question

There have been previous discussions on this forum about doing what you suggest. There is also a system diagram showing such a system but with an autotransformer to create 120/240 split phase:

AT-1 split phase 240V to 120-240V with Quattro 240V

If all your loads are 240 volt then you would not need the transformer.

As far as I can tell, none of the Quattro or Quattro II models are UL certified. Only the 120 volt MultiPlus models have a UL certification.

I am researching a very similar topic, and trying to remember a lot of my college electronics/physics education from many years ago. In my case, I'm designing a fully off-grid cargo trailer as a workshop, where all power comes from solar and a lifepo4 battery bank.

I do wonder whether there's really a need for an autotransformer in the system design. The small 240v mini splits I'm looking at often have a rated current of less than 5 amps. For example, a Senville 12000 BTU SENA-12HF-Q has a rated 3.72A when cooling, and 4.1A when heating. If the mini split is the only 240V load, perhaps imbalanced power draw on the 120V phases is manageable. Or to put it another way, if you have two 15A 120V circuits, and an inverter that can supply 20A 120V to each side, then a 240V load that pulls less than 5A doesn't need to worry about unbalanced 120V loads? It seems like in this scenario, one could save on the expense of adding an autotransformer to the electrical system. Or am I being overly naive about how these systems work?