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oxy avatar image
oxy asked

Increasing "old" MultiPlus 5000 setup to 10000 VA (parallel, serial?)

Hello,

We have a MultiPlus 48/5000/70 battery-only off-grid solar setup. We recently added an additional solar array (increased from 5kW to 10kW), and now need to extend the max AC power from 5000 to 10000 VA.

I have been using and adding various Victron components during the years and thought that with time, when we add more solar panels, I'll be able to utilise the so-much advertised "Virtually unlimited power thanks to parallel operation" quote. To my despair, I just got reply from the dealer that my MultiPlus "is too old" and can't work in parallel with the units that are sold Today!? Is this true? How can it be?

Our MultiPlus has the following version sticker on the processor: 1959143.VFD

  • Isn't it possible to upgrade the firmware to work in parallel with the currently sold MultiPlus?
  • Isn't it possible to buy a MultiPlus with the compatible "old" firmware to my owned MultiPlus?
  • If parallel is impossible, are there any other alternatives, like connecting them in serial? I.e. feeding AC-Out of the "old" MultiPlus to the "new" MultiPlus AC-In (with charger disabled) and expect that PowerAssist would kick-in when AC-in limit is reached? It would be set to MultiPlus max power. This way the "old" MultiPlus would take most of the load, while the new one would kick-in only when more than 5000 VA are needed.

If nothing of the above is possible, what would you suggest? One of the reasons I went with Victron years back was because of that "Virtually unlimited power thanks to parallel operation" quote. Was it just a marketing trick which only works in one corner case when you buy all the equipment at the same time, and there is no backward compatibility designed-in?

Please help.

MultiPlus Quattro Inverter Chargerbattery chargingpowerassistac coupling
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kai avatar image kai ♦ commented ·

If you're only needing additional AC out, then an additional inverter would also solve that need, unless you're needing >5kVA coming out of a single socket.

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alan avatar image alan commented ·

This seems to support the serial theory should work

https://community.victronenergy.com/questions/18872/adding-extra-mppt-and-inverter-to-easysolar-243000.html

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oxy avatar image
oxy answered ·

p.s. Worst case scenario, if there's no way to make my "old" MultiPlus work in parallel, would it be possible to add a PV-inverter to the system, as described in the link below?

https://www.victronenergy.com/live/ac_coupling:start

It would be enough to have 5000 VA from batteries and potentially +5000 VA from PV-inverter during the sunny days, but does 1959143.VFD firmware supports that? At least right now, it doesn't have the "PV Inverter Support Assistant" (and no assistants altogether). The above link says "Other options, all deprecated, are:"

3. Use the Inverter period time settings on the Virtual switch tab.

Is there any page describing how it is configured?

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Paul B avatar image
Paul B answered ·

As a option why dont you replace the processor board and thus upgrade that unit to the latest version 26 series processor, the rest of the unit should be comparable.


you would then add another unit in Parallel and you have 10,000VA

you could then use Grid Tie OR MPPT


for your existing you can add MPPT as much as you want as these are independent and dont requires assistants


BEST option upgrade the main board AND add the secound unit.


If you speak nicely to the Victron distributer in your area, you may find that the board is not that expensive plus they MAY buy the old board back off you as a spare for someone else you never know unless you ask, and yes it maybe a punt as I dont know the age of your orginal unit

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oxy avatar image oxy commented ·

Thank you for your suggestion, Have you had good experience with this approach? Distributor and Victron know my issue, but did not mention this option. Does the hardware of the old 19 version CPU MultiPlus would be able to work with the new CPU version? Do you know if it is possible to do this in-house or does the unit needs to be shipped?

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Paul B avatar image Paul B oxy commented ·

Its not recommended, but its something you can try if its NOT overly expensive, they wont recommend it because if it does not work they are on the hook.

but if you take the punt then and if it does not work then you ware it

Another option is to buy a new unit and then swap the board over for the test, you are unlikley to damage the board it will eighter work or not.

its easy to do

take the front blue cover off

then board is right in front of you unscrew a few screws unplug a few plugs and replace. So yes it can be done on site

Again it should work (I have done it once before, maybe I was just lucky) its not something thats done all the time as there is usually no need.

