split phase Image

split phase

2 x Multiplus 2 in 2-phase ESS configuration on 230V IT (3-Phase Delta Norway)


I know that 3-Phase Delta is not supported. But what about using 2 inverters in a 2-phase configuration with 120 degrees shift? The goal is to be able to feed in more than the max 16A on a single phase limitation we have here in Norway, and still be able to control everything from one single Cerbo. I have no need for a real 3-phase network on the back side of the Multis. Some single phase critical load on one of them is basically enough. The second Multi should only act as a grid-tie inverter on a different phase to even out the power between the phases.

I got this drawing from a Norwegian Victron distributor. I assume it comes from Victron. I understood that this was somehow tested, and it works. There were some instabilities in the voltage on large load variations between L1 and L3, but except from that it worked. This setup may work in an non-ESS environment, since you can disable the N-PE ground relay. In ESS-mode you cannot disable the relay, and you will short L2 and L3 to PE on the output. The picture also states that "Ground/PE must not be joined"


So what if we modify the above slightly to something like this:


It is possible that the phase rotation will be wrong on the second unit. I'm not sure, but if we assume this is ok, this would allow ESS and feedback. In case of a grid failure, it will look like this:


The internal relays will disconnect the inputs. The ground relay will kick in and join N and PE. Since we here have a common phase for N (the L3), this will not short out anything. It will create 2 separate single phase TN networks on the output. As long as you don't connect any load between the 2 inverters I cannot see that that is more problematic than running one single unit, which works fine.

Can anyone here confirm if above solution will work or not?


oet asked
gerardg answered ·

3 Answers

Do I need MK3-USB interface when using Victron Connect app??

Hi Victron Community,

I already have one Multiplus II 5000 connected on phase L1 with a Cerbo GX and a 28 kWh DIY storage installed and want to add now one additional Multiplus II to my setup.

The new MP2 will be connected to L2 in my home.

To configure the system I can use the MK3-USB Interface cable, which I currently not have.

Configuring my first MPII I used the remote config feature via VRM portal.



I read that this can now be done also via Victron Connect app. But on the Video also the MK3-USB interface is shown, which is connected to a laptop. What sense makes it connecting the 2 MPII in serial with the MK3-USB interface to a laptop when I want to set up the system via the Victron Connect app from my mobile device? It was not shown under this link, what I should do with the laptop?

Do I need this MK3-USB interface cable for that?

Thanks in advance


jense asked
jense commented ·

1 Answer

quattro 240V with autotransformer neutral grounding question

In the Victron Schematic AT-1 split phase 240V to 120V-240V with Quattro 240V, How is the neutral of the autotransformer grounded when the Quattro has accepted the shore power or generator AC input, closed its input relays, and opened the grounding relay in the autotransformer via the GND relay control wiring?

It seems to me that it should be grounded or the fault current caused by a short circuit from one of the 120VAC lines to ground would not have a path to neutral to trip a circuit breaker.

ewbcvec asked
mvas edited ·

1 Answer

Dual Phase 120 on three phase + 0 grid connection (NL)

Hi everyone,

I've been receiving conflicting information regarding the possibility of a dual phase setup on a three phase connection in my home (netherlands). Unfortanately my contacts are of no help so I'm trying here in the community.

Reason being that I run a three phase victron setup with 3x multiplus II (230v 10kva) + Cerbo GX + lynx smart bms + 2x MPPT multi RS + victron smart batteries. But 1 of the multis is in RMA, rendering the system useless. Normally the whole house runs off the victron setup however currently I enabled the bypass switch in my house meaning the whole house runs of the Grid directly.

I have reconfigured the system to run 1 Multiplus II in single phase mode on L1, the other working multiplus II is on L2 but is disconnected. L3 multiplus II is missing due to RMA.

The AC out of any of the remaining Multis are not connected to anything since the load breakers are switched off and the rotary load switch breaker (Hager HIM402 HAG OMSCHAKELAAR 4P 20A MOD.M1) is switched to the grid option.

Here comes my problem. I have 15kwp of solar on the roof, and a 25A grid breaker per phase. This means that i can push around 5750W (+ loads but due to lack of grid meter that is not measureable) out of the single Multi thats running now. In combination with 30kwh this means that on a 80kwh production day or a day where the peak is not consistent due to scattered clouds its just bearely able to push all the PV out without hitting a 100% battery limit. But on days where its just blue skies it will throttle the PV when the batteries are full.

