Eskom’s grid is under increasing pressure from the rapid growth in private generation projects, with the Eastern, Western, and Northern Cap having no capacity to add new generation projects.
This was revealed in Eskom’s Generation Connection Capacity Assessment of the 2025 Transmission Network.
South Africa’s grid is designed to carry electricity from large, central power stations in the country’s northeast to other parts.
Renewable energy generation is decentralised, with generation facilities located almost anywhere.
The areas, such as the Western Cape, Eastern Cape, and Northern Cape, which have rich renewable resources, do not have the grid capacity to distribute electricity to the rest of the country.
The grid in these areas can only carry limited load, which is insufficient for large-scale projects.
Chief engineer at Stellenbosch University’s Centre for Renewable and Sustainable Energy Studies, Monique Le Roux, said earlier this year that this will become a problem in other provinces if the rapid growth continues and Eskom does not upgrade the grid.
“It will be very interesting to see how Eskom navigates this problem and keeps the grid stable,” Le Roux said.
“If too many people install solar generation, then the transmission lines will be overloaded and have to run at peak capacity, which causes damage to the lines.”
Le Roux warned Eskom might even have to step in and “tell customers to shut down their solar generation during particular times to prevent their lines from failing”.
“This may get to a situation where the transmission grid just cannot handle the amount of energy being generated, and people would have to shut down these systems or disconnect them from the grid.”
The other solution is for Eskom to upgrade the country’s grid rapidly. However, this will cost hundreds of billions of rands and take years to complete.
Eskom has a transmission development plan to tackle this problem, requiring hundreds of billions of rands to build infrastructure nationwide.
The utility aims to build 14,000 km of transmission lines over the next decade, costing an estimated R372 billion.
However, this amount has increased substantially as the private sector has begun rolling out large-scale renewable energy projects in areas with little to no grid capacity.
The utility has said it will need an additional R100 billion in the 2025 financial year to execute its transmission development plan. This amount will increase annually to R170 billion in 2029.
Of particular concern is that the provinces with the best resources are the Cape provinces, while those with the best infrastructure are in the country’s northeast.
“What we are going to see over the next 20 years is that our grid is going to flip 180°, with the bulk of the generation capacity in the Cape provinces,” Swilling said.
To complete this flip, South Africa must build 2,300 km of transmission lines annually. Currently, the country only produces 400 km of lines a year.
The maximum length of transmission lines built annually was 1,800 km in the 1990s.