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AC PV Coupling

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 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

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

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
Bernhard Matschinger answered ·

3 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

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

Minimum Battery Requirements Again! How is it calculated? A thread to clarify this for good


I have looked at the other threads but they are all project specific so I decided to get some information on the minimum battery sizing requirements as listed by Victron for AC coupled systems. The 1.0 factor rule is well explained but the battery storage is not well explained.

In section 3 here: they say that you need a PV:Storage ratio of about 1kW PV: 5 kWh or 1.5kW PV:5kWh

For Lead Acid:

1 kWp installed PV power requires approximately 5kWh of battery:

  • 100 Ah accubank 48 Vdc

and for Lithium Ion:

1,5 kWp installed PV power requires:

  • 100 Ah accubank 48 Vdc

Could I please get a detailed response to this maybe with an example (also for the future readers of this thread) so that the reasoning can be understood? In some places it says 'for system stability' in others it says 'for battery lifetime'. Neither is a very good answer for an otherwise detailed knowledge platform.

My thinking on this:

Assuming the batteries could get charged by full power in an uncontrolled manner through the AC coupled PV inverter, for a 1 kW PV to a ~5kWh Battery@100Ah/48V, you would be charging at about 0.2C which is low enough. And for Lithium Ion at about 0.3C which is also quite low.

What would happen if we only had for e.g. 5kWh Lead Acid for 5kW PV output? The charge rate would be 1C, which is high for lead acid but not dangerous.

So what am I missing? Why such a high minimum battery capacity? If the PV power is high enough and the battery is only used to form the grid (but not discharging much since the load is met by PV), then it would be good to save money on storage and instead invest it on PV.

Thanks for spending your time on the answer and for sharing your knowledge.

Stay safe!


Muzungu asked
Muzungu commented ·

2 Answers

Multiplus II having different frequencies in ACin and Acout1

I have the following setup:

1xMultipluss II 48/5000

1x 5kW grid tied PV inverter connected to the ACout 1 of the Multipluss II

1x BYD B-BOX 10 battery

Grid is conneted to the ACin of the Multipluss II and the grid tied PV inverter and loads are connected to the ACout 1. The Multiplus II is configured as an ESS system.

My problem is as follows: If I physically disconnect the grid from the ACin, the system works perfect. If I connect the grid to the ACin, what happens is that frequency in the ACout1 starts to change and the grid tied inverter stops inverting since frequency is out of range. This happens at any SOC of the battery and even at night when the PV invertir is not working. As long as I understand, ACin frequency and ACout1 frequency shoud be always the same, but this is not the case. Frequency variations goes from 48 Hz to 53 Hz (big changes in short time). I can also see the LEDs flikering sometimes. The main problem is that the PV inverter stops inverting due to changes in frequency. Does anyone have any idea why this is happening and how could I solve this problem. Thank you in advanced.

Julian Monedero asked
Daniël Boekel (Victron Energy Staff) commented ·

5 Answers

Can PV power from a grid tied inverter be regulated to optimally charge batteries if connected on AC input.

Good Day

I have been looking through the various manuals and assistants on the Victron website and forums but i am still not sure if the configuration i desire is achievable .

I currently have a Solaredge 3 phase grid tied inverter which has 7kw of panels connected to them. This was my initial setup which did not have any battery backup and any additional Pv produced was fed back into my local grid for which i received a credit . ( installation was November 2018).

Load shedding has become a serious issue in South Africa and the need for backup became increasingly important. I then installed 2 x off grid 5kva Axpert inverters with an additional 6kw of panels and 7 x 3.5kw pylontech batteries (24.5kw in total ). We separated all loads requiring backup to a single phase and the inverters were connected in parallel. Pumps , underfloor heating , water heating elements are connected to the other two phases still.

To cut a long story short i was extremely disappointed with the inverters performance and functionality and i have decided to replace them with 2 x Multiplus ii 5000 inverters. I will purchase the other additional items like the MPPT , cables , ET340 meter, etc. From my understanding the Cerbo ( still due to arrive in SA by end of May ) would be used to control the whole system and everything links into them.

Would the Victron system be able to differentiate between Power that is bought from the grid and PV power from my Solaredge inverter on the AC In side of the Multiplus to regulate the amount of power used to charge the batteries . Ideally no power from the Solaredge inverter should be fed back into the grid if it can utilize the PV power more effectively to charge the batteries.

I have noticed that the Victron inverters can receive PV data from the Solaredge inveter. Can this info be used to optimize self consumption or would the data be purely for viewing .




