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AC PV Coupling

Is there a way to test the frequency shifting that controls AC coupled inverter?

I have a on-grid inverter made by Spirvent.

Unfortunately this maker does not exist any more and I cannot get any reliable info about it now.

It still works so I would not want to spent money on the new one, just to be sure that it will work in AC coupled configuration, because it is on the Victron approved list.

Is there a way to test this Spirvent reaction to frequency shifting other than connecting it on AC out and waiting for the moment that MultiPlus-II will need to lower inverter output and starts shifting the frequency?

MarekP asked
MarekP edited ·

2 Answers

Cyrix ct120 + Blus smart IP22

Bonjour, Dans mon van j'ai une batterie de démarrage et une batterie auxiliaire reliées par un coupleur-séparateur Cyrix CT12. J'ai installé un chargeur Blue smart IP22 à ma batterie auxiliaire, quand elle est chargée à 100% je pensais que le coupleur permettrait au chargeur de charger ma batterie de démarrage mais il ne le fait pas. Avez-vous une solution ? Bonne journée à tous Arnaud

Thierry Cortassa (Victron Energy Staff) answered ·

1 Answer

Sub-50Hz compensation in PV-Inverter support

PV Inverter support uses frequency shifting to steer PV Inverter output on the AC branch.

This works very nice and reliable with Fronius inverters in our nstallations.

However, this frequency shift works only in the 50Hz+ range, there is never a compensation below 50Hz:


Now all devices in the microgrid that take these 50Hz as source for their internal clocks (actually quite a few do - e.g. microwave oven clocks) start to get ahead of time noticeably within a month.

Wouldn't it be possible to implement a sub-50Hz compensation in the nighttime to counter the effect that accumulates over daytime?

As soon as e.g. the Fronius switches off for the night, there shouldn't be any adverse effects to lower network frequency to 49.5 or so.

According to our measurements, the clock skew can be as much as 0.8% per day - so I'd really appreciate if the assistant had some compensation measures built-in.

PS: If I choose "50Hz" as tag, it gets converted to "EasySolar All-in-one". ???

PetaJoule asked
Guy Stewart (Victron Community Manager) commented ·

0 Answers

Victron QUATTRO 48/5000VA with SMA 5000TL Inverter in Island mode

Hi, I have an existing grid-tied SMA inverter (SMA 5000TL) and 2 strings of 13 panels for total of 6.5kW. I want to add storage and am considering the QUATTRO with 4 x Pylontech US3000 batteries (@48V nom).

The main aim of the exercise is to be self-sufficient in case of extended/indefinate grid outage. I am no expert, but my reading suggests that the Victron QUATTRO would provide a mini-grid on the AC-OUT-1 and that the SMA solar inverter would run 'normally' on this channel regardless of whether the grid was connected or not.

Assuming that the above is correct, would the SMA inverter connected in this way be a stable and reliable configuration. I ask this because I have read some posts/articles that indicate that there are situations where the inverter may go over-voltage and shutdown the QUATTRO.

Is this a potential problem, and what would be the recommended way to deal with this?

Note, the loads would include 1000W and 1500W pumps (bore pump etc), inverter aircon, fridges and freezers, lighting and misc.

thank you,


rrroonn asked
ejrossouw answered ·

3 Answers

AC Coupling with Autotransformer


I currently have a 15kw Quattro with a 100A Autotransformer on AC Out 1 to provide power to a distribution panel. I want to attach my solar PV to AC Couple the system. The Quattro and battery size both satisfy the factor 1 rule... What I'm wondering is if I can I attach the PV between the Autotransformer and distribution panel? or does it have to be attached in between the Quattro's AC Out 1 and Autotransformer?

Thanks for any help.

Bishop8 asked
WKirby answered ·

1 Answer

AC Coupling - is Quattro 15k compatible with 72x M215 Enphase Micro-inverters?

Hello, I'm interested in AC coupling our grid tied solar system with a Victron Quattro 48/15000/200-100/100

System specs:

Solar array is 72 panels with 72 enphase M215 microinverters all in parallel

Each microinverter produces 240V @ .9amp each at 60Hz

Peak kW is usually 15kWp, occasionally 16kWp

Can the quattro handle all of that PV? Thanks for your time and help.

