Batronca - great question; I liked the automatic user interface to be able to do everything on its own as we are not at the home half the year and I jumped the gun without knowing about the two phase. However - what we did was we connected the 18KPV to a two-phase subpanel for the apartment that powers the pool motor and an instant hot water heater.
It is connected to a 50 circuit breaker; 50 from the main panel to the 18KPV and then back to the main panel 50 breaker which is connected to the subpanel in the apartment; maybe in due time we will upgrade to another inverter to make best use of the 3 phase; but at this time I think this is what is best as we can't connect a 3 phase to a single inverter as per Signature Solar.
We have the unit running however going to give Signature Solar a call to commission it and upgrade all the firmwares on Monday.