Eskom acknowledged the level of failures was "unacceptably high".
Miners were hamstrung by unprecedented stage six load-shedding in December and the Minerals Council South Africa labelled power security a priority earlier this year, as it called on the government to take urgent steps to address the country's economic crisis.
By last week, there had already been more power outages in 2020 than in 2019, according to data attributed to South Africa's Council for Scientific and Industrial Research.
On Friday Eskom said there was 5,000MW of capacity on planned maintenance, and 10,950MW on breakdowns, with a 3,000MW energy demand deficit aggravated by very high demand during the cold weather.
It said the issue had been exacerbated by "apathetic" management.
It suspended two power station managers and had deployed senior managers to provide oversight at four stations and said the previous culture of weak consequence management would no longer be tolerated.
"The board is pleased that some units have since returned to service, but is aware that the level of failures is unacceptably high," Eskom said.
"Whilst it is true that the ageing fleet is plagued by legacy issues of neglect and omitted maintenance and is therefore susceptible to unpredictable breakdowns, it is also true that the situation is exacerbated by serious issues of apathetic behaviour by some management staff."
The country was facing stage one load-shedding today, escalating to stage two again this evening, Eskom said on Sunday.
The Department of Mineral Resources and Energy last month issued a request for proposals for a risk mitigation independent power producers procurement programme.
The programme is looking to procure 2,000MW from a range of energy sources, alleviate supply constraints and reduce the use of diesel-based peaking electrical generators.