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Philip Kamau avatar image
Philip Kamau asked

Single-phase Fronius inverters in a three-phase Victron system

I am considering using single-phase Fronius inverters in a three-phase Victron system instead of a three-phase Fronius inverter. This decision primarily stems from the availability of two single-phase Fronius inverters that I currently have, and purchasing a third would be more cost-effective than buying an entire three-phase Fronius inverter.

I am seeking insights from those with experience in similar installations, particularly regarding the frequency and phase control mechanisms employed when integrating a single-phase Fronius inverter with a three-phase Victron system. How does the system maintain synchronization under varying load conditions?

Additionally, I am contemplating whether it might be better to disregard the Fronius inverters (which I intend to connect on the AC1 Out and program the system on ESS) and instead utilize MPPTs.

Any guidance or advice based on your experience would be greatly appreciated. Thank you.

MPPT ControllersESSFronius
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Philip Kamau avatar image Philip Kamau commented ·

AM also worried of the potential implications on overall system performance and reliability when mixing single-phase Fronius inverters with a three-phase Victron setup.

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Michelle Konzack avatar image
Michelle Konzack answered ·

Thee should be no problem with a Fronius Primo on a 3-phase Victron System.


I have done this in Estonia, where a Customer had only a 230V/32A Grid connection and we had only a Fronius Primo 7kW connected.


Last year he got a 3-phase upgrade from the Grid-Provider for free (Aluminium Over-Land cable to a Earthcable) and we installed 4 MultiPlus-II 24/5000 (one phase has two) and continue with the Fronius Primo without problems.

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delf67 avatar image delf67 commented ·
The question was not about 1 single phase Fonius, but three and how they interact when one phase is maxed out.
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Philip Kamau avatar image Philip Kamau commented ·

Thank you for the feedback, Konzack, am guessing you kept the Primo on the phase with an extra Multiplus. Am thinking of not synchronizing the single phase inverters if I choose to connect them on the input and maintain the independent meters on each phase.

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Paul B avatar image
Paul B answered ·

there should be no issue using one of those single phase units on each phase making 3 used in total. as long as you are using frequency shift to control them and that they are correct setup. make sure you test at the freq increases when there is no grid and that the batteries are full - just so you know they will shut do if the need arises.

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Philip Kamau avatar image Philip Kamau commented ·
Thank you Paul for the feedback.
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