electrical problem downstream from the Victron install, or a very bad grid connection. Which setup are you running? Grid connected / ESS or other?

johanh avatar image johanh Murray van Graan ·

Hi Murray

Thank you for the reply. I forgot to mention the system is off grid. There is a single phase 60A connection, only used to supplement charge the batteries at night.


We have done a firmware upgrade and a N to E bond after the Victron's in termination boxes. Since Friday I have put on another logger on main DB to check if there is any difference. On Sunday I have Switched the logger directly onto the Victron's to see if there is a downstream problem. ( DB is about 8m (conduit) away from system)


I will post results tomorrow.

2 Answers
tozz avatar image
tozz answered ·

You say the system is off-grid and only the Skylla chargers are connected to the 60A line. Yet, the metering is done on that 60A line, correct?

If the issue is at the Victron's output (where the house is connected too) why was the measurement done at the grid connection which is only used to power battery chargers?

In general.. any off-grid system will be prone to voltage fluctuations, considerably more than any grid connected system. It was the primary reason why I opted for a grid-connected setup.

If eg. a water heater is instantly going from 0W to 3 kW powerdraw, the inverters need some time to increase output power. So in any off-grid system where there are power hungry appliances turning on and off, you will have voltage fluctuations.

This includes heaters, boilers, dishwashers, washing machines, dryers, fridges, freezers.. Basically anything with a heating element or a motor.

In my own situation it's even worse.. I have a heatpumpt that can use up to 9 kW for 'booster heaters', which turn off and on instantly. I also have a Tesla, which does increase charging power slowly (it increases amps at around 1amp/second), but it does instantly disconnect. So it can go from 17 kW to 0W in the blink of an eye.

Those instant big changes in power draw will definitly have a great impact on your voltage.


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Hi Tozz

Just for a bit of background, the owners bought a property and demolished in and built a complete new home. The original connection is 60A single phase. Getting a new 3 phase line laid by the utility was very expensive and they opted to go off grid. The second reason for going off grid was, in South Africa we are hit by rolling blackouts, called load shedding. and the client wanted uninterrupted power.

The 60A single phase is only used on the two Skylla's as supplement charge during the night. Consumption drops to about 3,5kWh after 22h00 and the Skylla's carry the load and charges at about 24A. The house is power hungry due to heat pumps, walk in fridge, AC's, underfloor heating ect. Consumption last month was 4100kWh.

I agree that the instant power demand of a large motor will make the voltage drop seeing the inverters need to ramp up to carry the increased load.

The first logger test done, was in main DB incoming 3 phase line from inverters. We have now run a second test for 3 days, first 36hrs was the same as test 1, last 36 hrs directly on Quad output and termination boxes. I have done this to make sure data matches and to check if we had any other electrical issues on the lines ( Main DB is about 8m away through conduits) I have posted the new results.

The biggest concerned for me is, will the fluctuations have a negative affect on home appliances over the long term?

tozz avatar image tozz johanh ·

The fluctuations will have some effect on longevity of appliances. The electronics will have to cope with all the fluctuations. How much it will effect the lifespan, I can't say. It will probably depend on the quality of the device.

I have a fully grid-connected system, but even I have an issue with *some* lights flickering. I'm using Philips LED lights everywhere. Most of them are GU10 but I have some E24 'big bulbs' as well, those flicker. A lot. But not always, but enough to be annoying. The GU10's do not flicker at all. Never.

You might simply try another brand of lights. If that doesn't help you might consider running 12V LED lighting. That's usually more stable as it doesn't have to cope with distorted sinus waveforms


Paul B avatar image
Paul B answered ·

Suggest that you try changing the low AC disconnect from default 180v to say 210v and then the quattro will disconnect from the grid at 210v. currently its following the grid up down to 180 volts or the high side then disconnects and you then see the lights brighten as it quickly changes back to inverter voltage setting 230 volts as the Quattro is supplying the power after the disconnection until the grid power voltage raises to its reconnect setting.

The quattro ONLY controls the output voltage when the grid is disconnected.

it does not have the power to over ride the grids output voltage.

also any one phase dropping voltage will cause all 3 phases to disconnect and run off the batteries.





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Hi Paul

Thank you for your response.


I forgot to mention the system is off grid. We only have a 60A single phase line that runs the Skylla chargers. Not sure if this setting change will help seeing the Quattro's have no grid connection.

I have posted on Murray's answer what our steps was this last week and will post results by tomorrow.