Fronius Image


Why is the Multiplus II frequency changing before the battery is full?

Good morning, I have a fronius connected to accept out 1 on victron multiplus II, I am checking how it runs without public grid, but I realize I have solar power, but the victron increases the frequency an the battery is not full. What could be the reason? Thanks in advance



palom170 asked
palom170 answered ·

2 Answers

AC LOADS readings jumping up and down like CRAZY on Fronius AC coupled when frequency above 50.2V

My system is off-grid and has a Quattro 48/8000 with a FRONIUS PRIMO 3.0 on AC out, an MPPT 150/70 and a CCGX .

When battery is in float (55V) and the Fronius (on AC OUT) is regulated be the frequency (above 50.2Hz) the AC loads readings on the CCGX go crazy! Up and down by hundreds and even thousand Watts.

As soon as the frequency drops to 50 all is back to normal.

Any ideas?

Vangelis Beligiannis asked
Vangelis Beligiannis commented ·

2 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
thomasw-1 answered ·

5 Answers

Does frequency shift regulation depend on the nominal inverter power?


if a Primo generates 3kW at 50Hz and the regulation goes to 51,9Hz, what's the new power rate?
Is it 50% of 3kW or is it 50% of the nominal inverter power?

Or asked differently: is the regulation of an inverter with less nominal power more accurate than with a bigger unit even if there is the same solar power installed?

As this is a little bit specific probably @Guy Stewart (Victron Community Manager) can answer?

Thank you!



porcini asked
porcini commented ·

1 Answer

ESS with grid parallel PV Inverter

Dear community, good morning

I have a Multiplus II GX Inverter charger configured with ESS asistant under Optimized mode.

Battery bank 48V 4 x 12V LipoFe Smart Batteries from Victron with VE.BUS-BMS.

The installation has an ET112 grid meter monitoring both Multi and load power.

Grid Set Point is set to 50W to avoid feed in the grid.

Currently I have set Schedule Charging to:

Schedule 1: Everyday Starts at 0:00 / Duration 7:00hs

Schedule 2: Everyday Starts at 7:00 / Duration 11:00hs Stop on SoC 50%

This will charge the batteries during off peak tariff from 0:00 to 7:00 am, Prevent any discharge from 11:00hs to 18:00hs and use all accumulated power during the night.

I am adding a Fronius Primo grid tie inverter with (Fronius Zero feed will be enabled).

I will change my Schedule 1 and add Stop on SoC 70% so I can take advantage of the grid tie inverter to charge the batteries.

My question is how will the system behave since from 11:00hs to 18:00hs Schedule 2 two will be running?. Will it override charge from the grid from Shcedule 2 and charge from the excess in PV Inverter?. I want to take advantage of the solar excess but prevent from charging from the grid during that time.

Thanks for your support.

Best regards,

Javier Moran asked
Javier Moran answered ·

2 Answers

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

Baud rate conflict 250/500kbit/s - Parallel Quattros-Cerbo-Pylontech-250/100MPPTs-Lynx....

Off-Grid system has 2 x Quattro 48/10000 in Parallel with 24 x Pylontech US2000 & LV HUB, Cerbo GX, Lynx Distribution system inc Lynx Shunt, 2 x 250/100 VE.Can MPPTs ground array, 2 x Fronius 6KW PV Inverters roof array. Perking 12kVA Generator. All kit a few months old. All Firmware updated to the very latest.

Following the Victron documentation Pylontech (Type B cable) to Cerbo VE.Can BMS connections. MPPTs and Lynx Shunt to Cerbo VE.Can connections. Quattros to VE.Bus connections. DVCC enabled, settings as per the book.

Problem: With CAN-bus BMS (500 kbit/s) CAN-profile in the CCGX as per the book, the MPPTs and Lynx Shunt disappear. They reappear if the baud rate is set to 250 kbit/s. Various problems manifesting such as auto-run generator stops working etc.

Am aware that others have had similar issues with the 250/500 kbit/s conflict. Any suggestions how to get round this - thinking switch the MPPTs to VE.Direct connection instead of Can but hate work-arounds and want the correct solution!

Thanks in advance!

colins asked
colins commented ·

1 Answer

New fronius Gen24 product support

Does anyone know if victron are supporting the new Symo/Primo Gen24 models?

