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Dual Multiplus II 2x120v units in split phase configuration

Can two Multiplus II 2x120v units be put in split phase configuration? The manual only describes using in parallel or three phase. I'm thinking of using just the L1 output from each inverter, similar to how the diagram shows for three phase operation. Any reason this wouldn't work?

Multiplus-IIsplit phase
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ahtrimble avatar image
ahtrimble answered ·

I am looking to do the same thing with my existing 5kWQuattro and the new one I am waiting to have delivered. I am running L1 from each inverter to L1 and L2 in my main circuit breaker panel. Then setting inverter #2 to 180 degree out of phase. And decoupling/ungrouping the inverters since I will have a 120v genset wired to only one of the inverters. And of course cabling the inverters as well. When I am done I will let you know how it will work out. Should be done within a month or so.

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solseekerssolar avatar image solseekerssolar commented ·
Thanks for the info. I believe your plan should work just fine.


We completed the installation for these units. They were wired using L1 from each inverter, fed to an Autotransgformer. Configured in split phase (180 degrees), all is working as hoped.


The only issue to overcome now is the data reported by each inverter to the Cerbo. When on shore power (50 amp split phase), L1 shows zero, or slightly negative power on both the input and output, while L2 displays properly. When inverting, the output is displayed correctly on both legs. I have not been able to test using a single phase shore power source, as all that is available at the site is 50 amp.


When using the regular Multiplus or Quattro, configured exactly the same, this reporting issue has not been present.


I am going to ask a new question in the group regarding this, with screen shots of what I am seeing.


Thanks again for your help. Good luck with your install.

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overlandrvs avatar image overlandrvs solseekerssolar commented ·
Did you ever figure out what this issue was? Getting ready to add a second multi II to exsiting (not my choice) and wired for split phase for mini split. Trying to decide if it should push to go in a different direction
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overlandrvs answered ·

What do you mean? Unit currently installed is Multiplus II 2x120 unit not even a year old. Going to add a second unit and wire for split phase which is why I was wondering if anyone figured out why the cervo gx would report incorrect information in this configuration. I know 2 multiplus would be better route but customer already has the multiplu II

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Curtis avatar image Curtis commented ·
Just curious how you made out as I'm dithering between the Multiplus-II 24/3000-70 2x120 split phase and living with 2400w total output on my 50amp rig, or going with 2x Multiplus 24/3000-70 with an Autotransformer for 2400w on each leg. If you were able to run 2 of the Multiples-II 2x120 with an autotransformer in split-phase with 2400w on each leg, then this would give me an upgrade path should 2400w prove to be insufficient...


Cheers!

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derrick thomas avatar image derrick thomas Curtis commented ·
Why not just run 2 of the 2x120 in parallel? While connected to 50amp shore you have full passthru on both legs, but when connected to 30amp or less single phase you have the combined output of both units on both legs for power assist. Best of both worlds. Of course if you have any 240 split phase appliances that would be a deal breaker. In that case dual multis (not 2x120) in split phase would be best.
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