I don't really like blogging about South Africa so I'll keep this short. There is a very simple way to ration South Africa's "fixed supply" of electricity; raise the damn price. Worried about the poor? Give them money. Who knows, with higher prices for the same amount of electricity, Eskom might even be able to use the money to build more capacity sooner (this is partly what profits are for by the way, investment for the future).
Also the whole saga reveals a pretty entrenched bias about the way "we" think about economics. The world markets have been in trouble recently so cue the amusing columns predicting the final collapse of capitalism and the more earnest brow furrowing articles about the need to regulate capitalism's excesses so that this kind of thing will never happen again. When government screws up though we don't get many outraged denunciations about the excesses of government (well maybe you do, but only in pretty niche publications). Instead we get grand plans which curiously involve more government involvement. Seems like clear anti-market bias to me.