Kathu plant's maintenance outage ensuring long-term efficiency in CSP operations

Kathu Solar Park (KSP), one of South Africa's select few concentrated solar power (CSP) plants, located in the Northern Cape, recently underwent a 30-day offline period to complete its yearly maintenance.

Operational since 2019, KSP’s maintenance this year included a detailed inspection and refurbishment of its steam turbine – a core component that transforms thermal energy into electricity, making it essential to the plant’s functionality.

During the 30-day outage, the primary focus was a full inspection of the steam turbine, involving the dismantling of both high and low-pressure turbine cylinders.

This inspection included removing the last two stages of blades on the low-pressure turbine rotor for nondestructive testing of blade attachments.

Beyond the turbine, the team conducted substantial refurbishment on essential auxiliary systems, including turbine auxiliary systems, electrical maintenance and solar field maintenance that included the replacement of isolation valves to ensure reliable operation of the parabolic trough system.

Siemens Energy, the steam turbine’s original-equipment manufacturer, played a key role in the turbine inspection, bringing specialist skills to ensure the maintenance was completed with precision, says KSP.

Supplementing this expertise, 39 local workers were contracted for additional manpower, covering roles from unskilled to semi-skilled positions.

KSP says these local contractors supported the work scope while receiving rigorous training focused on safety, underscoring its commitment to both operational excellence and local community involvement.

“Unlike more modular solar PV systems, CSP plants like Kathu’s parabolic trough system have integrated components that must work in unison. This means that taking one part offline necessitates a full plant shutdown.

“The maintenance strategy aims to consolidate all necessary tasks into an annual outage, reducing overall downtime. This year’s 30-day outage differed from previous years, as it included major inspections and upgrades not previously required, such as opening the turbine casings and updating control systems for improved reliability,” says KSP technical manager Dr Gary de Klerk.

Among the upgrades completed, the turbine controller and balance-of-plant control system saw software enhancements designed to boost the reliability and efficiency of plant operations.

While these upgrades may not immediately reduce the plant’s environmental footprint, KSP says they contribute to a more reliable power generation system that supports the facility's long-term viability and performance.

The maintenance outage concluded on schedule, with critical tasks completed, including the turbine inspection, which found no issues in the last-stage rotating blade attachments.

Though some minor findings required attention, KSP says the maintenance team managed to address most within the allotted time. Any remaining tasks are scheduled for future maintenance, ensuring Kathu Solar Park continues to operate smoothly and efficiently.

“KSP’s 2024 maintenance reflects the rigorous standards required to sustain a CSP plant, with in-depth turbine inspections, system upgrades, and a comprehensive strategy that supports both operational reliability and local workforce involvement,” says KSP.