Not even to mention that that single multi is doing 6000W continious for 14 to 24 hours a day. Running at a lower efficiency and more noise and unneccesarily loading the battery bank.

The solution would be to run the 2 remaining Multis, with the multis on L1 and L2 in dual phase 120 mode. Am I correct to assume that what I want can be acomplished by configuring the 2 multis as below? What options for L2 would have to be selected?


Theres obvious reasons why you would not want to design your system like this, like drifting away from L3 when the breaker for L1/L2 for some reason trips. Which could result in damaged 3 phase equipment. Aswell as if breaker for L3 pops the three phase devices could be damaged aswell.

But in my case, there will be no consumers on the Multis, they will only be used to deliver the PV back to the grid.

Am I correct in assuming that what I want to achieve is indeed possible, and that its achieveable by the bus configuration in the attached image?

Any other reasons why in my case it would not be recommended to do?

Thank you for your time!

Marco Nijholt asked
larsea-dk commented ·

1 Answer

RV usage flaw: Split phase Multiplus can't charge low batteries on 30A shore

I seem to have encountered a major limitation when using two Multiplus units in split phase configuration while supporting both 50A and 30A shore power. It may even be a bug.

I have two 24/3000/70-50 120V (USA) Multiplus units in split phase configuration in an RV. In this configuration I'm able to power both 120V and 240V devices successfully. I have a 50A (split phase) shore power inlet but can also use a 30A (single phase) to 50A adapter if needed. I can begin to charge my batteries with both 50A and 30A shore power -- unless the batteries are too low (huh?? Read on to learn why!).

This setup works great most of the time. There are some problems when using 30A shore power. When on 30A shore power the typical 30A to 50A shore power adapter is wired such that it sends the same 120V phase to both Multiplus units. This results in the second Multiplus detecting that the phase of the power of receives is not the expected 180 degree out of phase. Therefore the second Multiplus rejects the power and only operates in inverting mode, powered from the batteries.

I've encountered two problems/flaws that stem from the above, both of which I believe could theoretically be resolved with software/firmware fixes.

Issue #1:

This one isn't as bad of an issue but it's annoying and is the origin of the major flaw detailed below in issue #2. The issue: I can never run my Multiplus units in 'charge only' mode when on 30A shore power. I get errors if I try. Ideally the second Multiplus would either act as if this was a parallel setup and charge the batteries or simply sleep and let the first Multiplus operate in 'charge only' mode. I am forced to run in inverting+charging mode.

Issue #2 (the bad one):

As noted in Issue #1 above the second Multiplus operates in inverting mode powered by the batteries when on 30A shore power. What happens if your batteries run out and then you plug in to 30A shore power? You can not initiate charging, that's what. This happened to me today when my batteries drained for the first time. I plugged into 30A shore power to charge them and... NOTHING! Errors!

Due to the low voltage in the battery bank the second Multiplus could not enter inverting mode (even though I don't even need it to invert right now). Because of this the first Multiplus refused to operate solo. Despite being plugged into power I was powerless and unable to charge my batteries.

Luckily I was at home and was able to hook up another charger to the bank which provided the voltage to get the second Multiplus up and running. Once I did this the first Multiplus began charging and the temporary charger was no longer needed. I essentially had to do this to 'jump-start' the Multiplus.

Some ideas to work around the issue:

  • Carry a spare charger or power source. Costs, takes up space, weight, annoying.
  • Auto-transformer. Costs, takes up space, weight, not always needed.
  • Raspberry Pi to swap out Multiplus configurations on-demand (e.g. to parallel temporarily for charging while on 30A)... Messy annoying solution.

I don't like any of those options. This is a software problem and I really don't want to spend more money for a worse solution.

