Eskom says that stage 2 load shedding will continue until 6 a.m. on Sunday morning due to a loss of additional units.
"While we expect three generation units to return to service [on Friday], we lost a further two units last night to unplanned breakdowns," the utility said in an power update.
Unplanned outages increased were at 11 562MW on Friday morning, a slight decrease from 12 225MW on Thursday afternoon.
The cash-strapped utility has warned of an increased likelihood of power cuts over the next 18 months as it conducts maintenance on its fleet of ageing power plants.