Johannesburg - Power cuts would continue across the country on Saturday, Eskom said.
"The load shedding continues this morning [Saturday] as planned, we have implemented stage two of load shedding," said spokesperson Andrew Etzinger.
The power utility implemented rotational power cuts on Friday.
It said the power system was "extremely constrained".
"The power system is extremely constrained... due to unforeseen technical problems at power stations, depleted water reserves at our peaking power stations, which use water to generate electricity, and depleted diesel reserves to fire up the open-cycle gas turbines," Eskom said on Friday.
Load-shedding schedules were available to Eskom's direct customers on its website. Customers could also contact their call centre for additional information.
Earlier this month, a coal storage silo at the Majuba power station in Mpumalanga collapsed, resulting in widespread power cuts. The silo held more than 10 000 tons of coal and affected coal supplies to all six units at the power station.
An investigation is under way.