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Is there a minimum power of the battery bank for a Victron Energy Multiplus inverter/charger?

Hello, I hope you are well. I am Rahmouni Ayoub a PhD student engineer and I work on microgrid systems. One of our objectives is to realize a laboratory prototype that will contain a photovoltaic emulator that will produce a power of 3kWp connected to the AC bus via a photovoltaic inverter brand "Fronius", a group of batteries with an inverter charger "Victron energy" and other backup sources. According to the rule of the factor 1.0, the inverter charger must have a minimum power of 3kW because our photovoltaic source is 3kWp. but in our case since we use a photovoltaic emulator and even the load is a programmable load so we can simulate our day in some minutes. For this we don't need a battery capacity equal to the one used in a real model (that is to say we need a capacity of about 100ah maximum for our prototype). So my question is, is there a problem if I use a low capacity compared to the one used in real conditions with a 3kW inverter charger? (the capacity in real conditions is about 400Ah/24V).

Thank you very much!

ayoub-rahmouni asked
sharpener answered ·

1 Answer

Unstable Microgrid Multiplus II - Fronius


Multiplus II 48 5000, Cerbo, Fronius 501 @ ACOut, no feed in,


Fronius: - set to MG50,

Multiplus II:

* programmable relay and general flag assistants are used to ignore AC In1 if SOC >50% not ignore if SOC <30%;

* PV inverter support at last position in assistant list.

Fronius is connected via WIFI to Cerbo and it looks as it should.


Cerbo is showing: Fronius 350W, AC Load 105W.

The issue is that the battery state changes from charging with 900W to discharging with 700W couple of times per second. BMS shows similar values.

In this stage ESS assistant is not an option.

Somebody has this issue before, is there a fix for it ?

popnic asked
Dave Rae commented ·

37 Answers

Micro-grid with MultiPlus II and Fronius Primo - causing flickering lights


We built a new single-phase installation recently with the following components:

  • MultiPlus II 48/5000
  • Cerbo GX
  • 4x Pylontech US2000C
  • PV inverter Fronius Primo 4.0

Grid is connected to MultiPlus AC in, all loads and the PV inverter are connected to AC out 1, like so:


Grid metering is done by the internal meter of the MultiPlus, Fronius is connected via ethernet (zero feed-in with ModBus via TCP).

Generally speaking, this setup works really great, now we're getting to the last 10% of optimization, and the current issue is the transition from grid-parallel to micro-grid, which causes the following:

  • Error 105 on Fronius (AC frequency too high) when switching off the connection to the grid (Fronius restarts/recovers quite quickly though)
  • Flickering lights at certain load constellations while operating on micro-grid (e.g. Fronius delivering 2.5 kW and loads around the same value (oven + small toaster)

The flickering can be described as brightness oscillation around 1-2 Hz, as if MultiPlus competed with Fronius for the voltage regulation. If useful, I can upload a video later.

Parameters are set as recommended by the documentation (MG50 on Fronius, Frequencies set in the ESS assistand according to https://www.victronenergy.com/live/ac_coupling:fronius). Native Fronius zero feed-in works fine also. The documentation mentions "Q5 How can I get the Fronius firmware that improves flickering?", but the Fronius is brand-new and all firmwares have been updated, so this shouldn't be the point.

Any ideas and help is much appreciated :-)


ips-ad asked
Rob Duthie edited ·

2 Answers

Which battery technology is most suitable for use in microgrid systems ?

Hello, I hope everyone is well. From a literature search, I found that people are using lead acid batteries as an energy storage source. but from other battery researchers, they suggest using li-ion batteries for microgrid applications. so my question is what type of batteries are most used in microgrid applications?

ayoub-rahmouni asked
Alexandra answered ·

1 Answer

plc-controllable inverter (micro grid)

We want to dimension a PV + Batteries installation a little more complex than usual in order to be able to carry out microgrid tests in our installations, we are interested in the added value of being able to carry out different tests in our installations.

To do this, we would need an inverter with remote management capacity, we want to monitor the status and send remote orders to the inverter via a PLC/ IoT device in our energy management system to carry out operations such as selecting the supply source (grid, battery, panels), limiting the power of the panels, etc... all this under a criterion that sometimes may not be economically optimal but, as mentioned, we value from the point of view of microgrid testing.

which inverter allows me to control the parameters with a plc and what connections should I make, I suppose that the best protocol is modbus tcp, the power of the inverter charger should be around 50-60 kWp three-phase output.

Thank you very much

Translated with www.DeepL.com/Translator (free version)

alvaroitcl asked

0 Answers

Victron Multiplus 12/1200/50-16,230v - AC Grid feed-in based on Battery Voltage

I would like to be able to feed-in to the AC grid when the battery voltage exceeds a certain voltage (10.0V), the battery has an external charge source and the inverter will maintain this desired battery voltage by feeding the excess energy into the grid. Please advise on how to set this up. I have all the necessary protocol equipment such as the CerboGX modules, MK-USB3 cable, GX Touch, BMV etc but looking for advise on how to configure the inverter for the desired operation. Please advise.

solshare2022 asked

0 Answers

Moving load from grid to inverter when the load goes too high

I want to change my grid connection from 150A 3 phase to 80A 3 phase to save costs. The problem is I need to provision for load spikes that exceed the 80A supply and I do not have control over the loads (Commercial tenants). I am planning to add 3 x 15Kw Quatro inverters to the supply, but I want to know if there is a way to allow and control feedback from the battery bank / charge controllers to negate / mitigate load spikes when the loads reaches 70A or higher on a phase or more. So if a phase needs 100A, I want to supply 30A from the inverter / battery bank instead of causing the grid to trip.

