Electricity demand reduced
Eskom's objective is to install one million solar water heaters throughout country by 2015, with tens of thousands already installed in other cities around the country.
The company is offering 110-litre geysers for free in township homes, but wealthier families needing larger volumes also receive a subsidy to encourage them to switch to solar.
Eskom has so far spent R340m on its rebate programme.
"Eskom and government's joint objective is to save energy and to encourage the use of renewable energy, as well as to provide relief to low income households," said Eskom spokesperson Hillary Joffe.
The solar project has already reduced the demand for electricity by 22MW, she said.
That's a tiny fraction of the power produced by a coal power plant, but about one-fifth of the electricity that would be generated by a planned solar field in the arid Northern Cape.
Massive new coal plants are being built to cope with South Africa's energy needs, but international loans for those projects have also required the country to commit more resources to renewables.
The country already emits half of Africa's greenhouse gas emissions, mostly from coal-powered power stations.
The African Development Bank earlier this month approved a $365m loan to help fund Eskom's wind and solar projects.
The country is also keen to be perceived as more environmentally friendly in the run-up to UN climate talks in November in Durban, which will seek to create a deal to follow up on the Kyoto Protocol.