Here is an interesting article on three phase power and inverters. ARTICLE
Note the mention of dropouts using a single phase.
You would also have to find out if your current metering system supports measuring feed-in to the grid or you require a new metering system.
AGL have recently changed their rules and no longer have a 10Kw limit on the system size. (However your supplier may have local limits on systems and you should check on this)
I suggest you really read up on this subject as you will see that using a single phase for feed-in you may not be getting the full benefit of your system.
If it was me I would be going for a three phase system.