South Africa’s national electricity utility, Eskom, has announced that it is availing about 3,470MW in grid capacity through curtailment as revealed in the addendum of its Generation Connection Capacity Assessment 2025 (GCCA 2025).
Eskom uses the Generation Connection Capacity Assessment (GCCA) to inform stakeholders of the potential capacity available on its transmission network to facilitate connection of new power generation projects.
“The GCCA 2025 Addendum provides the 2025 connection capacity with curtailment for energy generators and serves as an addendum to the GCCA 2025 published in October 2023,” said Eskom’s Transmission Group Executive, Segomoco Scheppers.
The utility outlined that it will introduce a 10% curtailment measure which would unlock 2 680 MW of grid capacity in the Western Cape, and 790 MW in the Eastern Cape.
Curtailment involves the deliberate reduction of output from power plants in response to system security needs or temporary transmission capacity constraints. Curtailment has been widely used by system operators to facilitate the introduction of renewable generators in a context of grid constraint.
“Unlocking capacity in these areas will require a significant amount of transmission network investment, which takes several years to develop and construct,” said Eskom. “The option of curtailment therefore provides developers with an alternative if they are still keen to connect in the constrained grid areas.”
“By accepting a reasonable share of curtailment, the generation connection capacity for constrained areas can be safely increased,” Eskom adds.
When the grid limit is reached, any further increase of generation in the supply area leads to grid congestion. In such cases, and in order to remove the congestion, generation has to be reduced.
Eskom says curtailment helps maximise effective use of the existing grid and increases generation connection capacity.
The utility revealed that its curtailment plan has passed through its internal governance process and has been approved to a large extent. The utility also confirmed that the regulatory support curtailment was confirmed by NERSA in December 2023.