Tornado-like wind speeds took out parts of big South African solar plant

Karoshoek Solar One’s 100MW Ilanga concentrating solar plant (CSP) is back in operation and producing around 87% of the plant’s expected output after freak weather destroyed portions of the plant on Saturday, 8 March 2025.

Energy expert Chris Yelland shared footage of the storm and the damage it caused. Karoshoek Solar has confirmed that the storm only destroyed portions of the plant.

“Sunday, 8 March 2025: The morning started completely overcast, but a break in the cloud cover at 10:27 allowed Ilanga CSP1 to synchronise to the grid at 12:49,” it said in a statement.

However, it noted that complete cloud cover returned less than an hour later, and the solar field was set to its stow position at 14:02 to protect it from high winds.

“At 14:36, the Southern side of the solar field (subfields 8, 10, and 11) was subjected to severe, uncommon, localised wind speeds,” said Karoshoek Solar One.

“The Southeast weather station registered a maximum wind speed of 40.9 metres per second.”

According to the UK’s Tornado and Storm Research Organisation, wind speeds of between 33 and 41 metres per second are similar to the winds produced by moderate tornados.

It noted that the solar field was designed to withstand a maximum wind speed of 31 metres per second.

“The incident led to the breakage of a number of mirrors, punched arms (to which the mirrors are attached) and receiver tubes in subfields 8, 10, and 11,” it added.

The company also provided information on its isolation of the subfields on Sunday, 9 March, and its inspection of the damages on Monday, 10 March.

“A high-level inspection of the solar field and power block was conducted by the Ilanga CSP1 and Operator teams to ascertain the extent of the damage,” it said.

Karoshoek noted that most of Sunday the 9th was overcast, meaning minimal production losses were suffered due to the inspection activities.

The solar field, excluding subfields 8, 10, and 11, was inspected on Monday, 10 March, and deemed safe enough to resume operation.

“The Ilanga CSP1 was ramped up accordingly, and the plant managed to produce 73% of the Facility Power Model’s expected output for the data,” it said.

On Tuesday, 11 March, the plant produced 87% of its expected output for the day.

“The plant has been operating and feeding electricity to the grid since Tuesday,” Karoshoek Solar One added.

According to Karoshoek Solar One board chair Tshepo Rachidi, work is underway to restore the damaged subfields to operation as soon as possible.

The Karoshoek Solar One project began commercial operation in November 2018. It has a storage capacity of 500MWh and cost around R11 billion to complete.

Unlike traditional solar plants that use photovoltaic cells to produce energy, Ilanga, a CSP, uses parabolic mirrors to concentrate sun rays towards a receiver, or power block, to generate heat.

The heat drives a heat engine connected to an electrical power generator or powers a thermochemical reaction that produces energy.

Yelland shared video footage of the storm and the damage it caused on Tuesday, 11 March 2025.

“The damaged plant in the video is the 100MW Ilanga CSP with 500 MWh storage, situated in the Upington area,” he said.