Eskom Maintains Grid Stability Ahead of Cold Week, Plans 2,550MW Capacity Boost

Eskom reports that South Africa's power system remains stable despite occasional constraints as the country heads into a forecasted cold spell next week. The utility plans to add 2,550MW of generation capacity ahead of Monday evening's peak demand to bolster grid resilience.

System Performance Improving After Maintenance

The national grid is showing signs of recovery as Eskom moves beyond its peak maintenance season. The Planned Capability Loss Factor (PCLF) has decreased from last week's average of approximately 4,883MW to this week's average of 4,035MW (30 May to 5 June).

As a result, the Energy Availability Factor (EAF) has been fluctuating between 61% and 64% since Monday, with the month-to-date figure standing at 60.42%. This improvement reflects the successful return of generation units from planned maintenance.

For the financial year-to-date, planned maintenance has averaged 5,974MW, representing 12.76% of total generation capacity. While this shows a decrease from the previous week, it represents a 2.1% increase compared to the same period last year.

Unplanned Outages Remain Above Target

The Unplanned Capacity Loss Factor (UCLF), which measures capacity lost due to unplanned outages, stands at 28.93% for the financial year to date (1 April to 5 June 2025). This is a slight increase of approximately 0.8% compared to 28.17% recorded over the same period last year.

From 30 May to 5 June 2025, unplanned outages averaged 14,644MW, representing an increase of 2,315MW compared to the same period last year and 1,644MW above Eskom's base case of 13,000MW. For the financial year to date, average unplanned outages stand at 13,760MW.

A significant contributor to this week's higher unplanned outages is the delayed return of Medupi Unit 4. This 800MW unit is in the final stages of a long-term recovery project following generator damages from August 2021. Commissioning activities are currently underway with Grid Code compliance testing expected to resume next week. The unit is anticipated to return to service within June 2025.

Diesel Usage Decreasing

The Open-Cycle Gas Turbine (OCGT) load factor decreased to 6.31% this week, compared to 12.70% in the previous week (23 to 29 May 2025), indicating reduced reliance on diesel. The financial year-to-date OCGT load factor shows a 5.2% decrease compared to the previous week.

Year-to-date, Eskom has spent approximately R3.76 billion on fuel for the OCGT fleet, generating 631.52GWh. This is higher than the 246.91GWh generated during the same period last year.

The diesel expenditure remains within budget for the current financial year, with usage expected to decline further as more units return from long-term repairs and maintenance activities are reduced.

Current Status and Capacity

As of today, unplanned outages amount to 13,855MW, while available generation capacity stands at 28,875MW (excluding the 720MW capacity generated by Kusile Unit 6, which is still progressing toward commercial operation). Tonight's peak demand is projected to reach 28,344MW.

Outlook for Winter

Eskom's Winter Outlook, published on 5 May 2025 for the period ending 31 August 2025, remains unchanged. It indicates that loadshedding will not be necessary if unplanned outages stay below 13,000MW. If outages rise to 15,000MW, loadshedding would be limited to a maximum of 21 days out of 153 days and restricted to Stage 2.

Given that current unplanned outages stand at 13,855MW, slightly above the 13,000MW threshold, the system remains vulnerable to unexpected breakdowns, especially during the approaching cold spell.

Warning Against Illegal Connections

With electricity demand rising during winter, Eskom has warned against illegal connections and energy theft, which often lead to transformer overloads, equipment failures, and in some cases, explosions and extended outages. These situations sometimes necessitate load reduction to protect the network.

Eskom encourages customers to purchase electricity only from accredited vendors and urges eligible households to register for free basic electricity with their local municipalities.

Key Terms Explained

• Energy Availability Factor (EAF): The percentage of maximum energy generation that a plant is capable of supplying to the electrical grid, accounting for both planned and unplanned outages. A higher EAF means more of the country's installed capacity is available for use.
• Planned Capability Loss Factor (PCLF): The percentage of energy generation lost due to planned maintenance. This is necessary work to keep power stations functioning well in the long term.
• Unplanned Capacity Loss Factor (UCLF): The percentage of energy generation lost due to unexpected breakdowns and failures. This is a key indicator of system health – lower is better.
• Open-Cycle Gas Turbines (OCGTs): Emergency power generation units that run on diesel fuel. They're expensive to operate (about 4-5 times more costly than coal generation) but can be started quickly during peak demand or emergencies.
• Megawatt (MW): A unit of power. As a general reference, 1MW can power approximately 650 average South African homes.
• Gigawatt-hour (GWh): A unit of energy equal to one gigawatt of power sustained for one hour. For context, South Africa typically consumes around 30,000 GWh of electricity per month.