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jaro2k avatar image
jaro2k asked

The best setup for Zero-feed-in 3-phase installation using Fronius inverters.

Hi,

I would like to ask for your opinion. We have 3-phase power grid connectivity in our building and we are considering building a system based on Victron ESS using 3x Multiplus-II 5k in combination to Fronius inverters connected on the AC-in side. Since there is Zero-feed-in requirement from the energy provider I would like to ask what would be the best solution to eliminate energy feed-in on any of the given phases.

Sure, we plan to install energy-metering on the grid-input which will communicate this to Cebro-GX.

The alternatives are:

1/ using 1x Fronius Symo

2/ using 3x Fronius Primo (single Primo connected to each phase)


I have a feeling that second alternative could provide better results in terms of zero-feed-in requirements just because energy consumption in the building is asymmetric so if we set "Multiphase regulation" to "Individual Phase" then ESS logic will likely manage each Primo inverter independently based on consumption per each phase to keep Grid-setpoint Zero for each phase.

The first alternative on the other side may lead to ineffective use of Symo inverter since this device would distribute power across all 3-phases symmetrically regardless of asymmetric consumption which could result in lowering the power generation on Symo based on phase with lowest consumption.

What are your thoughts?

Thanks

ESSFroniusfeed-in limit
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7 Answers
Duivert NL avatar image
Duivert NL answered ·

Hi, I dont think you can control zero feed in with fronius inverters on AC in side, only on AC out side of the multiplus

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max-payne avatar image max-payne commented ·

That is not true in three ways.

First fronius support zero feed in via Fronius Smart Meter
Second fronius can be controlled via frequency shifting by multiplus-ii
Third a fronius can be controlled via lan by the cerbo GX

https://www.victronenergy.com/live/ac_coupling:fronius
https://www.fronius.com/~/downloads/Solar%20Energy/Technical%20Articles/SE_TEA_Quick_Guide_How_to_set_up_Export_Limiting_using_the_Fronius_Smart_Meter_EN_AU.pdf

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Duivert NL avatar image Duivert NL max-payne commented ·

Of course fronius support zero feed in, i did not state that :)


Yes, can be controlled by frequency shifting, but not on AC in!

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max-payne avatar image
max-payne answered ·

In your system it would be recommended to put the controlled PV to the ac-out of the Multiplus. If that is not possible because of the 1:1 rule or cost - then the fronius side needs to control itself:
BOM: Fronius Smart Meter TS 65A-3


A real important point of your system is if your are grid parallel or grid serial with respect to the 3x Multiplus II.

I assume grid parallel now. This way frequency shifting cannot be used and you have to go LAN route. https://www.victronenergy.com/live/ac_coupling:fronius


IMO you invite a lot of headache by mixing this. You have two easier options:
Buy a fronius hybrid inverter and a matching battery and a TS 65A-3 OR
Buy 3 multiplus-ii and a (pylontech) battery and a Victron Smartsolar and a EM24.
Both ways support zero-feed-in


Better yet - make zero feed in go away and make money with excess

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Duivert NL avatar image
Duivert NL answered ·

There is more info here, part 2.1.3 and 4.3.14:

https://www.victronenergy.com/media/pg/Energy_Storage_System/en/index-en.html


Also why you cant use a fronius smart meter with ESS, see Q4 here:

https://www.victronenergy.com/live/ac_coupling:fronius

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jaro2k avatar image
jaro2k answered ·

Hmm.. right, frequency shifting will not work on AC-IN but I could control all Fronius inverters via Modbus-TCP.. so I believe I could still stay with Victron Cebro-GX and Victron compatible smart-metering on grid-input. Don't you think so?

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Duivert NL avatar image
Duivert NL answered ·

Yes it should work, but as @Max Payne said it will give you headache’s

Connecting them on ac out (if possible) is much easier and you will benefit from still working solar when grid is lost!

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Petr P avatar image
Petr P answered ·

@jaro2k Have you manage to zero feed in? With fronius via modbus tcp control on AC in? In ess setting?


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jaro2k avatar image
jaro2k answered ·

I'm about to try and find out whether it works.. give me a few more days.. FV pannels are already on the roof right now.. and I'm waiting to get remaining fronius inverters.. I will let you know..

It's going to be 60kWp installation with 6x Primo 8.2 + 1x Symo 10.0 connected in AC-IN of Victron ESS system (1x MP-2 5k) using Victron Smart-Meter + CT (250A/5A).

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