Updated September 2026.
Concentrated solar power (CSP) doesn’t use solar panels. It uses mirrors to focus sunlight onto a receiver, heating a fluid to several hundred degrees, and that heat drives an ordinary steam turbine. Its big selling point is storage: heat is much cheaper to store than electricity, so a CSP plant with a tank of molten salt can keep generating long after sunset.
The main designs
- Parabolic troughs. These are long curved mirrors that focus light onto a pipe of oil or salt. It’s the oldest and most common design. California’s SEGS plants have run since the 1980s.
- Power towers. Thousands of flat mirrors (heliostats) aim at a receiver on top of a tower, reaching higher temperatures. Examples include Chile’s Cerro Dominador, with 17.5 hours of storage, and Morocco’s Noor III.
- Linear Fresnel and dish systems are less common variations.
Storage: CSP’s real advantage
Most modern CSP plants store heat in molten salt, typically a mix of sodium and potassium nitrate. They pump it from a “cold” tank at about 290 °C through the receiver to a “hot” tank at about 565 °C, then draw on the hot salt to make steam whenever power is needed. That lets a plant deliver solar electricity through the evening peak, or even around the clock.
Why it has fallen behind
Ten years ago CSP looked like it could become a major source of power. Instead it stalled at around 7 GW worldwide, a tiny fraction of the more than 2,000 GW of solar panels. The reasons:
- Cheap panels plus cheap batteries. Solar panels and lithium batteries fell in price much faster, and together they now do much of what CSP promised, usually for less.
- Complexity. These are large thermal power plants with many moving parts, and several US plants struggled. Nevada’s Crescent Dunes had repeated problems with its salt tank, and California’s Ivanpah agreed in 2025 to close two of its three units early.
- Site limits. CSP needs strong, direct sunlight and clear skies, such as deserts, and it can’t use the diffuse light that panels can.
Where it still makes sense
- Long-duration storage of 10 hours or more, where it can beat batteries on cost. China, Chile, Morocco and the Middle East are still building it for this reason, often alongside large PV plants.
- Industrial heat. Many factories need heat rather than electricity. Using concentrated sunlight directly skips the conversion losses.
- Next-generation designs. Research, including US national lab work on “Gen3” CSP, is testing falling ceramic-particle receivers and supercritical CO₂ turbines. These run hotter and more efficiently, and could lower costs.
Related: Desert Power and 247Solar.
