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multiplus in parallel

Multiplus in parallel leads to unbalanced currents

The setup is 3x Multiplus II 48/5000/70-50 in parallel mode single phase.
One Multiplus is from 2020. The other two are new from 2022.
AC cable lengths are equal and not oversized.
DC cable impedances are equal as possible between the units.

Unfortunately, the Muptiplus from 2020 draws a much higher current from the battery than the two new ones. The two new Multiplus currents are almost equal.

Test Inverting Test Charging
Nr. Serial number AC length [m] AC [mm²] DC [mm²] Firmware AC Limit [A] DC [A] DC [A]
1 HQ2219MY2DF 6 6 70 497 10 37 16
2 HQ2218AXMNP 6 6 70 497 10 38 18
3 HQ2037MH5DX 6 6 70 497 10 47 39

It seems that the "problem" is the old Multiplus from 2020. I think there were design changes on the PCB. PCB dimensions have changed. And the new ones show an unpopulated terminal block. (see pictures)

I bought the old and new MP at different shops.
I am not sure who can give support.

Can someone from Victron check (Serial numbers) if the Multiplus can work together?




pripp asked
nickdb commented ·

3 Answers

Parallel Multiplus configuration oddities

I have encountered a couple of odd unexpected issues during configuration of my two Multiplus' in parallel. System as described in earlier post.

I started by running VictronConnect and used that to update both inverters firmware to 5.01.

I then used VE.BUS System Configurator as per the Victron professional video to configure the inverters as a parallel pair, then used it to launch VEConfigure for each inverter. Two issues were encountered:

1) As per the Victron video I configured the first inverter and saved the configuration. I then tried to load this configuration and use it to setup the second inverter. This failed due to an issue setting the grid-id and it asked me for a grid password to continue. I guess this is either a bug or at least a special case if the grid code has never been set? I therefore backed out and manually duplicated the configuration on the second inverter.

2) During ESS wizard setup on the second, it failed to ask me to set the aspects such as restart offset or dynamic cut off values. I have run through duplicating the configuration for both inverters a couple of times now and both times it failed to ask me for these values on the second inverter. This seems odd - did I miss a step or setting or something, or is this normal for a parallel system?

ESS summaries for each inverter are posted below - odd large difference in the "size" of assistants too?:

Appreciate if someone can shed some light on the second issue in particular.

Thanks, Paul.



Paul Beskeen asked
Paul Beskeen commented ·

1 Answer

UPS design with Victron

I had Victron for short time, but then was forced to dismantle the units and replace with other system. There is no Victron support in my country and also for this reasons installers does not want to install Victron. As my current system is significantly underperforming (but reliable) I'm searching to have again power that is closer to my needs, but with reliability of current solution.

Maybe someone able will be able to help. I would like to build UPS like install with battery, ideally charged by solar cells. There is cca 8kWp on the roof, battery I would like to have cca 10kWh and maybe also with generator. I need 3phase 240V minimum 5kW per phase.

Known prolems with Victron units:

1. Random shut down with "unknown error" message and also shut down all other units

2. By shutdown grid is disconnected

3. Long transfer times when grid fails causing shutdowns

4. Discharging battery under minimal SOC

5. Extra loud (mainly during night when charging batteries depleted by point2) on full power

I heard that Victrons are used on boats in large scale. How it is done that unknown error does not power down whole ship.

What I had was 3x 5kVA multiplus, BYD battery, 2x MPPT charger, very powerful but not reliable

What I have now is GoodWe 10kW + Pylontech, very reliable, but greatly underpowered and no scaling possible

peter79 asked
Matthew Walsh answered ·

2 Answers

Can 2 multiplus 2k be in parallel and accept 240 if in charger only mode?

I want to be able to charge from 240 generator but have two multis in parallel for 4000k output. if in charger only mode will the problem of the parallel output be removed.

anotheroffgrid asked
Kevin Windrem commented ·

1 Answer

Modbus TCP Parallel System "Per Quattro" Information

I have a Parallel System composed by 3 Quattro's and a Cerbo GX. I cannot find a way to read the input and output current from each Quattro device via Modbus TCP, meaning I can only read the total current. I want to read the output current of each Quattro to insure their functionality. Is that possible in a Parallel system?

Thank you

hackerp asked
shaneyake answered ·

2 Answers

Miltiplus 5000/48 qui ne s allume plus

Bonjour, j ai un multiplus 5000/48 qui ne s'allume plus.

