Eskom says it will start rolling blackouts countrywide on Sunday, due to a loss of capacity at its Majuba power station in Mpumalanga.
It says in a statement a crack in a coal storage silo caused the loss of 1800MW.
The power shortage is expected to last the entire week and blackouts will happen between 8am and 10pm.
The silo, which stores over 10,000 tons of coal, cracked on Saturday afternoon, and this affected coal supplies to all six units at the power station.
Eskom says teams are in the process of dispatching mobile coal feeders to the site, while engineers are investigating the cause of the crack.
Power outage schedules are available on Eskom’s website.