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AC PV Coupling

MultiPlus-II with AC-Coupled Inverter and Cerbo-GX not showing negative load on AC output for AC PV Inverter

I have a MultiPlus-II 5kVA running in an offgrid system with all Loads connected to AC Out 1
The batteries (Pylontech) are mainly charged by a victron Mppt, but in addition I have an AC-Coupled PV Inverter (Solax X1-Mini) connected to AC-Out2.

In the MultiPlus-II I have an assistant installed which switchs AC-Out2 on and off by the current state of charge, because the very simple inverter has no options to reduce power output (e.g. by changing the grid frequency).

Later I've installed a Cerbo gx and enabled DVCC, from that moment on, the MultiPlus-II didn't light up the Charging LED's anymore and on the Cerbo GX I only see 0W power consumption on the AC side, when the MultiPlus-II is charging the batteries.

With ve.configure or with the Grafana-Dashboard soultion instead I can see e negative value for the AC-Out power.

Is there an option to show up these negative values on the cerbo-gx as well?

robtor asked
shaneyake commented ·

2 Answers

AC coupled 1:1 question


If the AC PV export counter is in such a place, and total AC PV limit set to equal the 1:1 rule would such a setup be in theory possible?

Tom h asked
shaneyake answered ·

2 Answers

Cumul des puissances Fronius + Multiplus en couplage AC


Je dimensionne une installation Hors-Réseau avec un Multiplus + couplage AC Fronius Primo + couplage DC.

J'ai bien compris la règle 1:1 en couplage AC.

Mais je cherche à savoir si sur une belle journée et avec les batteries chargées on peut cumuler ou dépasser la puissance du convertisseur + celle de l'onduleur. P_tot=P_Multiplus + P_Fronius

Le client souhaite alimenter une machine de 2000W uniquement lors des belles journée mais avec ces autres équipements il peut y avoir des consommation jusqu'à 4200W au total sur 2h cumulées.

Je pense coupler en AC un Multiplus 3kVA avec un Fronius Primo 3kVA et commencer avec 1.5kWc en couplage DC que je peux facilement faire évoluer.

Le but est de na pas passer sur 5kVA car le client ne consomme pas plus de 2000W 70% du temps

Merci de votre lectures et vos réponses

tdy74 asked
Thierry Cortassa (Victron Energy Staff) answered ·

2 Answers

MyPV AC-Thor in off-grid system - settings?


the manual ( ) says that when using AC-Thor in an off-grid system frequency shifting (PV-inverter assistent) has to be activated at the Multi.

- Is this also necessary if only DC-coupled PV is used (no PV-inverter on AC-out)?

- what are the frequency settings in the "PV-inverter" assistent? Are the default-settings ok?

Best regards

e-box asked
Robert Bazalgette answered ·

5 Answers

Is it allowed to connect a microgrid inverter to acout1 while using th Multiplus ii 3000 in Hub 1 mode?

I am running two pv systems in my House. Since 2011 a Grid tied inverter sma 2kwp. Since this year i also have the multiplus ii 3000 with 4kwp mppt 150/35 loading the pylontech batteries. The new system uses hub 1 mode which means tue multiplus only switches to the grid when the batteries are low or the load exceeds the power capabilities of the multiplus.

I would like to add mir pv power on the acout1. Anyone knows a solution for this?

harry59 asked
harry59 commented ·

0 Answers

Multiplus II PV-Strom am Ausgang 1 messen

Ich habe am Ausgang des Multiplus II maximal 2400W PV (3x 800W Micro-Wechselrichter Hoymiles) angeschlossen und würde diese gerne als PV Strom im ESS anzeigen lassen.

a) der Multiplus zeigt am Ausgang (Critical Loads) 0W an wenn die Wechselrichter einspeisen. Wenn ich statt den WR einen Verbraucher anschließe wird der korrekte Verbrauch angezeigt. Kann der Multiplus keine "negativen" Leistungen am Ausgang messen? Oder kann man das einstelen?

b) kann ich alternativ einen ET112 vor die Wechselrichter schalten und den dann so einstellen dass die gemessene Leistung als PV-Ertrag am Ausgang angezeigt wird? Die Rolle der erkannten Energy Meter lässt sich ja als PV Wechselrichter konfigurieren und dann kann man auch die Posttion am Ausgang einstellen Hat das jemand so laufen?.

behl asked
behl answered ·

2 Answers

Can I use multiple em24 energy meters?


is it possible to use a couple of energy meters at the same time, i would like to have 1 for grid in/out and i would also have to have 6 for PV's which are connected to AC OUT on Victron Quattro.

