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fronius and victron

ESS with Fronius, problems with overload and AC2

Following setup : 3 x Multiplus 48/5000 II, 1x MPPT 250/100 , 1x Fronius Symo 12.5 and 2 x BYD 15.4

AC1 out and AC2 out are separated.

AC1 loads sum up to 10kW and AC2 loads sum up to 10kW max

We have been observing 2 problems :

1. Approximately every 7 or 10 days we encounter this problem. During daylight, while Fronius is producing 2-3 kW, and system is working with reasonably low loads under ESS batterylife, suddenly one of the phases gives overload alarm and system shuts down. We ask the household, they say nothing of high power was being drawn that moment.

2. During ESS, now and then AC2 output is disabled, although there is grid on the mains.

Following my observations :

This overload situation or AC2 output disabling never happens when system is in passthru mode.

Overload situation seems to happen while Fronius is producing, could it be that due to sudden clouds, the pv production makes a dip and then the multiplus try to invert that missing power ? which is then too sudden and causes overload ?

AC2 disabling : could it be that during ESS AC1 and AC2 are being regarded as one output and as soon as the total load of AC1 + AC2 goes higher than 15kVA AC2 is being dropped ?

What are your suggestions to debug these problems ?

bulraydin asked
thomasw-1 commented ·

2 Answers

Fronius Primo GEN24 Plus integration?

For the Victron guys:

I see that the Fronius Primo GEN24 Plus will be available in 2021. Has there been any integration testing done on this unit and is it something to consider over the current Primo models? My plan is to add a PV Inverter sometime this year so I might as well go for the new GEN24 unit if it has been certified by Victron. I won't use the Battery connection feature but I like the Active Cooling as my kit is in a warm environment already.

Quattro/VenusGX/Smart Solar Charger/LiFePO4 CAN Battery.



Ingo asked
alan answered ·

1 Answer

Fronius + victron feed-in during absorbtion

Hello and happy new year. I have a issue with zero feed in during absorbtion. My system is a fronius symo 8.2 with 1 multiplus 48/5000 connected on L1 AC out. When my pylontech batteries are in absorbtion the zero is not working well. I have setup the grid setpoint to 150 W but it keeps exporting arround 100 w. During bulk the grid setpoint is beeing followed. Can someone help?


mihaimicu asked
mihaimicu commented ·

4 Answers

is it possible to run a 1Ph PV inverter in frequency shifting on a 3Ph Victron Quattro system?


I have got an off-grid 3Ph 400V system comprised by 3x 15kVA Quattros and would like to install a Fronius 1ph Galvo PV inverter. Is this possible through the PV inverter support assistant? or mustit be a 3ph pv inverter?

Also, taking into account that for physicals reasons, there can not be modbus communication between the Fronius and the GX device, the system should work autonomously in frequency response.

Jesus Mazo asked
Jesus Mazo commented ·

1 Answer

Fronius Zero-feed-in option / Grid feed-in deactivation not working

Hi All,

I am wondering that ESS feature does not properly respect the deactivated "Grid feed-in" option.
In following screenshots you can see that the grid power flow deviates roughly between -2.000W and +2.000W, although it is not expected to feed-in anything.
Since I am not allowed to feed into the grid, I am forced to move away from ESS to actually deprecated HUB-2 application.

I would highly appreciate, if Victron could consider

  • a HUB-2 equivalent feature in ESS solution again and
  • assure that relevant energy is used mainly from battery and not from grid


  • grid power changing from +1.447W to -1.756W



  • grid power changing from +2.006W to -1.709W




Both configuration options aren't successful.



My environment

  • 3xMultiPlus-II 48/5000/70-50 in 3-phase (firmware 477) with a
    • ESS zero feed-in configuration
    • Multiphase regulation on single phase
    • Grid setpoint defined at 80W
  • Fronius Symo 6.0-3-M (firmware 3.16.7-1) – connected to AC-OUT1 (critical loads) – no additional smart meter - sunspec activated
  • Victron MPPT VE.can 250/100 rev2 (firmware 3.02)
  • PV modules all with absolutely identical direction and no shadowing
    11kWp in total: 6kWp on Fronius and 5kWp on MPPT
  • BYD LV 15.4 (allowed charging and discharging current during the test procedure 243A) - BMS connected via CAN-bus (firmware 1.16)
  • VenusGX (firmware 2.60) - currently 2.62-beta5
  • Any component with latest firmware as of today


thomasw-1 asked
thomasw-1 commented ·

4 Answers

Throttled Fronius wastes up to 90% of capacity - improvement required on Zero-feed-in

Hi All,

With this documentation I like to demonstrate that Fronius Zero-feed-in algorithm ignores up to 90% of available energy in a zero-feed-configuration, although all produced energy could be fed into battery at that moment.

