Concentrated solar power (CSP)
Power plants that use mirrors to concentrate direct sunlight onto a receiver, heating a fluid that drives a steam turbine, usually with built-in thermal storage.
CSP converts sunlight to heat and then to electricity in a conventional thermal power cycle. Unlike PV it uses only direct beam radiation, so it requires high DNI, typically above 1,900–2,000 kWh/m²/yr.
- Parabolic trough: curved mirrors focus light on a receiver tube carrying synthetic oil at up to about 390 °C; the most deployed design.
- Solar tower: thousands of heliostats focus onto a central receiver, heating molten salt to about 565 °C, giving higher cycle efficiency and cheaper storage.
- Linear Fresnel and parabolic dish: niche designs.
The key advantage is thermal energy storage: molten nitrate salt tanks store heat for 6–15 hours, letting plants generate after sunset and making CSP dispatchable. Plants with large storage can reach capacity factors of 40–60%.
Global capacity was about 7 GW in 2023 (IRENA), concentrated in Spain, the US, Morocco (Noor Ouarzazate, 580 MW), South Africa, China, Chile and the UAE (Noor Energy 1 in Dubai, 700 MW of CSP). IRENA reports that the global weighted-average LCOE fell from about 0.39 USD/kWh in 2010 to roughly 0.12 USD/kWh in 2023. Growth has nonetheless been slow because PV plus battery storage has become cheaper for most applications; CSP retains a niche for long-duration storage and high-temperature industrial heat.
Related terms
All terms →- DNI (Direct Normal Irradiance)
Solar radiation arriving in a straight line from the sun disc, measured on a surface held perpendicular to the sun rays.
- Thermal energy storage
Storing energy as heat or cold, in sensible, latent (phase-change) or thermochemical form, for later use as heat or for power generation.
- Dispatchable generation
Generation whose output can be scheduled, raised or lowered on request by the operator, independently of weather.
- LCOE (Levelized Cost of Electricity)
The constant price per MWh that recovers all lifetime costs of a power plant, discounted to present value, divided by its discounted lifetime output.
- Solar thermal collector
A device that absorbs sunlight and transfers the heat to a fluid, mainly for domestic hot water, space heating, district heating and industrial process heat.
- Solar tracker
A motorised mounting structure that rotates PV modules or mirrors to follow the sun, raising the irradiance they receive over the day.