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greg-mercer asked

Victron Multiplus - Combine with second for 230v?

Hi.

My current setup is below. I'm am fully off the grid. I have a large battery bank and 3000w of solar. I currently run House A off my multiplus with my generator as backup. I only run House B off my generator. It currently uses 240v for the AirCon, but, my AirCon just broke and I need to install a new one.


I have two things going on right now. 1) I want to expand my Victron system to power House B off my solar/battery setup AND 2) I need to replace my AirCon, so, could replace it with a 120v system. The 120v systems use more power, but, I wouldn't need to worry about 240v anymore.


Questions:

1) Would you go through the hassle of getting 240v setup with a Victron system, or take the efficiency loss and keep it simple with 120v? (240v AirCons are available in 33 SEER, 120v only go up to 18 SEER)

2) If I want to go with the 240v, I assume this is what I need to do. Please let me know if I'm correct.

  • Get one more Multiplus 3000 and set them up to run in Split phase
  • Power both Multiplus from receptacle #4 set to 240v. One hot wire would go to Multiplus #1 and the other hot wire would go to Multiplus #2. They would share the negative and ground wires.
  • The max out of receptable #4 is 22.9a x 240v = 5500w (the generator max) so we're all good there
  • The 240v AirCon unit would get power from both hot wires, 1 exiting Multiplus #1 and the other exiting Multiplus #2
  • House A would get its 110v from Multiplus #1, House B would get its 110v from Multiplus #2 to try and keep it balanced.

3) Will the split-phase stay in sync with this setup? Or if they're unbalanced, will the phase get messed up? Do I need a Victron Autotransformer?


THANKS for you help!!!



HONDA EU7000IS GENERATOR INFORMATION


MultiPlus Quattro Inverter Charger
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1 Answer
ben avatar image
ben answered ·

1) I can't answer without knowing more about your budget and expansion goals for house 1. In the long run, I generally like the high-SEER units, so I would tend to lean that way.

2) I believe your plan will work, but you'll need load assist from the battery to handle the fact that your 240V air conditioner (whose demand you have not identified, by the way) will be split across the two generator coils. In other words, half of the 240V air conditioner will end up loading the same leg as all of House A's loads.

3a) The split phase will stay in sync. They don't really care that there are multiple distribution panels downstream, which is really what you have. (I suppose your inspector might care, if you have to comply with some kind of code. I don't know about those.)

3b) An autotransformer placed across the split phase legs would rebalance the two. In practical terms I'm not sure that this gets you much, but it may improve your generator's performance envelope a little. If you're going to use a transformer, though, you could alternatively just have it step up a 120V supply to the 240V you need for your single air conditioner in House B. In that scenario you would just have two, separate 120V inverters running in parallel.

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