@Victron&Fronius-Developers: Please read this article and translate improvements into next software releases.

Generic problem description

My PV panel power balance between MPPT-fed and Fronius-fed energy ratio is about 45% vs. 55% (my complete topology is described below). This screenshot demonstrates that this ratio can be also effectively generated and loaded into AC-IN and battery as long as the grid is disconnected from MultiPlus-II.


Only 30 seconds before when grid was still connected, I took that screenshot. You see that MPPT has nearly the same output, but the Fronius delivered only 28% of its actually currently possible capacity. Since the previous screenshot was taken before, it demonstrates clearly that at that moment there was no restriction of the battery taking additional energy (charging limit of 242A current allowed by BYD at that moment of time).


Frist conclusion
Fronius Zero-feed-in feature in Victron ESS wastes plenty energy (>75% in average – up to 90% in peak)

Closer analysis
Following analysis demonstrates that Fronius Zero feed-in mechanism only works as long as you have a steadily deviating power consumption. Otherwise it wastes plenty energy.

1. AC load on AC-OUT consumption is currently low at 249W and Fronius feeds in with 934W only (compared to screenshot in step 3 you see that was is only 50% of the available capacity at that moment).


2. Switch on a mentionable load on AC-OUT1 activates the Fronius within a few seconds to leverage full available capacity.


3. After having switched off the additional load, Fronius continues to produce similar but already slight lower volume. The produced capacity is fed mainly into battery.


4. As long as there is no peak any more on AC-OUT1, Fronius lowers its production steadily down. In that example its returned to 23% of currently available capacity.
Battery SOC was 52%, the currently applied current 52,9A with readiness to take 242A at that moment.


Please improve zero-feed-in feature so that also battery will be effectively loaded with available capacity on Fronius attached PVs.

My environment

  • MultiPlus-II 48/5000/70-50 in 3-phase (firmware 477) with a ESS zero feed-in configuration
  • ESS zero feed-in configuration
  • Multiphase regulation on single phase
  • Grid setpoint defined at 80W > currently returned to 60W again
  • Fronius Symo 6.0-3-M (firmware 3.16.7-1) with 6.030 kWp attached (55% of total PV) – connected to AC-OUT1 (critical loads) – no additional smart meter - sunspec activated
  • Victron MPPT VE.can 250/100 rev2 (firmware 3.02) connected via VE-Bus with 5.025kWp attached (45% of total PV)
  • PV modules all with absolutely identical direction and no shadowing
  • BYD LV 15.4 (allowed charging and discharging current during the test procedure 243A)
    BMS connected via CAN-bus (firmware 1.16)
  • VenusGX (firmware 2.60) > currently tested with 2.62-beta5
  • Any component with latest firmware as of today


thomasw-1 asked
chriss83 edited ·

4 Answers

Fronius Zero Feed In - What happens on Network Loss?

I am considering adding some additional capacity to a setup that currently consists of an EasySolar-II.

I asked in about feeding one EasySolar into another, but it seems this is not such a great idea.

To recap what I said in that thread about the setup, currently an EasySolar in ESS mode supplies the house (blending grid power with inverter where necessary) and I do not want to feed into the grid. The idea is to add some generation capacity on one of the circuits (which goes to an outbuilding) coming from the existing EasySolar (so this setup would be on an AC-Out of the EasySolar).

The Fronius Zero Feed In system came up in that other thread, but I have looked further into how this works and have some concerns. describes using ModBus TCP to expose the Fronius control loop so that the EasySolar/Multi can control it by turning down generation on the Fronius when the power can't be absorbed by upstream loads and batteries.

