Eskom has a new enemy

The latest estimates from the National Transmission Company of South Africa (NTCSA) show the peak generating capacity of private solar power has surged by more than a third from a year ago.

According to the NTCSA’s system status update for the 29th week of 2026, South Africa’s estimated behind-the-meter rooftop solar power capacity reached 9,107.4MW in June 2026.

That reflects a 35% increase over the 6,799.7MW installed in June 2025 and a 18% expansion in half a year.

To put the capacity into perspective, one can compare it with that of Eskom’s largest coal-fired power stations — Medupi and Kusile — which can each supply up to 4,800MW.

That meant the total estimated rooftop solar capacity installed for private use in South Africa is just 500MW short of the combined power of these stations.

Households and businesses were able to roll out this capacity at a much faster rate than Eskom built its last two power stations, which took nearly two decades.

When Eskom first began publishing rooftop solar capacity in South Africa in July 2022, it estimated there was roughly 2,264.5MW spread across the country.

Worsening load-shedding spurred an acceleration in adoption, with another 2,147MW added by July 2023, bringing the total estimated capacity to 4,740.4MW.

The market slowed slightly in the second half of 2023 and for most of 2024, as most households that could afford to invest in solar and batteries had already done so.

The near elimination of load-shedding in 2024 also choked adoption. However, another major motivator for self-generation would reinvigorate sales from around mid-2025.

Solar equipment and lithium-ion battery prices had dropped to a level where users would be able to recover the cost of their system in electricity savings in a much shorter time than in the past.

Shortening the return on investment period further was Eskom’s continued above-inflation tariff increases.

Estimated rooftop solar power installed in South Africa

The surge in self-generation reduced demand for Eskom’s power significantly, helping the power utility to keep the lights on.

Between 2022 and 2023, Eskom’s total energy demand dropped by 1.9%. That was followed by another 2.9% decline in 2024 and a 4.9% dip in 2025.

In the first 29 weeks of 2026, Eskom measured 98,840GWh of residual energy demand, down 9.1% from last year and 15.6% from the same period in 2022.

At the same time, Eskom has improved the performance of its fleet substantially during the last two years.

In week 29 of 2026, it reached a major milestone — an average weekly energy availability factor (EAF) exceeding 75%.

In the year-to-date, the average EAF was 67.13%, nearly five percentage points higher than over the same period in 2025.

In the past week, Eskom’s operating reserve margin at peak demand — the percentage of excess capacity available as a proportion of demand — was between 24.8% and 62.1%.

This was far from ideal, as it meant Eskom had substantial energy available to sell that was not being bought.

In an attempt to push up its sales, the power utility plans to expand its negotiated pricing agreements (NPAs) with large electricity users.

However, many of these customers, including mines, have already invested substantial sums in self-generating capacity to reduce their operating costs.

The outlook is bleak, not only for Eskom but also for lower-income customers who cannot afford self-generation.

As Eskom loses customers to self-generating solar power, its revenue declines. At the same time, its operating costs have surged, and it appears unable or unwilling to bring these under control.

Unless it regains customers at a rapid pace or slashes its costs, it will have to continue increasing prices, which will be levied on an ever-dwindling customer base.

Experts have cautioned that many would likely resort to illegal connections or meter bypassing to survive financially. This is what three of Eskom’s former CEOs have referred to as a “death spiral.”

The cycle of price increases and sales declines poses a real and existential threat to the utility, unless Eskom fundamentally changes its way of doing business.

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