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Adding a Multiplus to a system with a Quattro

Howdy.

My system is an off-grid solar solution, there is no grid and never will be. When I first set it up, I was unable to source a Multiplus, so I bought a 5K 120v quattro instead. It feeds a single 100amp autotransformer which I'm using as a step up to provide split phase 220v service. I'm looking at adding another inverter to support additional power draw. I believe, but would appreciate confirmation, that I can add a 5k 120 Multiplus to the system, instead of purchasing another Quattro. Would the best solution be to rewire the autotransformer from a step up configuration to passing through the two 120V legs from the two inverters?

MultiPlus Quattro Inverter Charger
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snoobler answered ·


From:

https://www.victronenergy.com/live/ve.bus:manual_parallel_and_three_phase_systems


"All units in one system must be the same type and firmware version; this includes same size, system voltage, and feature set. The type is indicated by the first four digits of the firmware version number."


If you want to parallel them, you need another Quattro. Period.


Completely Off grid too. I originally went with Quattros because there was no 48/5000 version of the multiplus at that time.

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dancing-skeptic avatar image dancing-skeptic commented ·
I don't intend to parallel them. Instead of putting 10k watts @120v into the autotransformer to step it up, I was thinking I could use a multiplus to give me 120v on one leg, while the quattro gives me 120v on the other.
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snoobler avatar image snoobler dancing-skeptic commented ·

Nope.

You've described paralleling them in split phase mode. Remember AC power is a sine wave oscillating at 60Hz. They must be in sync with each other to keep their place within the sine wave timing.

If you measured the output of the AT without them in parallel, the voltage between L1 and L2 would be anywhere between 0 and 240V.

Take the AT out of the equation. I believe you could use them in "parallel" with a common neutral, but you would only have two independent 120V legs - never 240V. Additionally, the two inverters could not be connected to the same grid/generator source.

If you want to add power, you either need to completely replace your inverter, or get an identical model and put it in parallel with your existing.

And are you certain there is a 5kVA MP around, or are you referring to the MP-II?


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dancing-skeptic avatar image dancing-skeptic snoobler commented ·
Thank you for the reply. I was afraid of that. I was referring to the MPII. Looks like I'll have to spend the extra $1k on another quattro.
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