The documentation also describes frequency control, but that can only be used during a grid outage (when the EasySolar can dictate the frequency of the AC waveform) and during normal operation with the grid connected to the EasySolar the only way the Fronius can be controlled is through ModBus TCP.

My concern is, what happens if the TCP link between the Fronius and the EasySolar/Multi fails. Is this a fail-safe system (meaning that if ModBus communication is lost the Fronius shuts down or regulates down to zero generation)?

I can see that this system is fail-safe from the point of view of battery state of charge, because if there's no grid to export power to, the upstream multi will vary the frequency and the Fronius will definitely receive this command on its AC lines, so can be relied upon to regulate down when there's no grid to prevent overcharging batteries.

But I'm not sure if it's fail-safe from a "no feed in to the actual grid" point of view. If the ModBus connection drops but the grid is still present, then if the Fronius kept producing excess power that the Multi didn't have battery capacity or load to dissipate, then that power would have nowhere to go except feeding in to the grid.

What happens to a Fronius configured as described in that page if the modbus TCP link is interrupted, does it shut down or regulate down, or does it keep generating power?

boristhespider asked
danielw answered ·

4 Answers

Efficiency between Multiplus and Fronius doing DC -> AC ?

I did see some of the videoes where you go trough Fronius and Victron where you discuss AC and DC coupled systems. In the video you say the Fronius is very efficient at doing PV DC to AC whereas Multi is not or that's how i understand it, why is that ?


peternielsen asked
marekp commented ·

2 Answers

Since Firmware 2.60 of the CCGx and Venus, the Button "Zero feed-in" for Fronius Inverter is not in the menue anymore. What settings do I have to make so that the Fronius inverter does not feed into the public grid?


since Firmware 2.60 of the CCGx and Venus, the Button "Zero feed-in" for Fronius Inverter is not in the menue anymore.

What settings do I have to make so that the Fronius inverter does not feed into the public grid?

Do I need a grid meter?

Are there any instructions ore manuals from victron available, for the new Firmware 2.60?

Thanks for your help


vic-sonnensspeicher asked
thomasw-1 edited ·

3 Answers

Fronius + Multiplus energymeter


Guy Stewart mentions in this webinar that you should not use Fronius Smartmeter in a ESS system but then in the diagram right after it's shown, is that a mistake ?

My house is running 3 phase system and consumption is across those 3 phases which is normal here Denmark. I was planning getting a one phases Fronius Primo 3kw and a Multiplus II 3000VA. Install the Fronius on AC IN meaning on the grid directly (not on the AC OUT) and of course a grid meter EM24 Ethernet that is recommended so both Fronius and Multi are one phase. The ESS documentation states to place the Multi on L1 but the fronius should be on what phase ? Doesn't matter ? Is there a required of a second energy meter in this setup ? In denmark most of us have new grid meters from the energy company which summs up on all phases so consuming on one phase 1kw and producing on another phase 1kw yields 0w usage e.g no penalty or cost therefore no need for 3phase inverter.



peternielsen asked
Guy Stewart (Victron Community Manager) commented ·

1 Answer

More information in VRM (Fronius)

Is there a setting in VRM that enables more information for the Fronius inverter?
I would like to monitor MPPT 1/2 voltage and perhaps more if there is option for it.

If not, is it something Victron is perhaps working on with Fronius in later updates?
Fronius has a pretty good API and the information is available in Fronius Solarweb.

Kind Regards


ehsab asked

0 Answers

3 phase Microgrid with Fronius (AC and DC coupled) Output 2

I was wondering how the Output 2 on a Quattro or Multiplus 3 phase micro-grid with Fronius works. If the Fronius is on Output 1, how do the Victron inverters make Output 2 operate? Does it operate as it normally does in a normal three phase installation without Fronius?

james asked
james-davy answered ·

1 Answer

How to get a "production/no production" signal from an off-grid system with a CCGX, Victron Quattro and Fronius Primo?

Hi guys

I have an off-grid system with a Victron Quattro, 2 fronius primo, BYD Box batteries and a CCGX.

I need to get a signal of "production/no production" from one of the components of the system so I can control my Heat Pump and disconnect it when the solar production is off.

Can you please help?


