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jgrimm77 avatar image
jgrimm77 asked

Voltage swell on Victron/Fronius 3-phase system

We have a 3-phase installation comprising:

9x 15kVA Victron Quattro

9x RS450 Victron MPPT

3x 20kVA Fronius Symo

314kWh Solar-MD battery


When the grid fails, we often experience voltage swells for between 20 and 90ms on the output. The highest so far (measured with a Fluke 434) was around 277V!!!


The above is only observed when the Fronius Symo units are in production.


We have followed the relevant guidelines for Fronius integration and double-checked the settings several times.


Any suggestions will be appreciated.

MultiPlus Quattro Inverter Chargervictron communityfronius symo
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Mike Dorsett avatar image Mike Dorsett commented ·

if you can get at the grid settings in the Fronius, you could try reducing the Overvoltage disconnect settings, usually there are three thresholds which are time and voltage dependent - these are usually automatically configured when the country code is set, but may be able to be tweaked in expert mode.


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ikati avatar image ikati Mike Dorsett commented ·

Hi Mike, Thanks for the suggestion. I work with @jgrimm77 on this one. We've got it set up as MG-50 for victron, and i can't see any way to get to expert mode from the web interface of any of the three symo's.

Any pointers to access expert mode? we do have the service password, but that only gets us do DNO settings.

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1 Answer
Paul B avatar image
Paul B answered ·

I would suggest that you look at the frequency when you get the over voltage.

Depending on setup , however frequency shift is usually used to control the PV inverters and thus tells them to derate for this to happen then you must install assistants in the multiplus units to control this. so read up on this in the victron setups


I suspect that your batteries are full and the grid is off, and if the solar is still outputting then the system has two choices, increase battery voltage or AC voltage or both. as the solar power has to go somewhere. normally it would be sent back out to the grid.


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