MultiPlus-II AC-coupled Fronius

Hi, does MultiPlus-II have the ability to control Fronis power other than frequency, e.g. TCP/IP, RS485, etc.? Frequency control has a slight hiccup on home appliances.

Hi @m2teusz,

The parameters (such as Voltage, Frequency, Phase Angle, etc.) between the Fronius and Multiplus-II must match for the Fronius to provide power. If the parameters do not match, the Fronius will not supply any power.

You can configure the Multiplus-II frequency via the ESS Assistance, as explained in the link below: AC-coupled PV with Fronius PV Inverters [Victron Energy]

Additionally, a GX device like the Cerbo-GX is required as a communication hub between the Victron and Fronius systems.

The thing is that I don’t want to control the frequency because the home appliances (hotplate) don’t work properly in inverter mode with Fronius on and increased frequency. I have Cerbo and I want the PV power to be regulated e.g. via modbus.

As far as I am aware the fronius needs the frequency shifting. The modbus is for other info and also allows the PV inverter to be shown on the GUI. However it is possible to use the AC2 out to be the input from the Fronius but it would be a straight cut off not a gradual modulation of the power supplied.

Frequency shifting only happens when offgrid.

Are you grid connected? (Cant trust the tags as not everyone is diligent with them)

There are other ways to do it but it is a bit more complicated.

Yes, the frequency change takes place in off-grid mode when PV reduction is necessary (battery full, no reception). Can you tell me what these methods are, because my wife will throw me out of the house :wink:

I have been trying a node red flow recently (it hasn’t totaly removed all the frequency shifting i still get some)

Since i have dc mppts and the fronius
It uses the energy meter reading loads and uses the power limit on the fronius to throtttle it down balancing power from the fronius and mppt

Hi,
I have a M2 Plus, Cerbo GX and Primo 8-2.1 on AC1 OUT and ESS.
The Cerbo control my Fronius with Modbus TCP. My feedin is config to 3kW. When the cerbo detect this value, it communicate with the fronius to reduce the production.
You need to config the fronius with modbus TCP priority.

Can you send me the flow from node-red? Or write what node you used (a photo of the flow would be appreciated)

But then you are connected to the Grid? If so, the frequency is taken from the Grid and MP-II does not modulate it. I need to reduce without connecting to the Grid ;-( without changing the frequency.


I think it will work, thanks for the suggestions :wink:

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