Anybody know if they are detected and read by the VenusOS?

alan asked
alan answered ·

1 Answer

Fronius Victron connection


I am in the process of designing an off-grid solar household system. I would rather start small with good modular components than go big and cheap. I am currently looking at a Fronius Primo 8.2 running of 30 x 360W Canadian Solar panels at 48V. This will then be connected to either a 5Kw Quattro or 5kw Multiplus (advise on this choice will also be appreciated) to charge 2 x 9,6Kwh Pylontech battery banks (19,2Kwh at 48V). I am looking for wiring diagrams for such a system and advise on any peripherals that will be needed. Can I connect the 8.2 Fronius to the 5kw Victron? Where will my PV power be delivered? If I generate 8.3kw through the Fronius and dump everything into the 5kw Victron will I loose the extra 3.3Kw? Could this be remedied by using the double AC in options on the Quattro? There seems to be limited information on this type of paring on the net and any advise or guidance will be greatly appreciated.


archman asked
Matthias Lange - DE answered ·

1 Answer

ESS with Fronius and zero feedin is overcharging Pylontech Batteries


I have a systems that is set to Zero feed in.

It is made up of a Multiplus-II 5kVA , Fronius Primo 5.0-1, MPPT-100 and 12kW Pylontech battery.

The Fronius is connected to Out-1 of MultiPlus.

The problem is that when the battery is 100% charged I start getting battery over voltage errors. 53.8V-54V and the Pylontech switches off when 54V is reached.

This started to happen after replacing one of the MPPT-100 with the Fronius.

The battery charge voltages are set correctly on the MultiPlus.

What else should I look at.


Hugo Russouw asked
Hugo Russouw answered ·

5 Answers

Fronius L1/L2 assignments

2 Quattro in 120/240 (first L1+N, second L2+N)

2 Fronius 120/240 in parallel (each has L1, L2, and N)

CCGX sees the Quattro as one system

CCGX sees the two Fronius as separate inverters


In the "PV Inverters" config I have to assign the PV inverters to a phase:


But of course this makes no sense, because both Fronius inverters operate across both phases.

I feel like this is throwing off the zero feed-in and phase compensation features, as well as the reporting.

If I go into one of the inverters to look at the power:


1575W is the total power that inverter is making on both phases. ESS is counting it all towards phase 2.

vincent asked
Daniël Boekel (Victron Energy Staff) commented ·

6 Answers

Fronius on ESS without MG50?

Hi there,

since Fronius Support is taking some time to answer the question, I might as well post it here.

The local utilities require a specific cosPhi setting in the inverter, which - for my knowledge - requires a countrysetup other than MG50.

How does changing from MG50 to i.e. DE2U affect the behaviour of the inverter in an ESS?

Feed-in only needs to be limited to 70%, so no zero feed-in required.

As always, thanks for the help!


chriss83 asked
alan edited ·

2 Answers

VRM dashboard not showing PV inverter history and odd placement


First off some details of the system:

GX Device is a Cerbo (FW v2.60)

3 phase Multi II 48/5K on ESS

PV Inverter Fronius Symo 10.0-3 (FW 3.16.7-1) on ac-out

no seperate energy meter on ac-in side

I was wondering why there is no history of the PV Inverter yield on the VRM dashboard and why it is not shown on the ac-load side, but on the top, which seems odd. PV inverter is correctly shown on the console and is working as intended.

Advanced view of course is showing the full history of the solar yield.







chriss83 asked
seb71 answered ·

2 Answers

ESS using Multiplus II and Fronius, 1-1 rule


I currently have a Fronius primo 5kw inverter with 4kw of solar (2 arrays NW and NE) and am looking to add a victron Multiplus-II GX to provide some storage and redundancy for power outages.

I understand that with 4kw of solar and the inverter being only 3kw I will run into trouble with a grid outage if I have the solar inverter on the output of the multiplus due to the 1-1 rule.

Im wondering if there is any way to reduce the fronius down to 3kw as soon as the grid fails to make this work?

I guess any system would need to be very fast to avoid any inverter shutdown however if the solar inverter was to shut down for a short time then ramp back up slowly to a reduced output this might work?

Any thoughts are very much appreciated.



nzmikec asked
sathr answered ·

3 Answers

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

Zero feed in not working

Have installed a ESS system with a fronius primo 8.2.1 on the ac-out of a victron quatro 8000 and have disabled feed in as the grid does not permit it. some sunny days when batteries are charged and not much load the house it will export to the grid although the as the photos show fronius zero feed in is active, but when i check vrm and error message shows on PV status but when i check fronius solar web no fault is active.





dubzy777 asked
michael-yasay edited ·

2 Answers

Fronius PV Inverter is missing in Dashboard after changing connection from LAN to WiFi

Hi, I had to change the Fronius Primo Inverter connection from LAN to WIFI connection ( AC In on Multi). After changing the connection, the inverter disappeared from the Dashboard and from Device List. In Remote console and in Avdvaced is still visibne and functional. I tried to restart everything, change IP addresses, deleted from the device list, but without success. Please advise how to get the inverter back into the DashBoard. Thank You.

Remote console and Advanced- everything is fine:



Dashborad nad Device list – PV Inverter in ACin missing


ondra asked
Paul B answered ·

1 Answer

Can the PV inverter support assistant be configured to start ramping down at 57.6v instead of 54v?

