The return to service of one of Eskom’s biggest power station units is running almost a year later than planned, complicating the power utility’s plan to end load-shedding for good.

Eskom has recently gone quiet about progress in restoring Medupi Unit 4 to operation, with almost four years of downtime since it suffered a catastrophic explosion.

In early August 2021, the 720 MW unit was taken offline for what was supposed to be a short-term outage for scheduled maintenance.

Employee error led to air mixing with hydrogen

Employee error led to air mixing with hydrogen in the unit’s generator, creating an explosive blend. The blast was so powerful that some residents 10km away in Lephalale thought it was an earthquake.

Energy expert Chris Yelland was the first to publish photos of the wrecked generator and described the damage in bleak detail.

“The ends of the generator have been blown off, the generator is destroyed, and it will have to be replaced,” he said. “This is a massive setback.”

Eskom estimated the cost of the repair would be around R2.5 billion but said that it would be covered under its insurance. Based on its early assessment in the days after the explosion, Eskom initially estimated it would take around two years to repair the unit and bring it back online.

Yelland had recommended that Eskom consider taking an unused generator from Kusile to replace the one damaged at Medupi to speed up the repair time.

The estimated return-to-service date was pushed back by another year to August 2024 after Eskom shared the results of a preliminary investigation into the incident’s cause and the full extent of the damage.

That did not happen, and by October 2024, Eskom confirmed to energy expert Chris Yelland that the return to service had been delayed to March 2025.

However, in early April, Eskom said that the unit would be online only by the middle of that month or early May 2025. A few weeks later, it revised the expected return to service to the end of April or mid-May.

Medupi’s full operation key to ending load-shedding

As of early June 2025, Medupi Unit 4 was still offline. Eskom has also gone completely quiet regarding the unit, instead focusing predominantly on progress at its sister plant, Kusile, in its weekly updates.

The return to service of Medupi Unit 4 is one of two key steps Eskom wants to complete before it will feel comfortable with officially declaring the end of load-shedding.

The other major goal is the 800 MW Kusile Unit 6

The other major goal is the 800 MW Kusile Unit 6 reaching full commercial operation, which is scheduled to take place in the second half of 2025.

However, an energy expert has warned that even if these two units were fully operational and delivering their 1,520 MW of capacity, the country was not out of the woods.

Independent analyst Mohamed Madhi told TechBrunch that even a “semblance of some decent economic growth” would increase power demand and necessitate the return of load-shedding.

He believes an economic expansion of 2% to 3% in 2025 would be enough to necessitate the regular recurrence of the power cuts.

At the time of Madhi’s comments, Investec was expecting the country’s gross domestic product (GDP) to expand by 1.1% to 1.9% in 2025.

However, in what may be a blessing in disguise for Eskom, recent data has led economists and financial institutions to revise South Africa’s expected GDP growth in 2025 to around 1%.

In its latest update, Investec’s estimated GDP growth for 2025 was 1.2%, down from 1.7% in March 2025. For 2026, the forecast has been adjusted from 1.8% to 1.5%.

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