paulmarinas asked
Matthias Lange - DE commented ·

3 Answers

SMA Sunnyboy comms with Multiplus

I have an SMA Sunny Boy 5000TL that has been running with an Multiplus 5kw for 5 years now but we recently installed an Lithium bank as well as more panels but connected them on a separate Victron MPPT, but now the Sunny Boy has a lot of excess capacity and is pushing back into the grid. There is no Comms installed between the Multiplus and the Sunny boy only an Victron current sensor was installed and on the CCX it only shows PV invertor, is there a way in have the two units talk to each other? to try and limit the grid feedback. The Sunny Boy does have an network module installed, Any help would be appreciated.

bart182 asked
Alexandra edited ·

0 Answers

ac coupling fronius 5kw ac input connected and 5kw ac output connected

hi guys

my actual system is a simple grid-tied single phase 5kw fronius primo with 7kw of panels. im in the process of adding another 5kw fronius primo, a multiplus ii 48v/5000/50-70 and 200ah battery bank. i would connect one fronius to the multiplus in the ac input and the second fronius to ac output of the multiplus. the multi will be connected to the main panel and the battery bank.

will this setup work?

will i keep feeding the grid all the excess energy?

is the rule 1:1 met as the fronius on the ac output is 5kw?

Will 4mm2 wire be ok or i need bigger wires (the distance beetween inverter and grid is about 4mt)


fabrizio-baglio asked
tekidan answered ·

1 Answer

Kostal compatibility

When will it be posible to integrate Kostal Plenticore with BYD Batterie and EM to the Colore Control (Venus)

maremotomoto asked

0 Answers

Fronius error state 105 ac-coupled system with victron

Good day

I have recently installed a Fronius primo-6 together with a quattro 48/10 000 in an ac-coupled installation

the system works perfectly when the main switch on the DB board is off (thus making the system completely off grid) but when the Main switch is switched on the fronius gives me an error state 105 when reading up about this it means the ac grid frequency is to high... i tested the frequency from the grid and it jumps around 51Hz to 52Hz which should be will within the fronius parameters so my question is has anyone experienced something similar are there settings that are not correct on the fronius any help would be appreciated


hannu asked
rafa answered ·

2 Answers

AC Coupled inverter on AC-OUT with export limiting to the INVERTER!

I am busy with an off-grid installation that has a Goodwe GW15KN-DT PV inverter on AC-Out of a set of Quattros. The PV Inverter assistant is configured and frequency shifting works as expected as the battery approaches full. The Goodwe is supposed to be VDE4105 compliant and the suppliers assured me before purchase that it was able to reduce power in response to frequency shifts. In practice the Goodwe does not respond appropriately to the increases in frequency. It does cut-off once the threshold for frequency error is crossed. But it does not throttle back for lower frequency increases.

A long period of troubleshooting with the suppliers and including Goodwe HQ has not produced results beyond establishing there is a problem and that a firmware fix is somewhere in the pipeline. They are not able to provide any information on when this may be.

In the meantime the Goodwe and it's array sit idle!

Would it be possible to implement the export limiting function in the Goodwe such that it will not export back in to AC-Out on the Quattros and only follow the loads on the distribution side? i.e. the CT clamp is positioned between the PV Inverter and the Quattros.

I understand that if this is not 'a very bad idea' for technical reasons then the Goodwe would not contribute to battery charging. This would be acceptable at least until a more robust solution is devised by Goodwe.


rodgerd asked
Petr P commented ·

0 Answers

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
holumiedey edited ·

2 Answers

generator erattic charging with quattro fronius AC coupled off grid

Hi, i'm wondering if anyone can help with my generator to quattro charging issue. I have an AC coupled off grid system with 2 x fronius primo 8.2 ( each carrying 8700w of PV ) feeding into a Victron Quattro 15000va inverter and a 27kwh Kokam lithium battery.

The generator is a 25kva which is all hooked up to auto start. At first it worked fine but recently when it starts the quattro is drawing the power very erratically and the charge current from the quattro is all over the place but at a much lower rate than its capable of. Sometimes the generator will level out as normal if I start a big load such the mig welder or the toaster and kettle together would do the trick and other times nothing works.

Also sometimes during the day the fronius's will shut down several times and if we are drawing more than the Victron can handle it will shut down due to overload as the fronius aren't helping anymore and needs to be restarted.

If anyone can help it would be much appreciated.