João Morais

joao-pedro-morais asked
Vangelis Beligiannis answered ·

2 Answers

3 phase 5KW fronius inverter with 3Kva multiplus 48V / 3Kva

I am trying ESS on single phase with fronius simo 5KW 3 phase inverter the fronius is connected to ACin on Multiplus (48/3000/35)

Question 1 -

A three phase fronius smart meter in connected to grid side do i need a single phase victron meter to actually display the single phase consumption on GX colour screen ?

Question 2 -

Do we need to do any software update on fronius inverter if we connecting fronius inverter to victron multiplus ACin ?

Question 2 -

Does Gx controller will display the battery status if battery does not support any communication? or does fronius portal show any battery status ?


faizan asked

0 Answers

1 Multiplus II 5000VA AC-coupled with Fronius Primo 4.0 on phase L1 on a 3-phase grid powered system

Hi guys, I am planning to use 1 Multiplus II 5000VA AC-coupled with Fronius Primo 4.0 on phase L1 on a 3-phase grid powered system. My question is: if there are some issues with 3-phase loads like a Heat Pump, when suddenly happens phase L1 grid failure and then Multiplus will work on inverter mode, although L2, L3 still powered from the grid?

pkorkas asked
marekp answered ·

3 Answers

Generators rules and solar production


I have a system that mainly uses the generator at night to recharge the batteries. The system has been configured at night rules (until about 9 a.m.) to recharge the batteries from 15% to 30%.

Many times when the sun rises, the solar power is already enough to avoid touse the generator.

Why until it reaches the 30% required by the rules, the system does not use the sun production only?

Can we bypass those rules ?

Thanks in advance

arty asked

0 Answers

Victron Multiplus II with feed-in (while grid on) and blackout operation

Hello there!

I am trying to figure out something rather simple but can't find the answer:

* The system is a three-phase system with three Multiplus II 48/5000. There is also a Fronius Symo 8.2 connected at the AC OUT of the victrons.

* Grid is connected to the AC IN (Spanish grid).

* Victrons have a 20 kWh BYD LVS battery.

We want to allow exporting all excess energy towards the utility grid, while the grid is available.

If the grid fails, we want the system to keep running, without feeding any excess to the grid, and regulating the power output of the Fronius Symo, in order no to overcharge the batteries.

What would be the recommended settings for VE Configure/ESS? Would I need anything else like an external contactor? If the Grid code was configured to Spain, will the Victrons still work in the case of grid failure?


mm-azimut360 asked

0 Answers

Fronius zero feed-in with DC Coupled solar


I would like to limit my Fronius Galvo export to zero , but have "Feed-in excess solar charger power" turned on as to only use the DC coupled solar for export, not the AC coupled.

Would this work?


Isaac Shannos asked
Guy Stewart (Victron Community Manager) commented ·

2 Answers

System overview - Multiplus II + Pylontech US2000 + Fronius Smart Meter + Fronius Inverter Symo + Raspberry (venus os)+ excess feeding

hi all,

I´m planning to install an ESS with the components listed above.

Has anybody realized this configuration already and may support me or has an overview/schematic?


hansbaer asked

0 Answers

Alternative to frequency shifting for adjusting AC PV power?

Hello, questions- is their a victron version of Selectronics managed AC coupling instead of the current frequency shifting as this is more precise and would eliminate any clock timer issues as well..

If not something for the Victron team to look at implementing perhaps?


drae asked
Guy Stewart (Victron Community Manager) commented ·

1 Answer

ESS: Basic Understanding for Factor 1.0 rule and 3 Phase PV Inverter


I couldn't find the answer to my question in the forum, so I'd like to ask it here:

I'm talking about an ESS Scenario where I can use Phase 1 as a Backup if the grid fails. (One Multiplus-II between Grid and Phase-1 Loads).

I have a Fronius Symo 5.0 and a Multiplus-II 3000. So I'd like to install 1 phase of my fronius PV on AC-OUT just in case the Grid fails. But as far as I have understood I cannot do that because the PV Inverter delivers 5KW and the Multiplus-II can only handle 3 KW.

But what I do not understand is the following: How does the PV Inverter split the energy delivered from the PV Modules on the 3 phases? And what's the maximum load that's deliverd on one phase? Let's say phase 1 is on AC OUT of the Multi, phase 2 and 3 are on AC In side. So in case of a grid failure: would the PV Inverter put the entire power on phase 1?

