High danger of load-shedding in South Africa

Eskom’s unplanned power station unit breakdowns have reached a concerning level, suggesting that the power utility is barely dodging load-shedding.

Eskom’s latest weekly system status outlook shows that its weekly average EAF reached 60.47% during Week 24 of 2025 (9 to 15 June 2025), an improvement from the 60.03% in the previous week.

It is also substantially better than the 57.19% reported in the first week of May, when Eskom briefed the public on its 2025 winter load-shedding forecast.

However, the EAF is markedly lower than the 63.10% it was in the same week last year. In addition, Eskom’s unplanned capacity loss factor (UCLF) has shown a troubling increase.

The UCLF increased from 28.08% in the first week of May to 30.73% in mid-June. This is over six percentage points higher than the UCLF at the same point last year.

Eskom’s data portal also showed that the monthly average of unplanned outages was at its highest level in 12 months.

Eskom has partially attributed the rise in UCLF to delays in returning 1,800MW of capacity to service from planned maintenance, including the 800MW from Medupi Unit 4.

This unit has been offline for nearly four years after a catastrophic explosion damaged its generator. Its return to service has been delayed by almost a year from its original estimated date.

The last planned date for bringing the unit back online was the end of June 2025. Eskom has since remained quiet on any potential return-to-service date.

The main reason for the slight EAF gain is a reduction in planned maintenance. In the first week of May 2025, the planned capacity loss factor (PCLF) was at 14.28%.

By mid-June 2025, that had dropped to just 8.31%, the lowest point of the year so far. At the same time last year, it was able to run at a 11.80% PCLF without needing to implement load-shedding.

While the reduction is part of a deliberate strategy to reduce planned maintenance in the winter, the power utility only has so much room to manoeuvre in this area, or it risks more outages in the future.

The table below compares the EAF, unplanned breakdowns, and planned maintenance in week 24 of 2024 and 2025.

Unplanned outages exceed Eskom’s predicted threshold for load-shedding

Eskom previously said it would not need to implement load-shedding over the winter if its unplanned outages remained below 13,000MW of capacity.

It forecast that 15,000 MW of unplanned outages would lead to stage 2 load-shedding. The UCLF and OCLF have more frequently exceeded that level in recent weeks.

At the time of publication, the power utility’s data portal showed that its weekly UCLF and OCLF stood at more than 14,800 MW for 57% of the time from 11 to 17 June 2025, up from just 21% the week before.

The percentage of time during which the two unplanned outage factors exceeded 15,200MW increased from 9% to 34%.

Despite Eskom’s fleet clearly being in a worse state than last year, the power utility’s latest 52-week outlook is much more positive than the same one from 2024.

The power utility’s saving grace in 2025 could be the reduction in demand of more than 1,000MW — equivalent to one stage of load-shedding.

For example, in week 25 of 2025, Eskom is only expecting residual demand to reach 30,036MW, compared with 31,271MW in the same week last year.

Had the power utility’s electricity demand been similar to last year, it would likely already have needed to implement load-shedding.

The following graph shows Eskom’s average monthly PCLF, UCLF, and OCFL, illustrating that Eskom’s monthly unplanned outages are at their highest level in the past 12 months.