At the moment the absdorption saying is 57.6v for absorption but the PV inverter support assistant ramps down Fronius when the batteries are at 54v so it takes far too long to charge the batteries under solar. When the generator is on, it will charge at 180amps until 57.6v then go into absorption then float as it's supposed to but when it's under solar it will charge at 180amps to 54v then ramp down considerably so even though the charger wants the power the PV inverter assistant won't allow it. Can the setings be changed in the PV inverter support assistant to chasnge it from 54v to 57.6 as per the charger setting?

daren-connor asked
Paul B commented ·

1 Answer

Issue with MultiPlus 48/5000/70-100 connected with Fronius Symo 8.2-3-M

I just installed the multiplus on the ACin of 1 phase of the fronius symo with pylontech batteries for backup and solar energy storage.

I.m not allowed yet to feed excess energy In the grid so fronius is set not to feed excess energy In the grid. A fronius smart meter needing installed.

The fronius and multi are connected via venusGX

1. 1st issue is that when I lower the SOC of the batteries the fronius is being throttled down and power is being supplied only from the batteries.

2. 2nd issue with charging the batteries. The fronius will not ramp up to provide additional power for the charging.

Any ideas why this is happening?

mihaimicu asked
mihaimicu commented ·

1 Answer

The system is locked to 53 Hz and does not resume

Hi, I have followed all your guidelines and the Firmware version 476 is at the latest revision but the Quattro still holds our the ac coupled Fronius even when the BYD battery is below 54V

cleverconnections asked
Paul B edited ·

1 Answer

What is the reasoning mixing panels West and East on same MPPT ?


I have two sided of roof, one pointing almost West, one almost East, (20 degree turned towards east) (location is Denmark) see picture here :



My plan was : 3,7Kw array on West and 2,8Kw on east, my reasoning was that we consume more energy towards the end of the day than in the morning. I am planning doing a DC and AC coupled system using Multiplus II, Fronius and a Victron MPPT.

My plan was to have one side on the Fronius and one side on the MPPT but somebody suggested to different.

He suggested take half East to Fronius MPPT1, half West to Fronius MPPT2 and the rest from West and East in parallel to the Victron MPPT. He said it's better to do this because the MP2 can only charge with 1.5kw on the battery from AC (if there is surplus from Fronius).

Why is that a good idea ?

Here is a full diagram


peternielsen asked
peternielsen commented ·

4 Answers

CCGX Not showing PV Production

We have a customer with the following installed:
1 x Victron MultiPlus II (48/3000/35-50-230V)

2 x Fronius 3kW Primos (1 on the input, one on the output)

7kWh of BYD batteries

Currently everything is working ok, except there is no pv production being recorded and displayed by any of the Victron devices.

Using the Remote Console I can see that the MultiPlus is aware of both of the inverters. The customer has a Solar.Web monitoring setup for the Fronius inverters, but can only monitor one of them, so the customer can't use Solar.Web to record production data.

All of the devices are connected to the customers wi-fi, though it is not the best signal strength at the inverters.

The customer used to have the PV Production showing on the CCGX, and in the past a reboot through the CCGX would get it to find the Fronius', though this isn't working anymore.

I have had the customer run through a full shutdown of the system and restart, but this hasn't changed anything either.

There hasn't been a firmware update installed since the customer had the ability to measure

Any help would be greatly appreciated.

sd-jesse asked
sd-jesse commented ·

0 Answers

[SOLVED] Generator woes in 3p hybrid AC (Fronius)/DC system


Problem1: Generator feed-back

Cause: Gridcode (Germany) & LOM type B enabled for AC-IN1 (where the Generator is connected. Symptom was that there never really was any demand on L1.

Solution: Disable LOM on AC-IN1

Problem2: Generator was not demanded beyond 4A per Phase, although AC Input current limit was set to 7.5A

Cause: Unknown, probably firmware bug in either Quattro 469 Firmware or the 2.60 Venus Firmware

Solution: Wait 3 hours, turn Generator on again, then it respects the AC Input current limit again

Problem3: Dynamic current limiter does not work (description see below)

Cause: Gridcode enabled

Solution: Disable gridcode, thanks to @Daniël Boekel (Victron Energy Staff)

I would have expected a Gridcode to apply only for the AC-In defined as "Grid" and not for the one defined as "Generator" (and I still do), but as the genset functionality is more important for our off-grid installations, disabling gridcode altogether is an acceptable trade-off.

So the question is why. I would have expected the Quattros to pull the defined amps from the genset symmetrically on each phase and to juggle real-world consumption (or excess) on AC-Out.

Instead, I see a constantly skewed L1 with feedback to the genset - see picture.


Evidently the Fronius (Symo 6) has something to do with it, because when that thing is turned off, the feedback is gone. So I wonder what's wrong there or if it falls into the "It's not a bug, it's a feature" category.