Thanks lee

lee-odonohue asked
basil katakuzinos answered ·

1 Answer

AC Coupled Solar issues

Good Morning,

My question is around AC coupled solar. We currently have 3x PV inverters and 1x Quattro 48/10000 and 2x DC MPPT's (Victron 100/20, Victron 150/45)

our first inverter (Solax 5kw) is on AC input 1. the other 2 (Fronius Galvo-3.0.1) are on AC output 1.

our quattro is not set to back feed the grid its excess power.

We see constant issues when the battery goes to absorb. when i have zero feed in enabled the two Fronius galvo constantly stop producing (they appear to reset). I believe its because the solax inverter is feeding the grid its excess. therefore the fronius are told to reduce there output. am i right in this assumption ?

We only have 35kw of batteries and we can only charge at a max of 140a but we normally limit it to 110A. what i would like to do is tell the victron to prioritize charging from the fronius and only use the solax as a last resort. Also is it possible to exceed the factor 1.0 rule if you use the AC Out 2 for additional solar ?

lmnewey84 asked
gherlt answered ·

1 Answer

Fronius Solar inverter AC Coupled with Victron

Sorry for the newbie question. I would like to add energy storage to my Fronius solar system. I wanted to gain more knowledge so that I know what to ask for / expect.

I read the AC coupling documents but I'm a little confused about where the Victron fits into my system.

Can the Victron simply be installed on the same solar supply circuit and in parallel with the Fronius inverter, connected to AC-out? Nothing connected to AC-in / AC-out2?

Can I assume Fronius will continue to export to the grid if

  1. Batteries are full
  2. PV output capacity exceeds battery charge capacity. (or does the battery need to be sized accordingly?)

There is no need for a CT clamp or energy meter before the main breaker?


steven-hingley asked
steven-hingley edited ·

2 Answers

AC Coupled Fronius Drops Power on Shifted Frequency Prematurely and More than Needed

Hi, I have an AC-coupled Fronius Symos on 3-phase configured Quattro inverters. I have enabled Frequency shifting in ESS assistant with pre-set configuration: starts at 51, lowest at 52.7, shuts down on 53Hz. I have set the Fronius on MG50 to enable this power reduction on shifted frequency. But lately I noticed that at 80% SOC, the frequency starts shifting up, and the batteries cannot be charged properly on AC PV power, although enough power to charge them fully is available. I also know that Fronius on MG50 starts power decrease at 51Hz and shuts down on 52Hz. What can I do to have better charging for my batteries on AC PV (start frequency shifting on 90% SOC and end with 53Hz on 100% SOC)?

Nazareth Kevorkian asked
Nazareth Kevorkian commented ·

2 Answers

3 phase AC coupling Fronius 10kw + Victron

Hi, i want to install 10kw PV system AC coupled Fronius Symo 10.3 with Victron inverter/charger.

3 phase system, i will add batteries later.

Its not clear to me which Victron inverter/charger connects best to this Fronius for 10kw 3 phase .

If somebody can help me with the design i would appreciate it .


aurelian-munteanu asked
shaneyake commented ·

1 Answer

Can I go from AC coupled PV to not AC coupled PV and back with the switch?

At the moment my on-grid inverter is connected in front of Victron system.

This on-grid inverter is not on the list of inverters recognized by Victron and does not react to frequency shifting used by Victron.

I would like to be able to move this inverter from not AC coupled to AC coupled and back with the switch.

Can it be done?

The reason for it is that, when inverter is AC coupled and Victron fails, I can use a bypass switch to bring power my loads. When it happens my PV inverter is also disconnected from my loads.

In this situation I would like to "move" my PV inverter to AC input side and be able to use its production when grid is present.

The other reason has to do with my grid operator.

They are preparing to force the owners of PV systems, connected to the grid, to turn the PV system off on their request, or even do it automatically by the signal from the grid.

In that situation I want to have an option to go off-grid rather that turn my PV off.

marekp asked
marekp edited ·

1 Answer

Microgrid AC loads in VRM/color controll

I have a microgrid solution with Quattro and fronius without grid
Also a Can-MPPT directly on battery thrue a BMV.
System works very well.

However it would be great to be able to see real AC loads in color controll and especially in VRM advanced to get a trend of it .
Now you have to add PV inverter power (fronius) and AC loads (Quattro) and subrtract battery charging power minus MPPT charge power.

txs Marcus

maka asked
shaneyake commented ·

2 Answers

AC Coupling with Fronius IG Plus A 11.4-3 Delta

Hello all,

I live in the US and am asking this question for my father who has the stated inverter and would like to add AC coupling to his grid-tied system so that it will work when the grid power is disconnected.

