You didn't describe if the solar is generating electricity, heating water? A mini-split has the output end (fan and controls) in the space to be treated and the functional end (heat pump, natural gas or electricity as the input used to generate heating or cooling air to the output) outside, separated; not like a wall unit, which is a space heating/AC unit all-in-one, and not like a central system with zones. That's why it can be high efficiency. I don't see how solar ties into this other than, it might be how they generate the electricity used by any appliance.