Moreover, the generator runs less-than-smooth. All load changes seem to go directly to the genset, instead of being compensated by the Quattros (power assist or whatever), so the genset Amps go up and down like a kangaroo.

I would assume that defining an AC-IN source as "generator" means that "feed-in" is an absolute no go for the quattros. So why isn't it?

petajoule asked
petajoule edited ·

5 Answers

Grid inline topology: What happens when the grid fails?

Hi Community,

just another question regarding ESS. My Setup is 3 phase grid inline topology. ESS is not allowed in an island setup as far as i know. What happens to my setup if my grid fails ? Will ESS take care of the fronius inverters ? Will it supply power to the house ? I can not find an informations regarding this in the documentation.

Thanks a lot !


stxshadow asked
Guy Stewart (Victron Community Manager) commented ·

2 Answers

PV throttling very often

I have recently installed an ESS System (Victron Multiplus 48/5000/70) with one BYD 5kWh and Fronius PV Inverter connected on AC out (on-grid system).

ESS is on "Optimized (Without BatteryLife)". The connection between PV Inverter and Victron is wireless.

The system is working ok but I have some issues which for the moment are unsolved.

For example, the PV production is frequently stopped just to return in the next seconds.



As you can see from the graph, PV is having a strange behaviour when charging the batteries, the graph looks like a saw teeth when I was thinking to be like a smooth line. The PV throttles down to 0 frequently as you can see and I do not know the cause of this.

Any ideas?

ccb asked
ccb edited ·

3 Answers

Frequency Shifting and Generator

For off grid sites with a generator and AC coupled solar.

Is there a chance that when the Gen comes on (for load support etc), and if the battery if full, that the AC coupled solar (ramped down) , then , the frequency shifting is overridden by the Gen set (if genset provides 50Hz). Is there a chance energy could back-feed and damage genset?

Guess this could happen if the genset is small and the Fronius is large?

If yes to above, is there recommended ways to avoid this in the manual? I've watched the fantastic webinar in the AC coupling (Fronius & Victron webinar) but nothing was mentioned.

We have a work around, but would prefer to use one provided by the manufacturers.

Look forward to your feedback


David asked
Daniël Boekel (Victron Energy Staff) answered ·

2 Answers

Fronius Zero feed kann nicht aktiviert werden / Fronius Zero feed in can't be activated


Nun hab ich es geschafft, das ESS System in VE-Config zu konfugurieren und im CCGX zu aktivieren.

Folgende Komponenten sind im System:
Victron EM24 RS485
Victron Color Control GX
1x Victron Multiplus II 48/3000-32
Fronius Symo 17.5-3-M
4x Pylontech US2000

Nun habe ich aber das Problem, dass ich Fronius Zero Feed-in im CCGX nicht aktivieren kann, da es dort nicht steht.

Am Fronius ist Modbus mit tcp und Sunspec int+SF ist aktiviert.

Wenn ich den VE-Bus vom CCGX abstecke und Einstellung mit MK3USB am Multi vornehme fährt der Fronius komplett mit der Einspeisung runter (Throttled), also irgendwas scheint ja zu kommunizieren.

Fehlt hier noch irgendeine Einstellung ?


I set up the ESS System with VEConfig and started the CCGX.

Components of the System:
Victron EM24 RS485
Victron Color Control GX
1x Victron Multiplus II 48/3000-32
Fronius Symo 17.5-3-M
4x Pylontech US2000

Now I have following problem, that the Fronius Zero feed in cant be activated in the CCGX because I can find it there.

Fronius is connected by Modbus and the settings are done (Modbus tcp and sunspec int+SF)

If I disconnect the VE-Bus from CCGX the fronius is throtteling to ca. 50W.







Wäre super, wenn mir hier jemand helfen könnte! :-)




stephan-wittmann asked
jfleissner commented ·

2 Answers

Is Off-Grid AC Coupling any good with Fronius or Solar Edge?


From what I can tell Frequency shifting isn't a perfect solution for an off grid ac coupled solar control.

Does Victron support both Solar Edge and Fronius AC coupling options 100%? Are there any limitations to frequency shift control? Other than the 1:1 rule.

Is Selectronic Frequency shifting (generic AC coupling) more advanced than Victron? I heard Victron was 25% steps up or down in power.

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

1 Answer

Simultaneous MPPT and Fronius doesn't use all the PV to charge the batteries


Here is the configuration of Quattro 48/8000:

Fronius Inverter (7kW) on OUT1

MPPT (4kW) through DC-BOX on Pylontech Lithium batt

it runs under ESS Optimized (without BatteryLife).

I don't understand why the Fronius energy doesn't go to charge the battery ... here the problem :


1570W into the grid instead of charging battery...

how can we correct this behaviour ?

I can give you more details if necessary.

Best regards,


khaem asked
khaem commented ·

3 Answers


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