Can this be done in ESS, MQQT or Modbus if I add a 3 phase CT meter to monitor the loads? How would one program this and what equipment is needed?

mcwidowmaker asked
Kevin Windrem answered ·

4 Answers

Grid Tied Inverter on existing Quattro Inverter


I have 2 Victron Quattro inverters of 15 kVA dc coupled with a 48 V Lead Acid Battery bank.

We wish to synchronize 3 x Huawei SUN2000-5KTL-L1 with the Victron system. The Victron system will act as grid and the Huawei inverters will be configured for net zero export. However from the response time of the net zero export, for a brief time of 5s, power is exported (as shown in figure).

Can someone please confirm if such a system will work without damaging the Victron inverter?



yashtir asked
Paul B answered ·

1 Answer

Fronius Primo 3.0-1 alternative?

Hi all,

I have an EasySolar 24/3000/70 (with batt, bms etc.) already installed and with some extra solar panels (3330 Wp) I'd like to have the possibility of a microgrid. Fronius Primo 3.0-1 with MG50 fw seemed to be a good choice AC coupled inverter for these extra panels (complies with the 1:1 rule). Unfortunaltely the Primo is no longer available. Now I'm looking for a good alternative AC coupled inverter, suitable for microgrid, for this 3kVA system. Any suggestions? Thanks in advance!

Dennis asked
Alexandra answered ·

1 Answer

Replace APS YC500I ?


I currently have two PV arrays at home:

- 6,7 kWc with Fronius Primo 6 kVA

- 1,2 kWc with two APS YC500I micro-inverters

I try to add AC-coupling ESS functionnalities with a Multiplus II 8 kVA + Pylontech US2000C batteries...

System works with Fronius (MG50 profile) but not with APS micro-inverters. APS micro-inverters are not injecting power correctly...

It seems that they are not compatible with micro-grid mode.

Do you have advice/recommendation if I decide to replace the APS micro inverters ? Enphase ? Other model ?


positron asked
positron answered ·

2 Answers

How to connect Multiplus II and Microinverters

My Setup:

12 x panels (a 400 Watt)

3 x Microinverter (Hoymiles HM-1500)

1 x DIY Lifepo4 battery (16 cells a 280ah)

I would like to buy 3 x Multiplus II 48/3000/35-32 and connect them to L1, L2 and L3. Using a current sensor I’d like to achieve zero feed in.

For the sake of simplicity lets just look a one phase:


So in my image this would be:

(A) connected to (B) : power grid and microinverter

(A) connected to (2) : power grid to ACin

(3) connected to (A) : ACout2 to power grid

So I have a direct connection between ACin and ACout2, no?

markus32 asked
marekp edited ·

2 Answers

Victron Multi + Fronius Primo Hybrid system!


I am having the Fronius AC Coupled at Multi's AC Out1, and trying to set all for Grid Feed-in limited to a given value.

Should it be the Fronius discovered on the Modbus TCP device list? for me is not there. Scanning not helps.


zsolt asked
anthony answered ·

1 Answer

AC Coupling - Microgrid Total Output Capability with Foronius

I am having a brain fart with a simple question and cannot find the answer anywhere. If I have a Multi 3000Va paired with a Fronius 3000Va unit connected on AC output 1, is the total theoretical output 3000Va or 6000Va?

flip-flops asked
flip-flops answered ·

2 Answers

Two fronius inverter connected to AC-OUT: 1.0 rule

Hi together,

I have two fronius Symo 15kVA with 36.5 kWp combined PV panels, currently connected at AC-IN, so they will be shutdown during grid outage.

In addition I have 3 Multiplus-II 3000 with 8 Pylontech US2000 48V and 4kWp via an MPPT-RS.

Everything is 3phase in my household (heat pump, oven, cooking, wallbox...).

If there is a long power outage (days to weeks) I'd like to have the possibility to rewire the fronius inverters to AC-OUT and reconfigure them to MG50 frequency shifting to also use the power that they generate.

Now my question: is it possible to use this configuration if I limit each fronius to max 4.5kW via Fronius Grid configuration? This should then be 2 x 4.5kW = 9kW distributed over 3 legs. So it should still match the factor 1.0 rule because there is never more then 3kW on AC-OUT on each of the Multiplus-II 3000.

Will frequency shifting still work in this configuration?

christoph-dunker asked

0 Answers

Question about MP2 with on-grid inverter

How to display a negative power out on the overview as this photo shows? I'd like to display the AC output power instead the AC loads, which as shown cant be negative.

Thanks a lot in advance.



Google LocalGuide asked
Google LocalGuide answered ·

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