Bishop8 asked
Bishop8 answered ·

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

AC Coupling with non-Fronius inverters and export power limiting

Hi All,

Here in South Africa we are more often than not, required to prevent power being exported beyond the Meter (Grid).

We often encounter homeowners who have already invested in a solar power system, with some form of grid-tied inverter installed.

The typical upgrade involves installing MultiPlus or Quattro Inverter/Chargers with some form of lithium battery bank.

The question arises with regards to how we incorporate the existing grid-tied inverter?

If it is not a Fronius inverter, then we cannot use the "Fronius Zero Feed-In" functionality through using a single energy meter (Carlo Gavazzi ET112 or ET340).

If we retain the existing grid-tied inverter's export limiting device (current sensor or energy meter), and continue to implement an energy meter for the Victron system, then how should it be set up? Which device should be installed first in line? Should we set a buffer/threshold on one of the systems to ensure that they do not compete to achieve grid-power = 0 (or other set point)?

I foresee that the two different export limiting control systems will compete against each other and may result in instability and/or poor performance.

Any insights into this?

Nicholas Herbst asked
Aleuli answered ·

2 Answers

3 phase AC coupled PV for backup or off grid without phase balancing?


I am planning a three-phase installation with Three Multiplus II 5kVA with a SMA Tripower 8kW on AC out. The system will run in ESS with backup functionality.

When taking the three-phase Victron training I found this statement, which was new to me:

"A three-phase system can not aid in phase balancing during charging. Each unit will always equally charge the battery"

This really worries me regarding backup or off-grid use. Could this prevent AC PV from being useful for charging the batteries, or even working at all? I assume that three phase PV inverters will try to deliver equal power to all phases, but what happens if one phase (e.g. L1) is heavily loaded and the others are not?

I would have assumed this scenario as an example:

  • L1:Fully loaded, PV supplies 2 kW to load. Cannot charge battery.
  • L2:No load, PV supplies 2kW to battery
  • L3:No load, PV supplies 2kW to battery

But with the equal charge current rule it seems like the follwoing example is instead the case, where PV power cannot charge the battery during phase load imbalance:

  • L1:Fully loaded, no power left to charge the battery
  • L2:Cannot receive PV charge since L1 cannot charge
  • L3:Cannot receive PV charge since L1 cannot charge

This would seem reasonable enough, but what worries me in this example is that it also seems to mean that the SMA inverter is then expected to deliver power to three very differently loaded phases. I am not certain that it has the specifications to handle that.

It seems to me that to make the backup/off-grid use case viable, either the PV inverter or the three phase Multiplus system will need to do some phase balancing!

Am I right? How does this work in real life? Is it possible at all?

S_Forsberg asked
S_Forsberg answered ·

3 Answers

Multigrid and enphase


I had an enphase IQ system configured with a no-export profile. Just added a multi and ESS assistant, programmed the enphase to generate without limits. Problem is when the scheduled charge kicks in at 10am. The multi does not limit the charge based on Panel generation. It just use all power configured on the ESS "Maximum charge power" settings.

Is there any way to use the surplus power from the panels only?

Cheers and thanks for any info that can be given.

Aleuli asked
Aleuli answered ·

2 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
alfonso.hera commented ·

3 Answers

Turning individual PV inverters on & off

Hi all,

It would be useful if I could disable PV inverters individually via VenusOS. This is particularly useful in off grid system when the batteries are (nearly) full and there is not much load. When a sufficiently significant load would appear, the PV inverter(s) can be turned back on, of course with some hysteresis applied. The idea is that the PV inverters are responsible for the bulk of the charging but, as charging via a Multi is a bit "clunky" (not my words, but Victron's :-) ).

It is possible to disable/enable all PV inverters via com.victronenergy.vebus.ttyUSB0/PvInverter/Disable. I assume VenusOS achieves this by telling the Multi to raise the frequency to the value as specified in the PV assistant parameter "The PV inverter will disconnect when the frequency is higher than".