Il s'est eteint plusieurs fois suite à la décharge de mes batteries. Depuis, il refuse de s'allumer.. quand je bascule le bouton sur On toute les led s'allument, puis tout se coupe directement. Est-ce un relais qui a grillé du fait qu il s est allumé et éteint plusieurs fois de suite? Merci d'avance

morganegeeroms asked
myshopsolaire answered ·

1 Answer

Parallel Multiplus II installation and config

Due to lack of UK G99 certification I have had to swap out the originally supplied and installed 10kv Multiplus II for two 5kv units - which will need to be connected in parallel. I would like to to verify that my game plan for the conversion looks plausible. This system is designed for time shifting electricity, so its currently batteries only, no solar. The Multiplus IIs are 48/5000/70-50 units with very similar recent serial number/dates.

The DC side of the system consists of 6x Pylontech US5000s connected to a Lynx Distributor. These are split into three sets of two batteries each connected via a Pylontech long cable set to the Lynx and 125A fuses. The DC output from the Lynx to each Multiplus II is via duplicate sets of equal length 70mm2 cables. The positive connections are each made via a Marsen 200A fused isolator. Neutrals are directly connected.

The existing AC In and AC Out cabling is 10mm2 60A rated cables. The plan here is to connect each of these cables to a small consumer unit, one for AC In and one for AC Out. These will each hold 2x 32A MCBs and connect to the Multiplus IIs via equal lengths of 4mm2 twin and earth. Cable length for 10mm2 cabling is about 5 meters and for the 4mm2 will be about 80cm.

Hopefully this wiring setup will satisfy the requirements for equal length/resistance AC and DC connections, and individually fused AC connections. I would expect to cut the twin and earth to mm level precision - would that likely provide acceptable tolerance? Should I extend the length or, given such a short length, use 2.5mm2?

I'm expecting that I can config the system before I finally connect A/C side (its a parallel not 3 phase system). Also is it vital to have the BMS CAN BUS connected direct to inverter, or can that be left on the disconnected CerboGX during initial config?

Somewhat confusingly there seem to be several approaches to configuring the parallel system - VictronConnect, VE.Bus Quick Configure or VE.Bus System Configurator. I will need to update fw, install the ESS assistant and config each inverter separately. VictronConnect doesn't seem fully featured enough yet - so probably take the QuickConfigure/VEConfigure route...

I'm expecting that VEConfigure "AC input current limit", "charge current" and any other current defns will be half the required totals. Any other settings that should I be wary of for a parallel system? I also expect that ESS/battery settings done via CerboGX will not require halving.

Appreciate any comments/suggestions.


Paul Beskeen asked
Paul Beskeen commented ·

2 Answers

Grid Setpoint not tracking very well when running Parallel Multiplus

Started with a single MultiPlus-II 48/5000/70-48 and would maintain fairly well desired grid draw of about 50W with a steady load.

I now have two unit's in parallel, build dates are within about a week of each other (2022) and running 497 firmware.

Overall it seems to work and is stable apart from the grid setpoint tracking. With it set to 10W it will vary between 50-100W when the general draw is about 1000W. With a 4000W draw it will bounce around between 100-300W and so on with higher loads.

Are the unit's fighting each other to balance the load?

  • Running in ESS mode,
  • 6 x Pylon 3k Batteries
  • Smartsolar MPPT VE.Can 150/82 rev2
  • ET112 Grid Energy Meter before consumer unit
  • 240V single phase.
  • AC input is 20A MCB via 2.5mm2 cable to each inverter
  • AC Out 1 on both units connected together but not used which leads to an emergency outlet.
  • AC Out 2 are not connected at-all
  • DC side is 70mm2 cable, identical lengths.

mezo asked
rata1 edited ·

6 Answers

ESS (mode 3) - separat control-register for parallel configuration

Hello everyone,

I am using an ESS system in „mode 3“-configuration. The installation and control via Modbus TCP is principially working, but there is an open question regarding the usage of parallel configurations / several inverters on one phase.

From my point of view there are only 3 registers / values - one per phase - in the register-list to control the operating-point of the MP-II inverters. Is there a possibility to set the values independently for multiple devices on one phase or is the sum always splitted automatically?

The efficiency of the MP-II varies widely on the usage and especially in low-load situations it would be very useful to only use one inverter. In ESS (mode 1) the system does it automatically, but in ESS (mode 3) there seems to be a lack of control-registers to achieve this goal.

