Stage 5 load-shedding is in force until 8pm on Wednesday when stage 6 will be implemented.
The daytime outages were at stage 4 on Tuesday.
The heightened stages of enforced power outages are due to insufficient generation capacity and the need to further replenish emergency reserves, Eskom said.
Load-shedding at stage 5 will apply between 5am and 8pm, with stage 6 in force from 8pm to 5am.
This pattern will be repeated daily until Saturday morning.
Eskom’s announcement comes hours after the energy utility said Kusile’s unit 2 was synchronised into the grid.
“This marks another significant milestone in the Eskom generation operational recovery plan which aims at increasing the energy availability factor to 70% by March 2025.
“The unit will add 800MW to the grid.
“The additional three units provide 2,400MW, which translates to two-and-a-half stages of load-shedding. With the three units back in service, Kusile in total will be generating 3,200MW.”