Eskom said on Tuesday power will remain tight during the southern hemisphere summer period as it increases maintenance work on its ageing fleet, coupled with delays in bringing electricity from new plants online.
Eskom CEO Brian Dames said more maintenance was done during this year's winter period, which runs from May to August, compared to the same period in the three preceding years, but more work was needed.
"Summer is typically maintenance season, but this summer maintenance will increase as most of the maintenance cannot be deferred," Dames told a news conference.
"With the maintenance that needs to be done, the system will remain tight."
Eskom, which provides 95% of the power to Africa's biggest economy, has been walking a tightrope for five years as it tries to bring long-overdue power plants online after the grid came close to collapse in 2008.
The utility said in July that the first power from its new Medupi plant would hit the grid in the second half of next year, a delay of at least six months caused by labour unrest and "underperformance" by contractors.
The South African cabinet last month gave Eskom a go-ahead to build another coal-fired power station. The size and costs of this project have yet to be determined.