In a solar system, phase refers the distribution of an energy load. Single phase refers to a power circuit with two wires, the power wire and the neutral wire. Three phase refers to a power supply with three power wires that are 120 degrees apart.
Difference between configurations
Residential homes usually run on a single-phase power supply, meaning they have only have one wire coming in from the grid. Three phase systems are meant to accommodate higher loads such as: large air conditioning, pool heater, spa, sauna etc. A three phase also means you can send more solar energy back into the grid, for those with a battery system or has a big system.
Why get a three-phase power supply?
In South Australia, you can currently have up to a 5kw Solar system on single phase whilst up to 30 kw Solar system on three phase. A three-phase circuit is more efficient, as you are spreading the load over more wires, this means it can avoid voltage-rise related solar issues which is caused by too much voltage at a time.