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Consumption readings not accurate - AC coupled system

Hi there Guys

I have an off grid system.

With a Quatro 8 kW and MPPT on the shed.

and a AC coupled fronius inverter on a house sub board 20 meters from the shed.

It seems that the consumption monitoring on VRM is not showing the gross consumption of the loads. Just the net. (after the fronius inverter has fed the load at the house).

Do I have to install a meter at the house sub board where the fronius inverter is to get a more accurate reading?.

Thanks for your help in advance


Regards Alex

Alex Manley asked
Alex Manley answered ·

2 Answers

Energy meter AC loads - PV = grid


I have two energy meters ET112's. Grid, PV array and loads both on AC in.

If the meter on loads is set to grid meter (wrong for mysetup) the ac loads is calculated as follow grid + PV = AC loads.

However it doesn't work if energy meter is set to AC loads ie AC loads - PV doesn't equal grid in VRM.

Is there a way to do this?



matt1309 asked
shaneyake commented ·

1 Answer

ESS setup for fronius on AC IN side

Hi all. Is it necessary to add in the setup of the Assistant ESS. That I have a pv on ac out if the pv is on ac in ? I ask the question because I have a small problem.

System design 3 phase multi 48/5000/70 with fronius symo 8.3-2 ( 7.0 kw pv panels) on ac in side.

In the ESS Assistant I answered no acpv on out side.

During mid day the fronius is showing production on 8.2 kw even if the pv panels are 7.0 kw... can someone tell me where to look at ?


Can I set somehow to be 7.0?

mihaimicu asked
marekp answered ·

2 Answers

Solaredge SE27.6K on Multiplus-II AC-IN

a short questions about the Solaredge SE27.6K Inverters with 3Pcs Multiplus-II (3-Phase System with about 10kWh Battery).
Is it also possible to use the Solaredge SE27.6K on the AC-IN Port of the Multiplus-II ?

like here, but connected to AC-IN:


The PV System with the Solaredge SE27.6K is already installed, the ESS with Multiplus-II, Cerbo-GX etc. have to be added.

Because of the 1.0 Rule, the Solaredge SE27.6K can not add on the AC-OUT of the Multiplus-II.

I know if the Public Grid is down, then the PV Generators also not work, but this would be no problem for me.

joergsc asked
markus answered ·

1 Answer

MULTIPLUS-II 48/3000/35 im Inselbetrieb / AC-IN

Hallo zusammen,

ich habe wohl doch nicht den richtigen Durchblick.

Ich verfüge über jeweils 2 Module (275 WP pro Modul) in Ost- und Westausrichtung. Ursprünglich habe ich pro Modulpaar mit Letrika netzgeführten WR in das Netz eingespeist. (Funktionierte auch ca. 4 Jahre ganz gut). Ein Stromausfall hatte mir letztes Jahr 1 WR (Letrika SMI 260) geplättet und da ich eine Insellösung anstrebe (evtl später gekoppelt mit einem Kleinwindrad) empfahl mir greenakku den Victron Multiplus-II 48/3000/35. Der Zukauf von 4 12V Batterien in Reihe ermöglicht mir die Einspeisung als Insellösung. Das klappt auch. (Kühlschrank/PC/Licht/Fernseher). Der noch funktionierende netzgeführte Wechselrichter (Letrika Westseite) orientiert sich ebenfalls an dem AC (50Hz) des Multiplus und gibt weiterhin Strom ab. (Leistung am Multiplus-AC-ausgang verringert sich, wenn auf der Westseite eingespeist wird) Da der Aufladevorgang mit 2 Modulen an 4 Batterien (150 Ah) ziemlich lange dauert würde ich gerne über den AC-Eingang des Multiplus II den vom Letrika überschüssig erzeugten Strom nutzen (wenn der Kühlschrank nicht anspringt, ich keinen PC eingeschaltet habe usw), um die Batterien zusätzlich aufzuladen. Das klappt bisher nicht. Kann es sein, dass der VICTRON im BULK-Vorgang keine Frequnz mehr zur Verfügung stellt und eine Netzfrequenz erwartet, so dass sich der netzgeführte Letrika dann im Inselbetrieb abschaltet? Schaltbild anbei. Ich hoffe, das jemand hiermit etwas anfangen und mir weiterhelfen kann.


G. Berger


gberger asked

0 Answers

Where does excess power go in microgrid setup

Hi All, noob question here.

I'm designing a system whereby I have a microgrid.


Grid -> quatro/multiplus with batteries connected -> house circuits -> grid tied inverter

I'm however struggling with some logic.

Say the real grid goes down. My system above should continue using the batteries and grid tied inverter (if wired correctly and assuming my understanding is correct)

However say the grid goes down and my batteries are full and the grid tied inverter is still pumping out energy.

Do I need to setup grid limiting on the grid tied inverter or use a specific supported grid tied inverter to prevent this scenario ever happening? If not where does that exercess energy go given batteries are full and grid is offline?....

The growatt grid tied inverter I have does support grid limiting I believe and would connect to a meter measuring house loads to determine how much power limiting to implement. However I don't want this setting enabled all the time as if the grid is connected I'd like to sell the excess back to the grid. I can maybe get creative with raspi RS485 adapter and python and right a script to enable/disable the setting if grid goes down. (however I'd desperately need to up my python abilities for that)

If grid limiting isn't the solution to the above then I'm completely lost as to what happens to that excess power produced by the grid tied inverter. Would greatly appreciate either an explanation or direction on what resources to read to find the answer.



matt1309 asked
Rob Duthie commented ·

1 Answer

3 phase AC-Coupling system with Quattro+HUAWEI.

