South Africans with solar power give Eskom a kick in the teeth

The latest data from the National Transmission Company of South Africa (NTCSA) shows substantial growth of behind-the-meter rooftop solar power at homes and businesses over the last year.

In its latest system status outlook, the NTCSA estimated the combined capacity of these systems reached 8,294 megawatts (MW) in May 2026.

That reflected an increase of about 1,944MW — or 30.6% — from the 6,350MW installed in the same month last year.

Since the NTCSA started estimating rooftop solar capacity in July 2022, less than four years ago, the capacity has increased by more than 6,000MW — or 265%.

The total capacity in May 2026 is 385MW more than the combined renewable energy capacity feeding power into Eskom’s grid, which was roughly 7,909MW.

Gauteng has continued to lead the country with 2,247MW of behind-the-meter solar power, an increase of roughly 310MW over the last year.

The biggest growth over the last 12 months was in the Northern Cape, where estimated capacity more than doubled from 335MW to 758MW.

Other provinces which recorded a substantial increase in solar power adoption included the Free State and KwaZulu-Natal.

It should be noted that the behind-the-meter capacity only considers systems with individual capacities under 100kWp.

According to the South African Photovoltaic Industry Association, the National Energy Regulator of South Africa has registered over 19,300MW of private generation since 2018.

Over 90% of that capacity was registered between 2022 and the first quarter of 2026, a surge attributed to President Cyril Ramaphosa scrapping the requirement for generators to get a licence from Nersa.

The table below shows the estimated behind-the-meter rooftop solar power installed across South Africa’s nine provinces in May 2025 and May 2026.

Denting Eskom’s sales while taking off the pressure

The increase in private electricity generation has knocked Eskom’s electricity sales in the last five years, contributing significantly to its ability to keep the lights on for most of 2025 and 2026.

While Eskom has frequently highlighted its improvement in energy availability factor (EAF) since 2023 as the main contributor to the reduction in load-shedding, the figure remains below global utility standards.

At roughly 65%, it is at about the same level as in 2020, when Eskom still had to implement significant amounts of load-shedding. Therefore, the decline in demand has been a pivotal factor.

Over the entire 2025 calendar year, Eskom’s annual residual energy demand was 191,377 gigawatt-hours (GWh), 9.7% lower than in 2021.

That was even though the country had nearly no load-shedding in 2025 and 2,416GWh of power cuts in 2021.

The decline has accelerated in 2026. In the first 24 weeks of the year, Eskom recorded residual energy demand of 80,487GWh, a 16.2% decline over the same period in 2021.

On average, Eskom’s hourly electricity demand in 2026 has been 20,325MW, compared with 24,283MW over the same period in 2021.

That means Eskom’s average electricity demand has declined by 3,958MW, roughly equivalent to the power it sheds from the grid in four stages of load-shedding.

Solar power has also played a significant role in helping Eskom reduce its reliance on peaking power plants, including expensive open-cycle gas turbine (OCGT) generation.

Former NTCSA general manager Isabel Fick explained that midday solar power took strain off Eskom generation, allowing it to replenish diesel levels at OCGTs and water levels at pumped-storage schemes.

During the country’s worst years of load-shedding between 2021 and 2023, these plants often needed to run outside of peak hours, when they are intended to be used.

Thanks to solar power, emergency generation levels can be sustained at sufficient levels to supply power during the evening and morning peak demand periods.

In addition, many households and businesses have paired their systems with batteries, which they can use to reduce electricity consumption overnight.

The adoption has been spurred not only by Eskom’s inability to supply reliable power for many years, but also by its above-inflation tariff increases.

While Eskom has increased its average tariff by more than 1,100% since 2007, the cost of solar panels and batteries has plummeted by more than 90%.

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