Has anyone an idea how to realize this functionality? Is it possible to configure the second set of inverters as a seperate ESS (with therefore own modbus-registers)? Can separate ESS exist in parallel and be controlled by the same cerbo, shunt, etc. and use the same battery system? Does it help to configure the MP-IIs to a separate 3-phase input group?

bbmz asked
Kevin Windrem answered ·

1 Answer

2 mutiplus et 2 pylontech us 3000 ne démarrent pas
excusez moi si le sujet a déjà été traité plusieurs fois, mais j'ai une faible connectivité internet dans mon île. J'ai donc deux multiplus : un en maître et l'autre en esclave. Je suis en mode ESS sur des batteries Crown de 6v 290ah;et j'ai acheté récemment 2 batteries pylontec us3000. Je n'arrive pas à les faire démarrer. Je soupçonne que le niveau de la batterie est trop faible pour me permettre de les démarrer... En effet, lorsque je les allume : les voyants SOC n'apparaissent pas, seul le voyant du mode RUN fonctionne. Dès que j'allume le multiplus, je passe directement en mode "alarme" avec un voyant rouge et je n'ai plus d'alimentation, même pas pour le CGX.
Que faire ?


ramassamy asked
Thierry Cortassa (Victron Energy Staff) answered ·

2 Answers

High Current Charging with 2 x Multiplus II in Parallel, ET112 and ESS during Offpeak Rate


I'm just about to place an order for 2 x Multiplus II 48v/5000w, 1 x ET112 meter and 1 x Cerbo GX and just need to make sure this is all going to work as planned.

I've been looking through the documentation and forums for several months. From what I've read it looks like it should work but I just wanted to double check / get some assurance that I've not missed something.

I have a cheap overnight rate on Octopus Go, 7.5p/kWh as opposed to 35.05p/kWh during the daytime. We've programmed out Air Source Heat Pump to charge during the cheaper rate and during an excess solar production from the 4kw SMA Sunny Boy.

I want to be able to charge 2 sets of 48v 280Ah LifePo4 Batteries connected in parallel at the terminals only (not between each cell) and managed by a couple of Batrium Cellmate K9's to keep them balanced.

As my cheap rate window is only 4 hours and my safe battery capacity (80%) I'm limited in how many kWh I can put back in the batteries during those 4 hours - 13.44kWh per charger, hence 2 chargers. (2 x 70A)


Will the above setup in ESS mode, allow all the loads in the house to be powered by the Multiplus's and Sunnyboy whilst not exporting anything to the grid, and then charge the batteries back to 90% on the cheap rate electricity ?

or would I be better of with a Quattro 10kw which can charge at 140A native ?

Best regards


simat asked
Paul Beskeen commented ·

1 Answer

Max generator input with MultiPlus 48/1200/13-16?

I only get 1000W from my generator when it's charging my bank via two MultiPlus 48/1200 units connected in parallel. Is that the limit of the units or have I got something set up wrong?

Changing the generator curretn limit (either up or down) does nothing! I don't get it - please help!

mark-hicks asked
mark-hicks commented ·

2 Answers

AC grounding parallel inverters

When your using two inverters in parallel how do you ground the AC. Do you connect each inverters AC ground out terminal with a wire or grounding strap to separate ground rods? The same ground rod? Were you connect one inverters ground to the other inverters ground and that inverters ground to the grounding rod. Thanks

justint asked
sharpener answered ·

1 Answer

Romex Question

I'm putting two Victron Multiples in parallel. I ordered some 6/2 Romex. Both wires run through a in wall main breaker with each hot going through one pole of a 2-pole 50 amp cfgi fuse. I just realized since the wires are Romex if I strip the outer insulation off in the box the wires may touch. Should I get 6/2 with a shelthed ground cable or use individual conductors so the 2 ground wires don't touch. Not that it inherently matters if they touches their ground wires. I just wanted to be safe. The wires will terminate in the sub panel on duel lugs. Thanks in advance for your help.

justint asked

0 Answers

Multiple issue with parallel (2) Multis on PylonTech battery system.
  1. [image]

    I had a single multi system working fine connected to my 20kwhs of PylonTech batteries. There wasn’t enough off peak grid available to recharge them from 10% to 100% over night (4hours) so I’ve installed a second Multi. I had multiple error messages last night as I tried to get everything to talk to each other and eventually managed to get it to schedule charge at 00:30. It drew 140amps which put one of my cables up to 102°c so I knocked the input ac amps back to 30amps and this reduced the DC amps to 100amps and the cable temp went down to 60°c, there was no fire risk but do need to look at the connections and / or cable size (25mm). The system recharged the batteries to 100% last night and started up this morning but the returned a #3 error, not all devices… found in the system.…and the. A low battery alarm.The system is saying the multi is not connected.
    I’ve done a hard reset on the system, even powering down the batteries and it started up with the Master showing the inverting led and the slave flashing the two lights which I presume means it’s working in slave mode but with no output to the AC out 1 which my heat pump is connected onto.
  2. I have read and watched the advanced videos on parallel systems and I did set up the master and slave via VEBus quick setup although I presumed there was only a need for one ESS assistant on the master.
  3. Any help would be appreciate, thanks.

Richard Weir asked
marekp commented ·

12 Answers


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