There is also com.victronenergy.settings/Settings/Fronius/Inverters/<serial>/IsActive for each individual PV inverter but as expected this disconnects the PV inverter from VenusOS but doesn't stop it generating power.

Is it possible to turn individual PV inverters on & off via VenusOS using dbus or MQTT?


jbakuwel asked
jbakuwel edited ·

1 Answer

AC Female plug adapter coming from controller?

I have a mppt 100/20 (48v) controller. I was wondering if there is a female AC plug adaptor available that could use to plug into my minnkota 48v battery system AC converter charging unit. If so, do I plug it into battery or load on the controller?

CAdams asked
CAdams commented ·

3 Answers

AC output issue Multiplus 12/2000

Hi, I seem to be experiencing an issue on the AC side of my Victron Multiplus 12/2000 Inverter. It utilizes 400W of Solar PV, the MPPT 100/30 Charge Controller, a 200AH lithium battery bank and a lot of wiring components in a frustratingly confined compartment. I have combed through the system referencing the design from Explorist.Life ( I used, have tested for shorts, faults, polarity, circuit continuity, OCPD integrity, tourques, voltages (34VDC from solar, 14.4 between battery terminals and busses, 120VAC from distribution panel) and nothing seems out of sorts to me. The DC side of the system appears to work fine, but I am stumped as to what could be causing the inverter to throw an error every time I turn it on, and why it will not produce any AC output to distribution panel.

Has anyone experienced a similar problem? Have I overlooked something obvious? Any advice appreciated.

Here is a short video I made for an overview of the problem:

zamigill asked
zamigill commented ·

5 Answers

documentation "Integrating with SolarEdge" work around


in the application note "Integrating with SolarEdge" it is written :"Note: APS mode is mandatory for systems requiring both zero feed-in in on-grid mode and frequency shifting in off-grid mode."

  • I can confirm that for SetApp inverter with firmware CPU 4.9.33, (DSP1 1.0.1036, DSP2 2.0.910) and country settings Spain & Italy when in APS-mode the settings in corresponding P(f) are being ignored, no power reduction on rising frequency occurs.

  • For country setting Spain: Power Control-->Active Power: P(f) is not available

Frequency shifting in off - grid mode is desired and I get a P(f) reduction when using country "Italy" according to the defined ramp P(f) in "Active Power". However there is a hysteretic lock, frequency needs to fall back to 50Hz again + some hold time until a new reduction cycle is started. (A wakeup gradient to improve system stability is defined though: (200ms))

@fjlacock is this hysteretic behaviour of P(f) also the case when in APS -mode? Apart from the extended trip values in APS mode, is there a difference between P(f) in that mode and “P(f)” in “Active Power” + default country mode?

Thank you!!

IERTigre asked
fjlacock answered ·

1 Answer

AC coupling and frequency shifting down

I have a grid-tie inverter that can regulate power with frequency shifting but only when frequency is shifted down 5%. (47.5-50.0Hz).

Can it be used in AC coupling setup?

MarekP asked
MarekP commented ·

3 Answers

AC Coupling and BYD premium LVL 15.4


I would like to know if there is any possible way to speed up frequency regulation by modifying the settings of the PV inverter assistant.

The system is off grid and consists of

- BYD LVL premium 15.4

- Bluesolar MPPT 150/60

- Quattro 48/8000

- Solaredge SE6000H (maximum expected PV-contribution is << 4500W)

The P(f) ramp at the Solaredge side is defined from 50.2Hz to 51.7Hz and disconnect @ 52Hz.

The Victron PV-Inverter assistant is configured for the same band with disconnect @ 52.1Hz. With 6000W inverter and 6400W PV.

I observe that once 55.2V are reached BYD sets the charging parameter to zero. However charging continues as the frequency ramp only rises slowly and therefore the SE inverter does not reduce its output fast enough. For now I throw off (via AC-OUT 2) the SE inverter once the voltage gets higher 57V. By that time frequency has only risen to 50.4Hz. Can the ramp rise time be shortened? Am I too carefull with the 57V limit? (cell details show almost 3.8V for the highest cell). Thank you in advance for your help and input!!

