Concentrated solar power: Techniques
Troughs, towers, Fresnel rows and Stirling dishes compared
What this tab covers The methods used to capture this energy: how each works, and how they compare on efficiency, cost, life-cycle emissions, maturity and scale.Troughs built the first wave of plants; towers with molten-salt storage dominate new construction, mostly in China. CSP costs about two and a half times as much as PV per MWh but can deliver power after sunset.
Comparison
| Method | Efficiency | Cost | Life-cycle emissions | Maturity | Scale |
|---|---|---|---|---|---|
| Parabolic troughs1234 | 14-16% annual; capacity factor up to about 40% with 7.5 hours of storage | All-CSP average USD 115/MWh and USD 2,418/kW (2025) | Published median 26 g CO2e/kWh | mature | Part of 7.2 GW of CSP worldwide (end-2024) |
| Power towers with heliostats143 | About 16% annual; capacity factor 68-79% with 12-15 hours of storage | Recent Chinese towers CNY 16,000-16,200/kW (about USD 2,222-2,251/kW); Redstone, South Africa, about USD 7,360/kW | Published median 38 g CO2e/kWh | mature | Most of about 3.3 GW under construction in China; the 386 MW Ivanpah plant (no storage) is slated to close in 2026 |
| Linear Fresnel reflectors14 | 11-13% annual | No separate figure in the sources used | No harmonised figure | early commercial | Largest is 100 MW at Yumen, Gansu (operating since 2024) |
| Stirling dishes1 | 25-30% | No commercial price | No harmonised figure | pilot | No significant fleet |
| Solar updraft towers (experimental)9 | Very low; no figure in the sources used | No commercial cost | No figure | research | A 50 kW prototype at Manzanares, Spain, ran for seven years |
CSP's 2025 LCOE of USD 115/MWh is about 2.6 times PV's USD 44/MWh, and its cost per kW about 3.6 times higher (both calculated), because mirrors, towers and turbines are heavy engineering in a small market. Buyers pay for storage: a tower with 10-15 hours of salt serves the evening peak. Life-cycle emissions (26-38 g CO2e/kWh) are similar to or below silicon PV.
How each method works
Parabolic troughsCurved mirrors track the sun on one axis and focus it on an oil-filled tube heated to about 390 C, which raises steam for a turbine; some heat can be stored in molten salt.1234
Power towers with heliostatsThousands of two-axis mirrors reflect sunlight onto a receiver atop a tower; molten salt at about 565 C is stored in a hot tank and drawn off to raise steam when needed.143
Linear Fresnel reflectorsRows of nearly flat mirrors focus sunlight on a fixed pipe above them, boiling water directly into steam.14
Stirling dishesA dish mirror focuses sunlight on a Stirling engine at its focal point, which drives a generator directly.1
Solar updraft towers (experimental)A large glass roof warms air, which rises up a tall chimney through wind turbines; no concentration, so diffuse light also counts.9
Sources
- Concentrating Solar Power: Technology Brief E10 IRENA and IEA-ETSAP, 2013
- Renewable Power Generation Costs in 2025 (Executive summary, Figure S1) IRENA, 2026
- Life Cycle Greenhouse Gas Emissions of Trough and Tower Concentrating Solar Power Electricity Generation: Systematic Review and Harmonization (Burkhardt et al., Journal of Industrial Ecology 16 S1, S93-S109) NREL LCA Harmonization Project / RePEc, 2012
- Renewables 2025 Global Status Report: Concentrating solar thermal power REN21, 2025
- Solar chimney pilot plant Manzanares schlaich bergermann partner (designers of the prototype), 2024