Is this possible with this unit?

Any idea what hardware would be best to add to make this work?

I have read this post:

and understand that this inverter may not have the appropriate software installed - is there any way to confirm that? (I'm assuming I need to contact the manufacture directly, but I'll ask anyhow)

joe-f asked
joe-f answered ·

1 Answer

3+3kW AC coupled system design


We are designing 3+3 kW system. Because of financial constriction and pressing need to upgrade the current system we are planning to build our new system in two phases.

First phase would be 1 x Victron Multiplus II 48/3000, 1 x Fronius Primo 3.0-1 with around 4kW of PV, 320Ah 48V traction battery system (24 * 2V batterys) and Cerbo GX for system monitoring.

The second phase should be implemented next year. We would then add another Victron Multiplus II 48/3000 in parallel with the first one and another Fronius Primo 3.0-1 with around 4kW of PV.

This is a offgrid system, most of the power usage is during the day.

There is a 2kW generator for backup.

In addition to that we would probably add a micro water turbine (PowerSpout), also AC Coupled trough Ginlong Solis Mini string inverter. We could get from 500 to 1000W form the PowerSpout. I know that this takes the system over the 1:1 rule. But water turbine would be used when there is no PV power (bad weather or night).

I don't have the exact question, just need the sanity check for this long term plan.

Thank you!

mterman asked
shaneyake commented ·

0 Answers

Solar yield reads 0

I've got an EasySolar 1600/24. I've wired it up to my battery bank, and I've got 500W of panels (300W in series and 200W in series so I'm below 100V).

The VRM dashboard says my PV Yield is 0, but it's a sunny day and my battery voltage is declining only very slowly (and the system is loaded). Any ideas what's going on?



tom-galletti asked
Matthias Lange - DE commented ·

3 Answers

AC Coupled PV Fronius 8.2 with a Quattro 15kv too slow to throttle

Quattro 15kv, Fronius Primo 8.2 with 7900w PV, 3 x Kilowatt labs 3.55kw modules, 2300w PV running thru a 150/70 Victron charge controller, Off Grid MG50

Maximum charge voltage of the modules are 54v and if they are fully charged and the AC PV is supplying 4000w with 4000w Quattro loads and the loads drop off, The system is way too slow to react in shifting the HZ to throttle the AC PV. (3 to 5 min)

I had to reduce the max charge voltage of the modules via the Quattro to 53v to allow a full volt of slow down time. Seems to be working at the moment.

Is there any way to increase the speed the Quattro ramps up the HZ to throttle the Fronius?

(I’m using the standard settings in the VE configure assistant to control the Fronius)

Should I Adjust Victron HZ shift values in the inverter to suit the Fronius values?

What are the correct Fronius Primo 8.2 inverter HZ shift values ?

greendovefarms asked
greendovefarms answered ·

2 Answers

Grid tie Ac coupled quattro 5kva and fronius 8.2.1 with color control


The fronius pv inverter does not generate power and stays on 0W.

It only generates if I switch it to slave but then I dont see it on the color control and I can not limit feedback to the grid.

I have an ac coupled system connected to the grid.

Quatttro 5kva with Fronius 8.2.1 connected to ac out and they are connected to the color control.

I have also installed a Carlo Carvassi et 112 meter and a bmv700 batt monitor and enabled it.

I have loaded ess and configured it and changed the fronius to mg50

The color control sees all devices and displays it correctly and shows fronius pv inverter.

I have set the color control to keep batt charged.I have disabled zero feed in and enabled feed excess power. Solar charger control voltage and current is off dvcc is off.

I have gone trough lots of document but did not find anything that solves my problem.

I would appreciate any suggestions.

Tnx @Guy Stewart

@Matthijs @Johannes Boonstra @Fronius Danmark

martinh asked
palom170 commented ·

2 Answers

Rule for Combining AC and DC coupling in off grid system

Hello @Guy Stewart (Victron Community Manager) and @Alexandra,

I would like to know how much DC coupling to apply in an AC off grid system for a well balanced system.

Does the amount of power to be installed on the DC side in an off-grid AC system depend on the capacity of the batteries? If so, what should be the power on the DC side, to avoid the batteries being flat? If there is a generator, is it necessary to add a DC coupling, or would it be interesting to start the generator automatically in case of low batteries?

