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mikebamber avatar image
mikebamber asked

MultiPlus ii Parallel Question

Hi, currently running an MPii with 4x Pylontech US2000s. Everything is great. I don't use the AC out, it's running as a grid tie ESS. Using solar too on the AC side.

What I want to do is add a second Multiplus with a different type of battery (thinking EVE LiFePo4 cells and Batrium BMS).

If this works then I can scale the system up over time with more MPs.

Is this feasible? or do both the multiplusses need to be connected to the same battery?

multiplus in parallel
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mikebamber avatar image mikebamber commented ·
Am I overthinking this? Can I just add more Multiplus devices to the AC IN supply, hook them all up to the Cerbo and they'll be happy?
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Alexandra answered ·

@mikebamber

If they are being programmed as parallel then they share a battery bank.

There is some more documents and information linked in the related resources box on this page - to the right on laptop - to the bottom on mobile.

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mvas answered ·

How does the existing MultiPlus know when it is OK to recharge the battery bank? Time of day? Do you have TOU electric rates?

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mikebamber avatar image mikebamber commented ·

I manually schedule charge time, also the battery charges from surplus solar.

So can you confirm that the proposed system is OK? Would they operate effectively as a master unit and 'see' two batteries?

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Alexandra avatar image Alexandra ♦ commented ·

It is a requirement for Victron - it is in the manual.

if there is a voktage difference - if there is an amp difference - they will perform differently and not load share.

There is if they they do not share the load equally one bank will deplete faster than the other - one unit will then shut down before the other and then you will see errors on the GX - for example error 3
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mvas avatar image mvas Alexandra ♦ commented ·

What "load sharing" are you talking about? There is no load on AC OUT.

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mikebamber avatar image mikebamber Alexandra ♦ commented ·
So I'm not sure if it's relevant to your reply @Alexandra but I'm not using the AC out, just using AC in in a grid-tie config.


@mvas yes I'm on a TOU electric tariff but also I have a lot of solar panels.

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mvas avatar image mvas mikebamber commented ·
People may think that your MultiPlus will be sharing a load on AC OUT because you used the word "parallel", as in a "Master / Slave" Parallel configuration, in your title. Are going to enable "Master / Slave" Parallel mode configuration for load sharing? Do you have a Cerbo?
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mikebamber avatar image mikebamber mvas commented ·
I have a cerbo, yes.

This is why I'm asking the questions - I'm trying to find out if it is possible to make the two (or more) units act as one or whether they need to be run and controlled as separate systems. Bear in mind I would potentially like to go beyond two units.

Can I assume at least that they will happily sit on same AC supply together?

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Alexandra avatar image Alexandra ♦ mvas commented ·
Why even have the inverters if there is no load on them?

I guess we are using terminology differently here.

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