I'm designing a 3 phase AC-Coupling FV system with 3 Quattro of 15kVA + 40kW HUAWEI for an off-grid use. My question is regarding power. Let's say that the day is sunny and the batteries are full, what happend if the load request 50kW to the system. Can we consider that the HUAWEI provides 40kW and the rest will be provided by the Battery Bank throuhg VICTRON? In such case, can we consider that the power can we added? Can I say that finally the system support 80kW in a certain conditions (sunny + full battery)?


Ernesto asked

0 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

Off Grid Installation AC Coupled Fronius Disconnects with Back Up Generator Is Switched On


I have installed Quattro 8kva with 8kW Fronius AC coupled with a CCGX 800Ah of batteries. It is an off grid installation with PV inverter assistant on. When I switch on my generator and the Quattro synchronises with it the Fronius inverter disconnects and says error code 107 which meant no grid.

My generator is 4.5kVa but the wave form is poor so I have limited the current to 13amps and I have used the Weak Ac function

From what I have read about the off grid systems in victron literatureI thought that the Quattro would control wave form so the Fronius and Generator could both power the loads and charge the generator.

But from reading other posts it seems the Quattro is just passing the generator AC frequency through and it’s too messy for the fronius to sync.

Is there a way to allow my generator and fronius to work?

tunde-olaoye-1 asked
jon-lowbank answered ·

4 Answers

Active BMS, MultiPlusII, How to stop Charging...

Hy all!

I read hundreds of pages, but it seems i haven't found the right answer.

I have a 3 Phase MultiPlusII 48 3000 35 System, with AC Couppled 5kW Inverter, an DC couppled MPPT and a DIY 48 V 260 Ah Battery Bank with active BMS.


-- this picture shows the system with battery Cut Off...,

My Problem is, that the Active BMS has no interface to any System, so I used an RaspberryPi, read the "Console" and write to the Colour Control GX via Modbus some data like SOC.

I even tell the MPPT and the PV inverter to stop Charging, when the System is in Island mode (ModbusTCP).

BUT.. when the Grid is connected, I can not tell the MultiPlus to use all available Energy to feed back to grid until the BMS shuts the Relay off itself ...

I am able to stop Charging the battery, but then the Multi does not use any power from the Battery ???? and I can tell the MPPT to stop working (all done via ModbusTCP)

My question is:

Can I stop Bulk and floatcharging via ModbusTCP? or do I have to make different settings?

The System knows the SOC, and i do not need any constant current. and so on.

Important: there is an active BMS. it shuts it's relay off when 100% is reached. no overshooting, no burning energy..

What I want is, that

when charging, and the soc is > 95 % the Charging Power to the battery should be reduced to 0 when 100 % is reached.

all access Power should go back to the grid.

when there is no grid, the Chargers should reduce themselves to 0

Please give me some Info / help

Bernhard Matschinger asked
alfonsohera commented ·

3 Answers

Reverse Power to Generator in AC Coupled Off grid System

How is reverse power flow to generator controlled in AC Coupled off grid Multi and Quattro Systems?

allaboutsolar asked
Guy Stewart (Victron Community Manager) commented ·

5 Answers

Setting up an AC coupled system with string inverter Aurora 6 kW with Multiplus or Quattro


I have a customer which already has a grid tied system using 27 modules of 230W and 1 string inverter 6 kW Aurora model PVI-6000-OUTD-US.

I understand that CCGX has built in a FRONIUS module for AC coupled systems and I have the doubt for other models that can be compatible and if there is an specific software product from Victron to do it.


dgmar-ni asked
oswaldoaguirre2020 commented ·

2 Answers

DC Generator as input for SmartSolar 150/85

Hello community!

First time user of Victron products. So a big hello to all.

We needed a charge controller in tandem with our new DC Generator model to have the abilty of charging all battery chemistries, with the added features Victron has to offer in that range.

So we decided to test a SmartSolar 150/85 with the dc generator as a replacement to pv input.

Not knowing if it would work or not, we are pleased with the results! Firstly, no magic smoke(thank God for that). Generator started automatically when LiFePo4 batteries reached a preset low SoC. We used a 48v 100ah bank for the test. The generator produced 70vdc @ 40A(limited for the testing). SmartSolar did the job as expected!

We will continue testing over the next few days and upload a video of the end results.

The main purpose of our DC Generators is to be used as a backup source in case of low solar production in off grid situations, telecommunication sites, boats, rv's etc.

All of our dc generators and AutoGen controllers connect through wifi and can be monitored via our mobile app.

So now, Victron can add DC Generators to the solar, wind, hydro list of input sources to their MPPTs.

dc-generators asked
dc-generators edited ·

2 Answers

Frequency shift too slow in the Quattro+ BYD battery +SMA SB solar inverter system


Running the Quattro with L series BYD battery (14kw) results in the battery shutting down, due to the Quattro taking extremely long time to start shifting the frequency (around 8-9 seconds from the point of BYD charging limit going to 0, utill the Quattro frequency actually start to increase)

I know the L series batteries are not current meant for the off-grid applications, but they are advertised for the backup applications, in which case Quattro has to be in position to adjust the solar inverter on time in order to prevent the battery overcurrent, should the grid fails during the day

Any suggestion if this problem can be fixed, or has a workaround ?

With best regards,

Oleksiy Frolov

fanda-eu asked
fanda-eu answered ·

2 Answers

Multiplus II GX wiring to generator (AC-in)


In the MultiPlus II GX manual it is written to follow the instructions below when connecting the AC input:

Left to right: N (neutral), PE (earth/ground), L (phase)

In my setup I have a 3kW inverter generator as AC in, but I cannot understand which is the neutral and which is the phase as the output of my generator is a female plug, on which the plug can be inverted from time to time.

Which is the proper connection in this case?

Thanks a lot

the-salmon asked
the-salmon commented ·

3 Answers

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