Please help me choose: single phase vs 3 phase HVAC compressor
That's a crazy-large unit for a house.  That's why he was stuck with 3-phase.

Stand-by power consumption on that inverter is 240 watts.  That will cost you between $240 and $500 per year in electricity simply to have it idle depending on your local electricity prices.  

Generally there's no earthly reason to go from single-phase to 3-phase (variable frequency drive for tools notwithstanding).  

Single phase motors aren't significantly less efficient; if they were, they'd need enormous cooling fins. Because inefficiency turns into heat. 

I think you're better off with 3 units instead of one. Not least, if one fails, it's not such a big deal.