The houses are connected in balance across the three phases, on installation. Yes, it is likely that any solar installs would disturb that balance, but....
Generation from these facilities is not of sufficient energy density to make a difference. Even with the new development you note, even if they are all 1500W installations, at peak output they are only developing 6.25 amp per inverter. (Assume no losses). It seems hard to believe that the distribution system is incapable of dealing with such (net) reverse currents as are created.
Each house (and especially the group of houses on a feeder comprising solar and non solar installed) are going to have a variety of parasitic loads - fridges, computers in each room and one for the kennel, idling TV loads. Especially in newer developments, with new families, the other whitegoods will be in use - again across a variety of the households on the feeder.
In Vic, the program was halted at around 500MW installed. Across Vic peak load of 8500 winter and 10-11,000 summer it is quite small, given the disparity between capacity and output with rooftop solar. Basically the distribution system is designed to deal with current flow from substation to house at peak useage. Solar is not a strategic problem.
I agree with the poster above the Qld problem is a asset deterioration problem - not a solar issue. f111