Some questions:

  1. Is there a built-in way to solve this problem without additional hardware (e.g. a configuration setting I'm unaware of)? Is this considered a software BUG?
  2. Is there any way to get Victron to patch this problem? This isn't too odd of a use case.
  3. Anyideas of other simple solutions?

dustin asked
snoobler edited ·

1 Answer

Smart Phase controler

Do I need a smart phase controller with a Multi plus 2

louis becht asked
Kevin Windrem answered ·

1 Answer

Autotransformer voltage outputs are different

I am having an issue with the Autotransformer output voltages - 114V on L1 and 120V on L2 (with no load)

120V current is supplied by a Quattro 48V / 10000 / 140-100/100 to the 100A Autotransformer. I'm using the AT to provide a split-phase 120/240v supply to the 50A main break panel in my RV

I have wired the AT connections according to the diagram #3 shown on the system schematics page from the Victron website: (https://www.victronenergy.com/upload/documents/AT-3-split-phase-120V-to-120-240V-with-Quattro-120V.pdf)

The Ground Relay in the Quattro is set to ON and is correctly grounding the Neutral to earth.

Here are the voltages I read at the terminals:


The problem I have with this is that the voltage on L1 decreases a lot with load, and when occurs equipment will pull more current to compensate for the lower voltage.

Here is a pic of my RV control panel, showing the disparity in voltage between L1 and L2. Even though there are 2 air conditioners on Line2 it has only dropped 2 volts - Line1 dropped from 114v to 105v. This can't be good.


Questions: 1) - Is this method of wiring correct, and 2) what is causing the voltage discrepancy?


Aug-31: Editing this in an attempt to make the question visible again. I'm thinking of sending this AutoTransformer back to Victron as it is not performing to expectations. I have seen voltages as low as 96 volts on L1, at which point my UPS shuts down my computer, and various other circuits shut down. Not happy...

I'd appreciate a comment from anyone who has had experience with an AutoTransformer.


Pete MacLachlan asked
gutzpowers commented ·

6 Answers

VE.Bus system configuration L2 options

This question is about setting a second Multiplus 2 on phase L2 with dual phase 120 degree (European 230/400V grid).

Is there any explanation about the "options for L2 phase" fixed, floating and floating with return to original phase? Which setting is most appropriate?

I cannot find anything in the user manuals, instruction videos or this forum.



morres83 asked
thomas-pv answered ·

1 Answer

What is the Difference between 120V/230V Multiplus/Quattro?

I would like to install two multiplus or quattro units in parallel to get split phase 240V (120V line to neutral, 240V line to line. USA install). However, some units are labeled 120V, while others are labeled 230V. Does this impact which units can be used to produce the desired split phase 240V output?

Also, is it true that the 8kVA and up multis cannot be connected in parallel, while this limitation does not apply to any of the Quattros?

What are the largest two units that I could connect in parallel to achieve a 120V/240V?

awbower asked
snoobler edited ·

1 Answer

3-phase generator in delta for single phase 230V without neutral on Quattro input possible?

We have a 13,5KVA 3-phase Generator 230V/400V (Linz E1S11M B) but only need single phase 230V for the Quattro 5KVA 230V. We can only load the generator to 40% on one phase which is not enough to load the diesel appropriately.

So we thought about changing to the delta configuration on the generator side which also means losing the neutral conductor.

We have L-N 230V shore-power via a Isolation transformer on AC Input-2. All loads are on AC Output-1 with RCD and breakers.

Is this configuration possible?

member040 asked
member040 commented ·

1 Answer

On grid 8kW Split-Phase (230v UK) with storage + solar

New to Victron devices but I suspect they maybe just what I need for the following project:


AC connection: Split-Phase

Grid limits: Max 9kW inverter per phase with 8kW export limitation per phase.

Solar: 18kW

Storage: 48v 20kW

EPS backup

Remote access control (App)

Any advice on component selection + considerations for the above setup would be greatly appreciated.

Things currently on my mind:

Can Victron inverters work reliably in this mode?

Can a common battery be used?

Do Victron support any storage batteries with pre-defined settings, eg Pylontech?


