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Graydon asked

Running 4 Multipluses in split and parallel phases

I have a fourteen bank 24v/210Ah LFP batteries , totally about 75 kWh of power.

I have two 24/3000 Multiplus’s running in 120v split phase configuration.

This all connects to a subpanel that powers all of my home essentials (freezers, fridges, computers, network, cameras, pool, and AC).

In times of ample solar input, like days and days of it, I will switch my main panel over to my subpanel, and shut off the grid input. Thus running my whole home on solar, as long as the sun shines.

This has worked very well, with the exception of high current items like my dryer and oven. I could not run my dryer (5000W) on my current setup (2400W limit on each Multiplus), while running everything else. The oven will run, with lots of overload warnings.

I was thinking of some options to be able to run my whole house off Solar/batteries, on long stretches of sunny days. As well, our area (Ontario Canada) has instituted a very very cheap overnight charge rate of 2¢ per kWh. So, If I ran everything off battery/solar, I could charge up the batteries between 1pm and 7am at a ridiculously low rate.

Options I was considering

  • Upgrade to a 48v system, and run two 5000 to 8000W multiplus(s)/Quattros in split phase
  • Keep my current 24v configuration and run two Quattro 24/5000 in split phase
  • Add 2 more 24/3000 Multiplus(s) and add each to my current configuration. So, two in parallel, each running in split phase (4 Multiplus(s) 2p2s)

Option A:

It would be easy to convert my battery banks from 24 to 48 volts, by simply adding one copper bus bar to each bank. However, I am concerned about having four 12v batteries in series, and will the middle batteries always staying balanced. (I am looking at some third party 48v /4 battery equalizers).

Also, I would have to buy 2 more Multiplus(s)/Quattro’s in the 5000+ VA range, which are almost $4000 each or more.

If I were starting over, I would definitely run a 48v system.

Option B:

Staying with a 24-volt system is the easiest, but again, buying two 5000 VA Quattros is going to cost $9000

Option C:

Buying 2 more 24/3000VA Multiplus(s) is the most economic, as they would cost less than $3500 for both.

HOWVER, now I am running a system of four Multiplus(s) in parallel and series. Two Multiplus) in parallel give me 6000VA or 4.8 kW nominal power on each phase, which is more than enough for my needs.

A side benefit of having 4 Multiplus's, is that if one breakdowns, I have ample redundancy to go back to a simpler split phase system.


My question is: How reliable is running four Multiplus(s) this way? Victron advertises being able to run 6 units on each phase.

I am very VERY happy with the performance and reliability of my units at this time; they have never disappointed me to date, over 2 years. I am worried this new configuration may not run as smooth?

Multiplus-IIMultiPlus Quattro Inverter Chargermulti phase
2 |3000

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