Khalied asked
Daniël Boekel (Victron Energy Staff) answered ·

1 Answer

Off Grid DC Solar/Batteries with added AC Solar

I understad that an off grid system with DC solar, batteries and an inverter/charger can be be connected to a (rule of 1-1) AC solar/inverter system via the AC OUT on the DC inverter/charger, but this limits the size of the AC solar to the same size as the DC inverter/charger

CAN AC Micro inverters/solar be connected to the AC IN on the DC inverter/ charger to increase the overall size of the system? e.g. acting as if the DC charger/inverter was connected to the mains grid.

Steve Eggleton asked
Guy Stewart (Victron Community Manager) answered ·

1 Answer

(On-grid) generator+grid management with AC-coupled PV

Dear All,

I've seen several topics on the matter, which I duly noted for when commissioning will come, but they did not really answer my question :

Let's say there is grid on AC-in 2 and generator on AC-in 1, and AC-out coupled Fronius inverter, feeding excess PV power to grid activated.

Does the CCGX automatically deactivate feedback to AC when the generator is ON (AC-in 1) ?

Or does it consider a single AC bus to feed back to, and then I will have to install my own reverse current protection device at the generator output? (Or install the PV on AC-out 2, opening relay when AC-in 1 is ON, as explained on other threads)

Thanks in advance!


Qcrambes asked

0 Answers

0 Answers

How to connect multiple Fronius to the GX Color Control?

Dear All,

Please help me how to solve this configuration.

we have installed 33KWp system with three 10KW Victron quadros and 3 Fronius symo 10KW. everything is working perfectly.

the only thing is How to connect the Fronius to the GX Color Control?

Thank you


Abdulbasit asked
MaHa answered ·

2 Answers

AC coupled system cold start

Assume a Multiplus with a battery and an ac coupled Fronius Primo in an Off grid situation.

Can the system recover from a completely no power situation (battery discharged, no ac grid) or is the system in a deadlock then even if the sun is shining?

jmtatsch asked
Matthias Lange edited ·

1 Answer

Quattro 15kVA and Huawei SUN2000 100KTL M1

Hello All,

I want to embark on a project with 3x15kVA quattro and 1x100KTL M1 Huawei string inverter. I live in Nigeria where feed-in is not practiced. Is this system combination possible? Has anyone ever done anything like this before?

Regarding feed-in, since zero feed-in is only possible with Fronius, i am thinking i should be ready to feed-in the excess of my PV production to the grid (though not practiced here but i don't think it is a crime yet). Will this affect the stability of the system?

Thank you

Alakandee asked

0 Answers

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 commented ·

1 Answer

Solis PV inverter and AC coupling


I recently installed a new Solis 3 Kw PV inverter coupled to the AC output of a Victron Multi. The Multi is ramping up the frequency when the battery is full, as set up in the "assistant". The Solis does not respond to frequency rise, and continues to supply power and over charging the batteries. I contacted the seller, and Solis tech help, to ask what settings I should use to make it happen. They tell me the version of the Solis made for the UK market does not support the frequency derate option. On this Solis home screen it says LimByFreq which I took to mean what it sounds like. My quetion for you is : Do you think this is right ? If you are UK based what settings did you use to achieve the power control ?

Robert Bazalgette asked
Paul B commented ·

2 Answers

AC coupled STATE 453 Short term grid voltage error

Hi, we have two similar systems on the property. One works well, the other does not.

1 x 5K coupled Primo/Multiplus (works)

1 x 3K Coupled Primo/Multiplus (never has worked well)

The 3K Multi makes a very odd crunching (humming) noise when charging (as soon as the primo is turned on). The MP begins to charge then the primo shuts down with various error codes (Error 456) being the most common.

NOTE: it does not make the same sound when charging form the AC input (Geni)

The MPlus has the PV assistant installed as per Victrons recommended settings. The sound the MP inverter is making sounds very unhealthy, but it's made it since day one and I was advised by the sales rep that it was not an issue. The 5K system has never made a sound.

I have just updated the Multi to the latest Firmware version to no avail.

I also changed the Primo to MG60 and updated the MP and Assistant to 60Hz settings again with no difference in functionality

One note is that since updating to MH60 the pitch of the odd charging "crunch
sound has lifted in frequency.

Looking for some advice, please. This is very very odd behaviour indeed.

It feels to me like the MP is sending out bad info to the primo and making it consistently reboot.


jimbo asked
jimbo commented ·

1 Answer

Anti islanding


Has anyone added or installed anti island on the ac1 out of a multi/Quattro ?

The set up would be multi or Quattro AC coupled on the output 1 of the above inverters

No ac2 out connection

No grid or genny input on the input sides of the multis or Quattro's

The reason for the question is to keep a grid tie inverter on the out put working on grid outage




mikeb asked
mikeb edited ·

2 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

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