Thank you

Deutch asked
Deutch commented ·

2 Answers

Sizing of PV power and PV inverter in AC coupling systems
Hello everyone, I'm working on the solar project and as my clIient is a bank I choose an AC coupling system.The problem is that with 1:1 rule, the energy of solar panels does not correspond to the energy demand.can I oversize the PV power of PV inverter?This will not creat a imbalance in the system    
as explained by the document attached?Thank you in advance

Deutch asked
stephanie answered ·

1 Answer

ESS Fronius Ac-In, doubt about shore current limit


Hello victron community members, I have a doubt about AC in grid limit

Currently in Spain, with the electricity tariff change we can hire 2 powers, so we can configure the ac in limitation of the victron depending on the schedule, I have a fronius in ac in and yesterday I did a test, by limiting the ac in input of the victron at 6A, once it reached that consumption in loads in ac out 1 it no longer generated more, it started to take power from batteries, is it fine? Is it not able to detect that this energy comes from the inverter? and not from the públic grid.

Thanks in advance.

palom170 asked
palom170 commented ·

1 Answer

Sharing my setup details for others to learn (JAG35 18650 + Victron gear)

Hi Folks,

A community is as good as the information shared by it's contributors so let me share my working setup for other to learns (and happy to further detail if not enough)

My setup consists of 2 banks of Jag35 (the famous youtuber) 10 times 7s 18650 cells with a Daily Li-ion 7s/24v Charge 30a / Discharge 60a BMS. (each bank has it's own BMS).

A Victron 100/30 MPPT smart solar charger (USB hooked to the Raspberry)

A Victron 24v battery protect

A Victron Raspberry PI (VRM Portal) monitor

A Victron SmartShunt (USB hooked to the Raspberry)

A Victron 24v-48v DC-DC juices a cheap Chinese Grid-TIE interverter

All wired accoording to the Victron Wired bible.

A set of 6 Solar 105w 4A panels in parallel. (Amp is King)

The weird thing about my setup, I'm hybrid.. I feed this to a cheap Chinese Grid-Tie inverter to my own home and as such consume all of it w/o returning it the bigger grid. (why doesn't Victron deliver a standalone grid-tie????) The BP protects the drain and returns to charge when needed.

This setup requires more tuning but it's working and it's a nice (home grown) hybrid kit.

Happy to share more details on the Lithium parameters but they are pretty standard.


(I'm LoRan nerd as well, hence the antennas)


robert-welling asked
klim8skeptic commented ·

2 Answers

Common Neutral in Domestic Situation

Hi All,

I need some solid engineering input on this question of making input and output inverter/charger neutrals common. I have seen the Common Neutral thread which is for a different application. This is a static application situation - a problem I have been battling with for over 6 years on all my projects.

It is essential to state the two key problem causes and why they are not solvable:

1. Our municipal grid has been degrading severely over the last 30 years with poor maintenance causing neutral disconnections and ground-neutral bonding issues on the utility/transformer side. This is getting worse due to utility having little finance and incompetent maintenance staff.

2. House wiring standards are not adhered to in many site cases meaning joins on neutral in ceilings/conduits for multiple electrical circuits. Or missing neutrals. To fix this (compliance issue) takes up a huge amount of time which customers are mostly not willing to pay for so I have found myself working hours, days, weeks and months for free to sort out these issues. Why is this a problem? Apart from the obvious electrical problems and neutral overloading, in my country customers cant afford to go off-grid so we split the house wiring into "inverter powered" and "grid powered" circuit (btw: we have daily power outages everywhere). Which means inevitably we will have a neutral fault or a common neutral somewhere in the wiring due to these non-compliant situations. So it may be worth common-ing inverter and grid neutral in the main distribution to "draw" the connection off house wiring - just a thought as the worst thing is to power a circuit without a neutral - our utility conditions has done us the honor of doing the "hands-on" test for us - to the detriment of equipment or lots of SPDs.

So my question: Is there any electrical compromise I can look into? - to stop me from sponsoring customer's compliance because of the nasty 80% of electricians who cheat and make lots of money.

Maybe some specific protective device or solution including common neutral, a specific SPD? some RCD that works -

* a 30mA RCD is not an option - electricians bypass them because of continuous tripping.

* off grid not an option as customers can't afford it.

* redoing site wiring not an option because customers can't/ don't want to afford it

* me quitting the business is a less than ideal situation as with 90% unemployment rate in my country other lines of work are just as difficult.

So to all the engineers out there who like solving problems please HELP! :D

P.S. I'm an Electrical/Electronics Engineer with more knowledge in Electronics than Electrical Power - I have fair experience with the effect of surges and earthing issues in electronics ;)


kenyon asked
kenyon commented ·

3 Answers


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