IERTigre asked
IERTigre commented ·

1 Answer

PV Inverter assistant. What effect do the settings have on frequency regulation?

I use the PV-Inverter assistant in an off grid setup with lithium battery. At end of charge when the BMS doesn´t admit more charge, the battery voltage still rises more quickly than the Victron increases the frequency. This leads to an unstable system. Therefore I try to tune the frequency response of Victron by adjusting the values in the PV-Inverter assistant. Especially I would like to understand the effect of the values "PV inverter power" and "PV panel power" on the frequency regulation.

IERTigre asked

0 Answers

AC Coupling with Solaredge, requirements for pure off grid


currently I am setting up an off grid PV-system and try to integrate AC coupling with Solaredge SE6000H and Quattro 48/8000. (Battery is BYD premium LVL)

I followed the instructions in Victron documentation: Integrating with Solaredge

The only difference is: There is no public grid available and zero feedback is not required. Therefore no Solaredge Energy Meter is installed.

My question: is the use of the Energy Meter mandatory for the correct working of frequency based power reduction by the SE inverter?

Which country settings (on the SE inverter) did you use in your test environment?

I ask, because my test run failed.

First I used "Spain" as country setting and noticed, that in the SetApp Power Control-->Active Power the P(f) menu was missing. I reconfigured country settings this time to Czech Republic 16A and was curious to see that P(f) was back again.

(Although I doubt, that this setting is at all relevant for my setup as I will not be working in that specific country mode, but in APS (Alternative Power Source) mode.

But to follow the documentation I set P(f) in both menus: In Power Control-->Active Power-->P(f) and Power Control → Alternative Power Source → P(f) and ranging P0 100%@ 50.2Hz and P1 0%@ 51.2Hz.

On Victron side I use the assistant PV-Inverter and with the same tresholds and disconect @ 51.5 Hz.

However the test run failed. (And yes, SE status said I was in APS mode). No power reduction on SE-side happened. Victron modulated the frequency up to 51.5Hz and luckily and thanks to the relay assistant and SE on AC-Out 2 it got thrown off when BatV got too high.

Thanks for any inspiration!!

IERTigre asked
IERTigre answered ·

2 Answers

AC coupled inverters that work with frequency shift (Solis?)

Hi Im after a list of brands that work with frequency shift to reduce output. Ive used fronius before that works well and ive heard SMA will aslo work, im wondering what other brands people have had success using, in particular im trying to find out if anyone has managed to use a Solis inverter as cost wise this would be great. Thanks

jacko asked
WKirby commented ·

6 Answers

ac coupling easysolar

I read that the easysolar system incorporates a multiplus. As multiplus allows ac coupling does this mean easysolar also allows ac coupling?

stephenjdrew66 asked
Daniël Boekel (Victron Energy Staff) commented ·

2 Answers

AC and DC coupling - Co ordination

I just watched the webinar for Victron/Fronius Micro grids.

I want to understand what happens when the Fronius inverter is ramped down through the frequency control.

There are two parts to this question which are closely related.

First question is simple.

Can a common PV array feed both the string inverter and the Victron solar charge controller? So they would be connected in parallel and share a common dc energy source.


Let's say the house is only using 200 watts. Let's also assume we are using a 3KW fronius string inverter. The PV array is producing 4KW and the battery is 50% SOC.

Once the fronius inverter ramps lowers its output through frequency control can the solar charge controllers demand more of the PV energy and send that energy to the batteries?

project eco asked
jbakuwel edited ·

4 Answers

AC coupled with ingecon and MultiPlus II

Hi. I have a multiplus II 48-5000. On the AC out 1 i have a ingecon sun 1 play with 5kw of solar. I'm using the em24 meter. All firmwares on multi, Venus and ingecon has been updated. Ingecon and Venus on the same network. ESS has been loaded. Under PV Inverters on the Venus I don't pick up the Ingecon grid tie inverter. Can somebody please assist. asked edited ·

0 Answers

AC coupled DC coupled system output


In an off-grid AC coupled DC coupled system utilising a fronius primo 4.0, and a victron Multiplus II 48/5000.

