South Africa's Public Enterprises Minister Pravin Gordhan says he cannot say yet when rolling blackouts will end, as power utility Eskom struggles with capacity shortages.
Eskom, which supplies more than 90 per cent of the power in South Africa, has suffered repeated faults at its coal-fired power stations.
Low water levels at hydroelectric plants, diesel shortages and loss of imports from Mozambique have contributed to the blackouts.
Around 17,000 megawatts of Eskom's installed capacity of 45,000 megawatts was unavailable, Gordhan said.
"Engineers are visiting the power stations themselves to give us an independent view of what is going wrong and how quickly we can repair what is going wrong," Gordhan told journalists on Tuesday.
"We need to complete these investigations, and we will come back to you in the next 10 to 14 days."
Eskom has continuously implemented power cuts since Thursday, with up to 4000 megawatts cut from the grid on a rotational basis.
The power cuts have disrupted businesses, particularly small and medium-sized firms, and prompted frustrations ahead of an election in May.
Apart from faults at the new Medupi and Kusile mega power plants, three other coal-fired plants were suffering severe problems, Eskom executives said.
The executives also said Eskom was expecting to receive a diesel shipment on Friday to replenish its fuel supplies.
Australian Associated Press