A 15 min google search

Za current renewables are at r 2,02 kwh ( 2012)

15 year life span

but customers are paying r1, 62per kwh

So coal must be cheaper than renewables

Also most heavy users are in the north most energy renewables are in the south

Za do not have transmission capacity to take the power to the north so having more renewables will not help

Apparently transmission capacity is at 100% in the south