BUT be warned there is NO guarantee that it will work

another approach is to find a secound hand board out of a old inverter that has a blown or damaged rear end but a good front board and downgrade the new unit for testing

B carefull that you get the same VOLTAGE and pass through amps (it has to be the same model and voltage and charge etc units main board)

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oxy avatar image oxy Paul B commented ·

Yes, looks like Transfer Amps is one parameter that got increased in new models from 50A to 100A, hence the firmware version’s third and fourth numbers differ from my current unit. The first and second numbers differ due to CPU, but as @Rainbow Solar pointed out, in that official document it gives example where parallel operation is possible even with first two different firmware numbers (old and new CPU).

I do see in another firmware history document that there was a 50A model with the new CPU manufactured for an unknown period of time, and can find some listings in some online shops (they look outdated though). If to trust that official document, this new CPU but “old” 50A transfer switch MultiPlus would parallel up with my old CPU “old” 50A transfer switch model, but I don’t know what to believe any more - official docs or strict forum posts that say both units must be “identical”.

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Paul B avatar image Paul B oxy commented ·

As I said its a give it a go,

If you put the new board in then it will think its got a 100 amp relay even though its only a 50 amp


so just make sure you keep the incoming amps down to 50 max on that unit

the other new unit will have a 100 amp relay in it.

This is all your call and its only a work around suggestion

I would order a new 5000 unit and at the same time order a replacement spare board for that new unit,

Then you have two boards the same with the same 26 series processors for connecting. the old unit

Anyway I cant strees enough that this is not recommended, its a posable help out for you if it works.

keep in mind that I do not work for victron and therefor, if you try this you cant , Blame them for any issues if they occur. OK

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Rainbow Solar avatar image
Rainbow Solar answered ·

From this document, it seems you can connect your Multiplus to the old Victron Multiplus with 26 and 27 processors while using the same firmware. https://www.victronenergy.com/upload/documents/manual-VE.Bus-firmware-versions-explained-EN.pdf

I do not think your Multiplus will work with the latest Multipluses which may be what your dealer has in stock. You can get old stock of the old Multiplus from various sources including online e-commerce stores.

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oxy avatar image oxy commented ·

After reading all the posts about parallel issues in this forum, I have a feeling that this document is very outdated. In all the forum posts the last word they say is that both parallel units must be “identical”, while this document states it’s fine to mix old & new CPUs as long as the firmware (last three digits) match. Go figure..


BTW, why do you call 26/27 MultiPluses “old”? As I understand that’s the new CPU, while mine “19” is the old one.


p.s. If you happen to know of a seller who may stock old MultiPlus in EU, please share. All I see are “new listings”...

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oxy avatar image
oxy answered ·

@Guy Stewart (Victron Energy Staff) I would appreciate if you could chime in. I read your other posts and your experience would help.


If it turns out there’s no way to parallel the 19 version MultiPlus with Today’s MultiPluses in stock, would it be possible to feed the old one’s AC OUT to the AC IN of the new one, set Input Current Limit to the nameplate amps of the old MultiPlus, disable charger and expect PowerAssist of the new one to add those +5kVA when loads get above 5kVA? This way old MultiPlus would be taking most the loads while the new one would sync its waveform and PowerAssist when there’s a need. If that’s impossible, would be great to know why - how MultiPlus output is different from analogous powered generator or grid. I believe it should even show up in ColorControl GX nicely in the red ac input box, so you could always see how much is first and second inverter inverting. Would there be any settings to be aware of (like Dynamic Current Limiter).

Also, maybe there’s a better combination to achieve the above? I have not yet bought the new MultiPlus, so there are choices. Maybe it’s better two MultiPlus in parallel, or Quattro 10000 and feed the resulting 10kVA to the AC IN of the old MultiPlus 5kVA?

Big thank you in advance!!

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alan avatar image
alan answered ·

There shouldn’t be any reason that your serial idea won’t work.

In one of discus discussions there was a guy who had

A 5kw Ac coupled GTI on Ac in, then Another 5kw on AC out.


I plan on doing something similar shortly, with a 500 multi on AC out for lights backup alone.

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boekel answered ·

What I usually do is either let the customer sell the old unit (they do well on the second hand market) or trade in the old unit.
If you replace the old unit with a 8k or 10k version, the upgrade is usually the simplest (if wiring is up to it).

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