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alaskannoob avatar image
alaskannoob asked

Two Multiplus II in parallel - generator wired into just one?

I have 2 x Multiplus II 48/8000s that I am planning on wiring in parallel to provide 240 out and charge the 48V battery bank.

I'd like to have my generator on auto-start to help provide power and charge the batteries as required. It has a 120V output cable, can I wire that into the AC-IN of a single Multiplus II or do I need to wire the generator into both units?

multiplus in parallel
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Hi @AlaskanNoob

I'll contact you by email about this.

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3 Answers
derrick thomas avatar image
derrick thomas answered ·

If parallel units then it must be connected to both. If split phase then you can connect it to one unit and be sure to deselect "switch as group" when configuring the multi's

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alaskannoob avatar image alaskannoob commented ·

Okay, thank you so much for that info.

I do have a 240V out cable for the generator but it only has four lines on it. L1, L2, N, and G. Do I need a different cable to wire it up to two Multiplus?

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marekp avatar image
marekp answered ·
Unless this changed recently, the Multiplus-II 48/8000 model cannot be used in parallel configuration.
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alaskannoob avatar image alaskannoob commented ·

I haven't seen any documentation that suggests 2 x 48/8000 cannot be used in parallel. And they were purchased by the dealer for this purpose.

The manual doesn't suggest some models of Multiplus II can parallel while others cannot: https://www.victronenergy.com/upload/documents/MultiPlus-II_230V/32424-MultiPlus-II___Quattro-II_120V-230V-pdf-en.pdf

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sharpener avatar image
sharpener answered ·

@Guy Stewart (Victron Community Manager) shouldn't this limitation be spelled out at 4.4.7 in the manual @AlaskanNoob links to?

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marekp avatar image marekp commented ·

@sharpener

I would point to the page 32 of said document where one can get false notion that this model can be connected in parallel.

Read the description of the pointer "E"

2x RJ45 VE-BUS connector for remote control and/or parallel / three-phase operation

screen-shot-2023-02-21-at-94135-pm.pngSo is this an error or MP-II models 8k, 10k and 15k can be connected in parallel?


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alaskannoob avatar image alaskannoob commented ·

Just saw on the data sheet that it specifies 8Kva (and two other Multiplus II versions) don't support parallel. I really wish the manual had specified that. And that our Victron dealer had been aware of it.


When discussing what equipment to buy for our off grid installation, he suggested that two 8000s could be put in parallel and that we could use the Victron autotransformer on the other side. So we bought all three components, the 2 x MPII 48/8000 and the Autotransformer (not to mention the Lynx Distributor and the 2 x SmartSolar 450/200 MPPTs). The dealer wrote:

"You set it for 60 hz and 240v is standard. What’s different is it has no neural or 120 output. Hence the Autotransformer. You can stack parallel victron gear. If you wanted 2 8000s that would not be an issue. It would be 66A into the 100A auto transformer."

So we said, "[Name], can you add another Multiplus II like the other onto the quote so we have the option to run single phase 240V at double the amps (70-ish)?" and he responded "Can do and we will add a second 8000."

I suppose the next step is to contact the dealer and hopefully ship these two 48/8000s back to the lower 48 from Alaska (not cheap) and get 4 x 48/5000. But first, @Guy Stewart (Victron Community Manager) could you confirm that we can't parallel two 48/8000 models? I'm hoping it's just an old data sheet document and that page 32 of the manual (which does indicate that 8K-15K models can be run in parallel) is correct and informed my dealer's understanding.

It just seems odd that we can parallel up to six Multiplus II 48/5000 models, but not 2 x 48/8000 models. Hopefully this data sheet just hasn't been updated?

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alaskannoob avatar image alaskannoob alaskannoob commented ·

If it is the case that the data sheet is correct and the manual page 32 is in error, this message may not be getting out to all dealers.

This dealer advertises the MP II 48/8000 on their page and states for the 3K-10K versions:

"Virtually unlimited power thanks to parallel and three phase operation- Up to 6 Multis can operate in parallel to achieve higher power output. Six 48/5000/70 units, for example, will provide 25 kW / 30 kVA output power with 420 Amps charging capacity. In addition to parallel connection, three units of the same model can be configured for three phase output. But that’s not all: up to 6 sets of three units can be parallel connected for a 75 kW / 90 kVA inverter and more than 1200 Amps charging capacity."

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alaskannoob avatar image alaskannoob alaskannoob commented ·
I'll go ahead and contact the dealer today and see what they say.
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alaskannoob avatar image alaskannoob alaskannoob commented ·

I contacted the dealer who had previously told me the 48/8000s would work in parallel and he said he's looking into it. I should have something to report soon.

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alaskannoob avatar image alaskannoob alaskannoob commented ·

Unfortunately, the dealer who erroneously told us the two 48/8000 units would operate in parallel and which led to our decision to purchase them, has stated that Victron is unwilling to cover the cost of us shipping the units back to him. He said "I dont see any requirement for me to pay the shipping to return these or to return them in general."


Since Victron has admitted their manual was in error regarding parallel operations, I was hoping the company or the Dealer would cover the shipping costs. Since we already paid to ship the units to us, I don't believe we should have to again pay for shipping them back given that a Dealer and a manual were both in error.

I have sent an email to Victron's Regional Manager for North America in the hope that he/she can assist although I didn't get an email from that Victron form after I submitted, and there is some discussion of whether it actually does anything. I guess we'll see.

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alaskannoob avatar image alaskannoob alaskannoob commented ·

I should have updated this thread, Victron and the dealer sent me a Quattro 15K at no charge, and I sent them back one of our Multiplus II 8000s.


The Quattro has been supplying power for our off grid property.

I did hear a rumor recently that with a software update, the Multiplus II 48/8000 might now be able to be paralleled. Does anybody know if there is any truth to this rumor?

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nickdb avatar image nickdb ♦♦ alaskannoob commented ·

Nope, not yet. And your dealer should have known this at the time. It was listed further down the doc specs but not everyone noticed. Docs have been updated to be more obvious:

Virtually unlimited power thanks to parallel (not for the 8k, 10k and 15k models)

I may be mistaken, but the focus was first achieving certification for the units, last year we saw them approved in our region.

The quattro was the right choice, 4 units in parallel is a pain in the backside, imo.


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alaskannoob avatar image alaskannoob nickdb ♦♦ commented ·

Why do you think paralleling them is a pain? I've heard that from one other person with experience as well who said it's better to have one unit.


The Quattro has been doing great and Victron was excellent in swapping it for our 48/8000. The only downsides have been the electrical load the Quattro takes in idle is pretty high and it was a challenge for the wife and me to install due to its weight. But it works great so far.

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alaskannoob avatar image alaskannoob alaskannoob commented ·

Jan Klumpenaar from Victron Sales just informed me that the Multiplus II 48/8000 cannot operate in parallel, but that it will be able to in the future although there is no timeline for that.

I will contact the dealer about exchanging the two units I purchased for a different solution.


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