New R11.6-billion solar project likely to be SA’s last CSP

The Redstone CSP plant South Africa final solar project has officially reached full commercial operation, marking a historic moment in the country’s renewable energy development. This R11.6-billion 100MW concentrated solar power (CSP) facility may be the last of its kind to be built in the nation due to rising costs and the shift toward more competitive technologies such as photovoltaic (PV) solar and lithium-ion battery storage.

This Redstone solar power plant — located in the Northern Cape — was once seen as a beacon of innovation, using molten salt thermal storage to provide power even after sunset. Yet its protracted timeline and diminishing economic feasibility signal a turning point for CSP in renewable energy South Africa.

How the Redstone CSP plant works

Unlike traditional PV plants that generate electricity directly from sunlight, CSP facilities like Redstone use mirrors to concentrate solar heat. This heat warms a molten salt thermal battery, which stores energy and generates steam to turn turbines — producing electricity well into the night.

The Redstone CSP plant boasts a 1,200MWh battery that can dispatch 100MW of electricity for up to 12 hours after sunset, overcoming one of solar energy’s biggest limitations. It is the sixth CSP project built under the government’s Renewable Energy Independent Power Producers Programme (REIPPP).

However, the Redstone CSP plant South Africa final solar project may be the last due to high costs, technical challenges, and shifting energy priorities.

Why Redstone is likely the final CSP plant

Despite its technical sophistication, Redstone’s completion in 2024 came nearly a decade after it was first proposed in 2015. Originally selected as a preferred bidder in REIPPP’s Bid Window 3.5, the project faced delays in signing its power purchase agreement (PPA) with Eskom until 2018.

Industry expert Chris Yelland called the project an anomaly, pointing to repeated deadline extensions by the Independent Power Producers’ Office despite unmet financial requirements. “Under normal circumstances, a bid bond would be forfeited for such delays,” Yelland stated.

The Redstone solar power plant was initially developed by US-based SolarReserve, in partnership with Saudi Arabia’s Acwa Power. After SolarReserve’s bankruptcy and the failure of its Crescent Dunes CSP facility in Nevada, Acwa Power took full control and revived the South African project.

CSP’s decline vs. PV’s rise

The Redstone CSP plant South Africa final solar project highlights CSP’s biggest challenges: complexity, high operational cost, and the requirement for co-located thermal storage. CSP mirrors need to be precisely adjusted daily to align with the sun’s ever-shifting position, adding technical burden and cost.

In contrast, photovoltaic plants are simpler, cheaper to build and maintain, and require less manpower. Additionally, lithium-ion battery storage solutions can be installed independently across the grid, increasing flexibility and bypassing geographic constraints.

CSP projects, including Redstone, must be located in sun-rich desert areas like South Africa’s Northern Cape — which unfortunately now suffers from transmission grid saturation, further limiting CSP viability.

PV and battery projects are outpacing CSP

The Redstone plant currently sells electricity to Eskom at R1.223 per kWh under a 20-year PPA. While competitive during its initial bid period, the current reality has shifted. PV plants now offer significantly cheaper generation.

For comparison, the Scatec Kenhardt hybrid project — combining PV with 1,140MWh of lithium-ion battery storage — sells electricity at R1.885/kWh. Though higher, this figure reflects 24/7 dispatchable power and faster project completion — within 3.5 years from bid to operation, compared to Redstone’s six-year build period.

Meanwhile, average prices for PV modules have plummeted from $280 to $111 per kW, and lithium-ion battery prices have dropped by 39% globally, according to BloombergNEF. These trends are driving the transition away from CSP.

Grid-friendly, scalable, and future-ready tech

One of CSP’s few advantages — integrated thermal storage — is increasingly being outshined by flexible lithium-ion systems. Unlike CSP batteries, which must be physically attached to the plant, modern batteries can be deployed anywhere in the grid.

This decoupling supports improved energy distribution, voltage regulation, and transformer load balancing — crucial as South Africa works to stabilise its fragile grid. Yelland notes that decentralised storage is the future of dispatchable renewable power.

With the Redstone CSP plant South Africa final solar project completed, the country is now clearly pivoting towards PV, battery, and wind energy projects for cost-effectiveness, scalability, and speed.

The legacy of Redstone and the road ahead

Although Redstone may mark the end of CSP in South Africa, it leaves behind a legacy of innovation and learning. It proved that renewable energy South Africa can offer baseload support through alternative solar technologies. Yet it also exposed the risks of betting on emerging, complex, and capital-intensive systems in an evolving energy market.

As PV and battery storage continue to mature, future projects are expected to be faster to deploy, cheaper to operate, and better suited to South Africa’s grid realities and economic constraints.

In closing, the Redstone CSP plant South Africa final solar project represents both a remarkable engineering feat and a cautionary tale. As the energy sector adapts, one message is clear: the next chapter in renewable energy South Africa will be written by simpler, cheaper, and more scalable technologies — and CSP likely won’t be part of it.

Here are five mainstream South African media references that have covered the Redstone CSP plant or broader topics such as renewable energy, CSP, and Eskom’s power procurement:

1. MyBroadband
   “Redstone solar power plant officially begins operations — one of South Africa’s most advanced”
   This article discusses the commissioning of the Redstone CSP plant and includes expert commentary from Chris Yelland.
   🔗 https://mybroadband.co.za/news/energy/525416-redstone-solar-power-plant-officially-begins-operations-one-of-south-africas-most-advanced.html

2. News24
   “Redstone CSP plant starts operations after years of delays”
   Covers the background of the Redstone project and details around its completion and cost.
   🔗 https://www.news24.com/fin24/economy/redstone-csp-plant-starts-operations-after-years-of-delays-20240624

3. Engineering News
   “Redstone CSP plant reaches commercial operation”
   Industry-specific reporting on the technical specifications and implications for South Africa’s energy mix.
   🔗 https://www.engineeringnews.co.za/article/redstone-csp-plant-reaches-commercial-operation-2024-06-25

4. Daily Maverick
   “Renewable energy shake-up: Why PV and batteries are overtaking CSP”
   In-depth analysis of why concentrated solar power is falling out of favour in South Africa.
   🔗 https://www.dailymaverick.co.za/article/2024-07-02-renewable-energy-shake-up-why-pv-and-batteries-are-overtaking-csp

5. Business Day (BDLive)
   “Eskom and the end of CSP: What Redstone tells us about energy policy”
   Opinion and business analysis regarding the policy shift away from CSP in South Africa.
   🔗 https://www.businesslive.co.za/bd/opinion/2024-06-26-eskom-and-the-end-of-csp-what-redstone-tells-us-about-energy-policy/