Paul O'Flaherty is expected to see Eskom through the completion of its latest tariff application.
Eskom's financial director and head of group capital joins a number of executives who have in recent weeks resigned from state-owned companies, including SAA and Telkom, whose largest shareholder is the state.
There is increasing concern over the government's growing heavy-handedness in directing the strategy of state-owned companies, which are meant to operate independently.
O'Flaherty, leaving after three years in the position, told the Mail & Guardian he had "done the things I wanted to do" at the company.
He refused to comment on what his exit meant, particularly in the light of other high-profile parastatal resignations, but said he and Eskom chief executive Brian Dames were "very comfortable" with how things were running.
He confirmed there was not another offer on the table, which will ensure that a proper succession plan is in place when he finally leaves in July next year. A solid foundation had been laid to ensure a smooth handover, he said.
O'Flaherty is expected to see Eskom through the completion of its latest tariff application, as well as its next round of annual financial results.
Big loss
His resignation appears to have been on the cards for some months and the decision taken to make it public when the company's interim results were released.
Dames said on Wednesday that "between the whole board of Eskom, including the shareholder, nobody wanted Paul to leave". It was a "big loss" because he had a unique blend of IT, financial and construction experience, which was a large asset to the company.
But industry players and Eskom pundits are sceptical about the reasons given for O'Flaherty's decision to leave now.
Although Eskom has made headlines in recent years for all the wrong reasons, O'Flaherty has been a major player in righting a company that posted a R9-billion loss in 2009 in the wake of severe electricity shortages in 2008.
Posting its interim results this week, the company made a half-year profit of R12.6-billion, slightly down from R12.8-billion in the first half of 2011.
Following the government's panicked response to the power blackouts, Eskom committed itself to building the new Medupi and Kusile power stations in Limpopo and Mpumalanga without establishing a way to pay for them. When O'Flaherty arrived at Eskom, he was tasked with developing a funding plan and to secure financing for the company's R350-billion capital expenditure programme.
Latter position
Apart from his financial responsibilities, he has been pivotal in managing the company's new build programme. He came from Group Five with highly valued construction experience and filled the dual role of financial director and head of group capital, although Eskom wants to appoint a new person to take up the latter position.
"From an Eskom operational point of view, this is a disaster because the whole of the new build reported to him," said an industry player who did not want to be named. "He was needed there to keep tabs on costs."
The company recently announced its tariff application for the coming five years. But the increases of 16% a year will only be sufficient to see Eskom through to the completion of Kusile, set for 2018. Eskom has been calling on the government to provide direction about building new generation capacity in the coming decades.
There has been speculation that O'Flaherty, faced with trying to ensure the stable financing of an organisation of Eskom's size in the face of that level of policy uncertainty by the government, is leaving out of sheer frustration.
The Cabinet announced two weeks ago that Eskom would be the owner and operator of six new nuclear power stations, envisaged in the integrated resource plan, which is South Africa's electricity road map. This is a good indication that the state is going to push ahead with a nuclear procurement programme. But the question of funding remains a challenge. Eskom has already taken on extensive debt to pay for the new build, but continued tariff increases are sparking outrage among the public.
Given these pressures, O'Flaherty's resignation comes at a "critically dangerous period", said Chris Yelland, an Eskom expert and managing director of EE Publishers.
But, one analyst said, his departure was not expected to affect Eskom's current funding programme. Given that he would see the company through to its financial year-end, alongside a strong management team under Dames, the departure of one person would not have a severe impact.
Mayihlome Tshwete, spokesperson for Public Enterprises Minister Malusi Gigaba, said the resignation was an operational issue and the government fully supported the board and chief executive.