Eskom has provided further details on the distinctive roles it envisages being performed by the National Transmission Company South Africa (NTCSA) in relation to the transmission system when compared with the yet-to-be-established Transmission System Operator (TSO).

Under a newly approved unbundling framework, the NTCSA is set to remain a wholly owned subsidiary of Eskom Holdings and retain ownership of the transmission system assets, while the TSO will be established as a new State-owned company outside of Eskom Holdings.

The TSO is expected to be the transmitter, the system and market operator, the central purchasing agency and be responsible for ancillary services, such as frequency control and voltage regulation.

The Electricity Regulation Amendment Act, which came into force in early 2025, set a five-year timeframe for the creation of the independent TSO, which is seen as important for levelling the grid-access playing field in a future competitive electricity supply industry.

Statements released by Eskom and the NTCSA pointed to a potential overlap in responsibilities for the grid, however.

In Eskom's statement, it was indicated that besides owning the grid assets, the NTCSA would be responsible for expanding the high-voltage transmission grid and rolling out the Transmission Development Plan (TDP).

The NTCSA statement indicated that the TSO would develop and execute the TDP, maintain and operate the transmission grid, and provide non-discriminatory access to that grid to all market participants.

In a response to an Engineering News enquiry seeking clarity on which entity was responsible for maintaining and operating the grid, Eskom said that the NTCSA would remain the licensed, regulated owner of the transmission assets within the Eskom group and would be responsible for financing, constructing and maintaining the physical grid, including the build associated with the TDP.

The independent TSO, meanwhile, would perform what Eskom described as the functional ‘transmitter’ role: it will develop and approve the TDP, operate the power system, run the wholesale market, act as the central purchasing agency and provide nondiscriminatory access to the grid for all market participants.

The NTCSA, it added, would implement the TSO’s plan through regulated and arm’s-length commercial arrangements, with the National Energy Regulator of South Africa overseeing both entities’ licences and conduct.

“The apparent overlap arises because both descriptions refer to the same value chain, but from different angles.

“The TSO will decide what grid is needed, where and when, and will manage system and market operations; the NTCSA will be responsible for building, owning and maintaining that grid in line with the TSO’s plan.

“These complementary roles will be formally codified in legislation, licences and commercial agreements to avoid duplication and ensure clear accountability,” Eskom explained in its response to Engineering News.