Eskom acknowledges that transmission constraints remain an obstacle to the introduction of new renewables generation, but the utility also highlights that 32 GW of grid capacity is immediately available to those independent power producers (IPPs) willing to build projects outside of the country’s prime solar and wind regions.

Renewables developers have hitherto targeted the Northern, Western and Eastern Cape provinces, owing to the fact that the solar and wind resources in these regions are among the best globally and superior to those in South Africa’s other six provinces.

A recent survey comprising more than 240 contributions from members of the country’s renewables associations indicates that, while wind and solar projects with a combined capacity of 64 GW are being considered for development, 57 GW of that potential is proposed for development in a region where there is only 5 GW of residual grid capacity available.

Eskom’s most recent Generation Connection Capacity Assessment shows, for instance, that the Northern Cape is saturated, while the Western and Eastern Cape have less than 3.5 GW available – a figure that was enlarged to 5 GW as a result of a decision to curtail dispatchable capacity from the open-cycle gas turbines in favour of renewables.

Strategic grid planning manager Ronald Marais says that the survey results have validated the grid-development approach Eskom is pursuing under its Transmission Development Plan (TDP), which includes transmission line and substation investments aimed at unlocking the generation potential of the Cape provinces.

However, the TDP projects will take time to implement, and Eskom is thus pursuing a specific intervention in parallel in an effort to attract wind and solar investors to Mpumalanga, where the grid constraint is far less acute.

The utility is running a competitive process for the lease of grid-ready land to IPPs seeking to take advantage of a recent market reform allowing distributed generation projects below 100 MW to proceed without a licence, even when the electricity will require wheeling over Eskom or municipal networks.

Marais told delegates to a recent RES4Africa Foundation conference that Mpumalanga has about 6.5 GW of grid supply area capacity, which could be unlocked by developing some additional distribution infrastructure.

“Because most of the coal stations in the province are directly connected to the transmission system, there is no distribution infrastructure, which would have to be developed to bring the electricity produced by the renewables generators back to the substations that are connected to the transmission grid,” Marais explains, likening the distribution infrastructure to on-ramps to a highway that would otherwise be bypassing the area.

Besides Mpumalanga, however, there was also grid capacity in KwaZulu-Natal (6 GW), Gauteng (4.5 GW) Free State (4.1 GW), the North West province (3.5 GW) and Limpopo (2.5 GW).

However, the survey of IPPs pointed to a material mismatch between preferred projects sites and available grid capacity, which had led Eskom to conclude that only 19 GW of the 32 GW of available grid capacity was likely to be taken up by utility scale renewables investors in the near term.

Marais, therefore, urges ongoing collaboration between the renewables industry and Eskom to further investigate ways to unlock the capacity that is already available, as well as to ensure better planning for future grid infrastructure.

The utility is hoping to accelerate future grid connectivity through a spatial planning approach that ensures that new renewables projects are developed in “clusters” around the major corridors.

“Solving the grid constraint problem will require collaboration, as Eskom will not on its own be in a position to find the solutions,” Marais stresses.