If the demand exceeds the Primo string inverter, does the Multiplus II 48/5000 come in to increase/add to the total amount of output power available up to its maximum potential?


Drae asked
SebastianLehmann answered ·

1 Answer

How can I cut off AC-Out 2 in an AC-PV Coupled System based on Battery SOC?
  • From one of the recent vidoes on the Victron Professional trainings, "Coupled AC PV Inverter Introduction", @ Guy Stewart talked about the Optimal AC PV off-grid configuration and that would fix a challenge I have at an off-grid site that has AC-PV Configuration but no DC. Please how will I configure AC-Out 2 to cut off when the battery SOC goes lower than a particular threshold. Will I use virtual switch?
  • The system is actually working fine, it's just that once in a while when the batteries gets drained, and the Quattro shuts down, the Fronius Inverter can not come up until the generator is put on. Adding a charge controller and solar panels will fix this but the client isn't ready for such expenses yet.
  • On that site I have installed:
  • 5kVA Quattro
  • 5kW Fronius Primo
  • 5000Wp of solar panels
  • 13.8kWh BYD
  • CcGX
  • I'll appreciate any help I can get from @Guy Stewart or anyone who knows how to do this. Thanks

Vicstix 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

0 Answers

AC coupling with Y600 or QS1200 micro inverters in Split Phase

I live in Mexico, I have Apsystems micro inverter 220v Qs1200 and YC600 and I was wondering what type of Multiples would fit an AC coupling system.

My concern is because Victron units are single 120v, and my back up panel would also be 120v, but the grid tie inverters are 220v.

How this function? What I am missing.

Can you recommend me which Multiplus would be ideal on this case?

I plan to buy 2.5 to 3 kWh storage battery.

SebastianLehmann asked

0 Answers

Somebody Installing this Ac Coupling System? Grid connected. For zero feed-in .

Hi Gentelmens .


Please help to me for to have an a system to working properly.

All Symo are upgraded to the last Firmware .

The Grid connected (#2) Slave Symo 8.2 (light) is without datamanager witch is connected to the Victron Ac1 in . grid setting is Country code (Romania)

The (#1) Master Symo 8.2 (web ) is with datamanager witch is connected to the Victron Ac1 out. grid setting is Country code MG 50 .

In this situation: the (#1) Master Symo 8.2 is always in braked by Victron when zero feed-in on .


When I switch off the zero feed-in ..this Symo go to give the power from Pv.


If you see nonsense don't working the booth (#1) Master Symo 8.2 because the battery is low

What is a right settings in this situation? from Fronius side and from Victron side ? because I don't want to feed-in any power to Grid from both Inv Fronius Symo


Gabriel Tanasescu asked
Gabriel Tanasescu edited ·

0 Answers

Help with PV inverter on AC-out Multigrid

Hi, could anyone help me with connecting a SE2200 (Solaredge PV inverter) to my system on AC-out of the MUlti: System: Multigrid 24/3000/70, SmartSolar MPPT150/70, BMV 702, Venus GX, 4xTelecom 400Ah batteries.

The only thing I would like to find out for now is the way to add the PV in the system. There are so many variables that I lost my way. This is how it looks now. You can see that the PV-inverter gives energy, but the unit is invisible in the scene.


Venus and SE2200 share the same WIFI connection.

Any help is appreciated.

Kind regards, Henk Volkers

Henk Volkers asked

0 Answers

Reverse power to Grid in AC Coupled System

In AC Coupled PV systems using Fronius and Victron inverters, I have observed that at times when Grid is available and solar yield is higher than is load demand, the excess is shown to be going back to the grid. How can this be prevented as setting for Quattro inverters and Fronius is no grid feed in.

This is quite a serious issue as Grid feed in is not permitted in my country.

@Guy Stewart (Victron Community Manager)

Daymie asked
Girbar answered ·

1 Answer


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