In the rapidly evolving landscape of South African energy, the Generation Connection Capacity Assessment (GCCA) stands as a key input in helping stakeholders understand the dynamic changes taking place in terms of our energy generation mix and, critically, how that maps to current and planned grid capacity.
I. The Core of GCCA 2025: Understanding Generation Connection Capacity
In essence, the GCCA 2025 focuses on generation connection capacity. This is crucial for determining how much new generation can be accommodated by the transmission system at specific locations and times, without compromising grid reliability or necessitating substantial infrastructure upgrades. This capacity isn’t static; it fluctuates with changes in network upgrades, demand, and the addition of new generation sources.
Furthermore, the GCCA 2025 report suggests that it is insufficient grid connection capacity that is currently one of the primary impediments to bringing new generation projects online at the scale and pace that is required to improve South Africa’s energy security (as is also the case in several other energy markets, most notably Australia, the UK and much of continental Europe).
II. Regional Capacities and Constraints: A Detailed Overview
The GCCA 2025 report delves into the specifics of generation connection capacity across the country. It reveals areas where existing capacity has been exhausted, primarily in regions rich in renewable energy resources, resulting in viable generation projects that are not being built due to the inability to secure a grid connection. The report categorizes capacities at four different levels – substation, substation area, local area, and supply area – providing a granular view of grid availability.
Figure 1: Summary of GCCA 2025 Results
As is illustrated by the figure above, the GCCA 2025 reports that the Eastern Cape, Western Cape, Northern Cape, and Hydra Central have 0 MW additional available capacity. Capacity in these regions – known to be favourable for wind and solar PV generation – has been depleted by previous REIPPP rounds as well as by the development of projects for private offtake. This may also reflect the fact that renewable energy uptake has far surpassed the planned allocation for renewable energy outlined in the Integrated Resource Plan (IRP) 2019 and Transmission Development Plan (TDP). The IRP 2019 and TDP forecast 15 GW and 13.8 GW installed capacity respectively for renewable energy procured by 2025 while the GCCA shows that renewable energy penetration for 2025 – based on committed capacity – is already at 18 GW.
Figure 2. Power flows through the transmission network.
As is shown in Figure 2, the take-up of available grid capacity in the Cape provinces and Hydra Central will also result in power flowing via other supply areas towards the larger loads in Gauteng, Kwazulu-Natal, and North-West Province. With some of the generation from the Cape provinces competing for a shared corridor through Hydra Central, available grid capacity is further limited for specific supply nodes as well as for Hydra Central itself.
III. The Road Ahead: Opportunities and Challenges
One of the key insights from the GCCA 2025 report is therefore the need for significant investment in the transmission network. This investment is crucial to unlock grid capacity in areas with the best wind and solar resources. Unfortunately, despite being highlighted as an economic priority nationally via NECOM, it appears that the necessary transmission corridor improvements will only be commissioned from 2027 onwards at the earliest.
As an alternative solution for projects in constrained areas, the report also explores the concept of curtailment of generators. While it was not included in the GCCA 2025 report at the time of its original release in October 2023, industry engagements suggested that curtailment might be an effective solution to mitigate grid constraints in relation to wind projects, with co-located battery storage as an alternative for solar PV plants. In line with this thinking, the addendum to the GCCA report, released in January 2024, indicated that 3 470 MW additional grid capacity could be unlocked through 10% curtailment for wind projects in the Western and Eastern Cape (divided into 2 680 MW and 790 MW in the Western Cape and Eastern Cape respectively).
IV. Strategic Questions for Stakeholders
For stakeholders looking to navigate this complex landscape, the GCCA 2025 report is therefore a valuable input to decision-making. At a most basic level, it suggests – at least for now – to focus development activity in areas with remaining capacity, albeit with less favourable conditions for wind and solar generation, as is illustrated in Figure 3 below.
Figure 3. Summary of Committed IPP Generation.
That said, the report also prompts a number of questions in assessing how South Africa’s energy landscape might evolve in light of the emerging grid capacity constraints. These include:
- To what extent should investment be directed (and incentivized) to utilising areas of existing capacity versus prioritising further grid build-out?
- How should private vs. public procurement processes be considered in grid allocation given limited grid capacity (and a legal framework that requires equal access)?
- How should trade-offs between ‘firm’ and ‘variable’ generation be assessed (given the requirement for equal access)?
- To what extent should the wider commercial and regulatory framework reflect the realities of grid scarcity (for example: in considering point-to-point wheeling costs rather than zonal proxies)?
- If curtailment is a means to address capacity constraints, how should those costs be borne? And how can lessons from energy markets like ERCOT in the US be incorporated?
- How does the role of the private sector differ from that of Eskom in relation to funding and executing the necessary grid build-out?
- If grid build-out is one of the greatest constraints to achieving cheap and secure energy supply, what are the most significant bottlenecks and how can they be solved?
v. Conclusion: Embracing a Sustainable Energy Future
As South Africa continues its journey towards a more diverse energy mix, understanding the implications of constraints in our grid capacity becomes increasingly important. In that context, the GCCA 2025 report is a helpful input in highlighting some of the challenges, opportunities, and potential strategies to manage that transition successfully.