So let's say I add a 2nd Multiplus-II. Then Factor 1.0 rule would be OK. Phase 1 and 2 of the PV Inverter would be on AC OUT, Phase 3 on AC IN side. How would the power be deliverd from the PV Inverter in case of a grid failure? Would it deliver all power on Phase 1 and 2?



florianro asked
Rob Duthie edited ·

3 Answers

ESS why datamanager fronius by excess power


Sorry for my english,i'm french.

I installer to:

- multiplus II 48/5000 with a genus GX

- Mppt 150/45

- lifepo4 400ah battery

- Fronius primo 5.0-1 I

would not do any network injections.

The PV inverter will be connected to the AC output. mppt directly on the batteries.

I would like to use the ESS zero injection function.

For my self-consumption to be optimal I would like to use the smart counter fronius at the level of the AC output of the victron to be able to use the solarweb to activate the inputs of the datamanager box on the are connected the relays and the pilot from the 'information "by excess power".

And so that the rest of the surplus is injected into the battery, before zero injection works.

So would it be possible to install the smart meter at the AC outlet of the victron without interfering with the ESS system?

Thank you nicolas

minico13580 asked

0 Answers

2 x Fronius Symo -> Zero Feedin not working on one Symo

Hi Forum !

i have expanded my system with a second Fronius Symo. I used zero feedin for over a year successfull with the first symo. Both Datamanagers have absolutely the same settings but the second symo is not working with zero feed in. So at the moment one (the old) inverter is doing his zero feedin job nicely .... the other is feedin in if my batteries are full and the first inverter ramped down to zero.

The only difference i can see is, that the connection type of the working inverter is "sunspec" and the not working inverter is "solarapi". Did i miss something where i can change this ? I can not find anything regarding inverter connection type in the venus settings or the datamanager settings. Also maybe the connection type has nothing to do with my problem.

I hope someone can help me out ....

Thanks a lot !


stxshadow asked
stxshadow commented ·

3 Answers

Fronius off-grid setup Hello, my current full off-grid system consisting of: * two 150/70 MPPT charge controllers, * CCGX, * Multiplus II 48/5000, * Pylontech Batteries 13.8 kWh, * supplied by 4560watts of solar.... I have another 12 x 405watt Canadian solar Panels to utilise. I would like to use a fronius 4.0.1 in an AC coupled setup to compliment my currently DC coupled system.... Will this be a feasible setup? Any suggestions appreciated.. Cheers....

drae asked
drae commented ·

1 Answer

ESS, Fronius zero feed in and grid setpoint negative setpoint without draining batteries?

Hi I have an ESS system where ive incorporated a fronius primo 8.2kW inverter i have all communication set up and working for zero feed in, however i want to allow export of 16 amps or 3.68kW as this is acceptable, I assumed i would be able to set the gridpoint to -3600 and it would allow the inverter to put upto this amount out onto the grid before limiting output. However the victron actually started pulling power from the batteries to export 3600 watts to the grid. Is there a way around this as the customer can actually gain a tarriff from exported units but it makes no sense to drain the batteries into the grid.

Thanks Jack

jacko asked
dayandnight commented ·

2 Answers

Unknown battery draw down


My recently installed system has a colour control which reports (contradictory) ve.bus battery state information from the Mutli's and a 3ph PV inverter in off grid configuration. With All output MCCB switched off, there is a constant +-100W (2A) draw indicated in the battery symbol in addition to the L1-L3 standby load. This discrepency is also not included in VRM portal output.

Going into winter this unplanned loss will significantly affect the battery SoC. Is this indeed an undocumented standby consumption within 3ph configuration of the Victron inverters, or is the in built BMV reporting incorrect info?

SoC at dawn reads: <60%

Lead acid capacity:9.8Kwh

Reported night time load: 2Kwh



rnieckau asked
Daniël Boekel (Victron Energy Staff) commented ·

3 Answers

Fronius and Color Control

Is it possible to communicate a Fronius inverter with a Victron Control Color without having internet?. The Installation is a Rural Sector

carlos-farfal asked
Riaan Barkhuizen answered ·

1 Answer

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