50hz asked
matt1309 answered ·

9 Answers

Multiple Energy Meters on US 400A service (2 feeds)

I have a Dual Quattro 5k 120V USA split-phase configuration with EM530 energy meter and Cerbo GX. It works great! However, the house has two independent 200A feeds from the meter base, so I am only metering one of them. I’d like to feed excess solar into the other feed for the remainder of the house, but never ever export anything to the grid. Will adding a second EM530 on the other panel work if both are called Grid Meters (i.e., will they add up?) or will the Cerbo TX get confused?

rickc asked

0 Answers

Using AutoTransformer to create 120v/240v split phase from single phase 120v input

I have a use-case for the AutoTransformer that is different from what I see generally discussed. I want to use it in my RV to take in 120v 60 Hz from either my Onan Generator (2 separate 120v legs that are SAME phase) or the shore power inlet (30/15 Amp which are 120v 60Hz single phase). I have those 2 inputs going to an automatic transfer switch so whichever one is "on" will pass through to the AutoTransformer. I would like for the AutoTransformer to step up the voltage from 120v single phase to 120v/240v split phase. I will then pass that split phase into the input side of my dual inverters (one inverter for each 120v leg) so that when I have a single leg input, I still get both inverters charging instead of one side passing through voltage and the other rejecting the phase and inverting to make the "correct" phase.

So, my question is, how should this be wired up to the inverter. It has labeled "input" and "output" sides but the "input" side only has 240v Line and Neutral labeled connectors. The "output" side has 120v Line 1, Neutral, 120v Line 2 connectors.

My intuition tells me to disregard the input/output labeling and connect my source 120v power with:

source 120v Line > AutoTransformer "output" Neutral

source Neutral > AutoTransformer "output" 120v Line 1

Then my output would be the 240v wave form stepped up via transformer as measured between the "input" Neutral and "input 240v Line connectors. I would need to carry over the neutral from the other side to provide 120v/240v split phase.

It is this last part I am unsure of and need some guidance on.


Diagram attached of my planned whole system that hopefully makes clear what I am trying to achieve.


cookinwitdiesel asked
jjbond answered ·

4 Answers

L1/L2 probably swapped?

Hey everyone,

My question has been discussed several times, but as I am not the one who installed the Victron etc. and the electrician who did doesn't know Victron well either, I'd like to get your feedback so I can tell him what needs to be changed (he's coming back in a few days for some last things so a great chance to fix this).

What I wanted my installation to look like was the following:

  • L1 for "critical loads" using a Multiplus 2 48/5000, attached to the battery (Pylontech)
  • L2/L3 remain connected to the grid
  • EM24 for energy metering

The installation works fine, no problems.

However, the results I see in the pictures below doesn't seem right.

The "victron feed" image, on a high level, states I believe:

  • MPPT generates 3710 W
  • of which 3083 W are fed into the grid
  • the Multiplus routes 3200W on L1
  • while L1 consumes 506 W from and L3 26 W

I think AC Loads with the 3200 W is correct, but Grid with -3140W should be on L1 as that is the Multiplus connection, and not L2 which is connected directly to the Grid?

So L1 and L2 are swapped - maybe from grid to EM24 or EM24 to Multiplus?

The "victron consume" image states, I believe, that 311W + 113W = 424W are used directly from battery an MPPT for the critical loads, and 24W are on L3.

But if L1/L2 are actually swapped, then in a fixed setup I would actually see

  • 30W (not 4W) on L1 from the grid --> 30 W difference to AC loads, so maybe that's the Multiplus?
  • 4W (not 30W) on L2 - no idea where the 27W difference (31W-4W) on L2 AC Loads comes from though?





michaelanders asked
Alexandra commented ·

0 Answers

120v / 240v simultaneously with Multi+ Compact split phase config?

I am a home owner with a battery backup system I built for my home. The system provides a limited power source when grid power is not available. It uses a Victron MultiPlus Compact 12/2000/80-50 120v inverter/charger. It has a 400 Ah battery capacity and a small solar array. When used, it needs to be connected manually to the house system, I don’t use the automatic transfer function. It currently only provides a 120v output for the house circuits.

I would like to expand the system capability by adding another identical Victron inverter and configuring them as a split phase system to provide both 120v and 240v to the house breaker panel. I believe this is possible using a second MultiPlus Compact inverter. Appendix E in the inverter manual is my source. I’d like to verify that, in the split phase configuration, the outputs could be connected to a standard household breaker box and operate the same as the grid power. Each inverter 120v output would be connected to one of the ‘hot’ breaker legs and the common neutral would be connected to the breaker box neutral.

There is one 240v circuit for a water pump that I am trying to power (.37kW single phase).

Would this operate as I am expecting?

Thanks in advance for any help.

carlk asked
carlk commented ·

2 Answers

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