The NEM (National Energy Market) is doing fairly well on rooftop and PV Solar. Current growth is actually causing problems as typical base load power (coal & combined cycle gas) are becoming uneconomical during solar hours. As the NEM covers the east coast and south Australia (at least major population centres), that doesn't leave much place to sell it. WEM (Western Australian Energy Market) is more regulated and have their own PV capacity.

The only way this could be economical into Australia would be if it had an energy storage capacity. Someone might do the math and build a battery to be powered from this and inject into one of the grids, but longer term, if it is to supply singapore, it makes more sense to put the batteries at the singaporian end.