Unlocking Grid Access: How Congestion Curtailment Supports South Africa’s Just Energy Transition
We are at a defining moment in South Africa’s energy journey.
Independent Power Producers (IPPs) are ready to drive the growth of renewable energy projects; however, grid constraints – originally in the resource rich Cape Provinces, but now also across parts of the Freestate and Northwest Provinces – have halted development. This reality hit hard in Bid Window 6 of the REIPPPP, where no wind energy projects were awarded and Bid Window 7, where less than 30% of the 3,200MW procurement capacity allocated to wind energy projects was awarded, but subject to challenging value for money discussions. This wasn’t due to a lack of resources or developer interest. It was the grid that stood in the way.
That’s where the Congestion Curtailment Framework comes in. Historically, NTCSA has determined available grid capacity by considering that each generation facility should be able to export its full rated power at all times. This means that the grid needed to be designed and built to handle the load flows during periods of peak generation and low load demand which requires over investment in transmission infrastructure that is not needed most of the time (e.g. periods of non-peak generation). NTCSA has since conducted studies and determined that it is more economically efficient to determine grid capacity taking into account a reasonable level of curtailment. NTCSA put the proposed Congestion Curtailment Framework together and applied to NERSA for approval to implement. NERSA approved the implementation of the framework in April 2025.
The framework, once implemented, allows new generation capacity to connect to the grid now instead of making them wait for years for capital intensive new transmission lines. During periods of peak generation and low load, a generator’s power output may be temporarily scaled back. What makes this framework bankable is that curtailed generation is recognised by NTCSA as an ancillary service. This means that NTCSA will continue to credit off-takers of wheeled energy during periods of curtailment as if the curtailed energy had been delivered. Thus, generators are able to be compensated for curtailed energy by the off-takers.
The impact is clear. The Generation Connection Capacity Assessment (GCCA) 2025 showed zero available capacity in the Cape and the southern part of the Freestate Provinces. But once NTCSA applied a 10% curtailment allowance (which in reality will be far less), 3,470 MW of new capacity became available—2,680 MW in the Western Cape and 790 MW in the Eastern Cape.
Economically, the case for the Congestion Curtailment Framework is sound. Over 25 years, building new grid infrastructure would exceed the cost of curtailed energy, even when taking unlikely extremes of curtailment into account. Renewables remain far cheaper than other options (i.e. grid expansion, load-shedding, and gas turbines). Even with some curtailed energy, the bulk of renewable output reaches the grid, delivering clean and affordable power.
The Congestion Curtailment Framework represents a real shift: faster access to the grid, financial certainty, and a transparent process aligned with national energy goals.
For Anthem, this framework is about more than numbers—it’s about keeping the Just Energy Transition moving. It helps integrate renewables faster, reduces reliance on fossil fuels, creates jobs, and ensures fairness by compensating both public and private IPPs. Consumers are protected too, since curtailment costs are capped. There are safeguards in place. The framework runs for three years (2025–2028), with curtailment capped at the existing ancillary services budget. Further, NTCSA must report every six months on curtailment levels, costs and progress. For now, it’s understood to be limited to the Western and Eastern Cape, where constraints are most urgent, while further studies are done before considering expansion.
It’s important to remember that the Congestion Curtailment Framework is not a replacement for grid expansion but is a tool to manage the efficient use of the capital deployed in the grid, thereby maximizing the return on investment in the grid, which is ultimately funded by everyday South Africans. The framework provides the bridge we need today-unlocking capacity now while building a stronger, more resilient, and sustainable grid for tomorrow.