Concentrating solar collectors use mirrors or lenses to focus sunlight onto a small absorber surface, achieving much higher temperatures than flat or evacuated tube collectors. These systems concentrate solar radiation by factors of 10 to 1,000 times, enabling temperatures suitable for industrial processes, thermal storage, and electricity generation.
Types and Applications
Common concentrating designs include parabolic troughs, solar towers, and Fresnel reflectors. Parabolic troughs concentrate sunlight along a linear focus achieving 400°C temperatures. Solar towers use heliostats to focus light on a central receiver reaching 500-800°C. These systems require direct beam radiation and cannot use diffuse light from clouds, limiting use to regions with high direct normal irradiance values. They demand precision tracking systems and higher maintenance than non-concentrating collectors.
Performance Characteristics
Concentrating collectors achieve thermal efficiencies of 60-75% in industrial applications. They concentrate heat into small receiving areas where minimal convective losses occur, enabling higher outlet temperatures than conventional thermal collectors. Cost and complexity increase with concentration ratios. Applications include commercial steam generation, district heating, thermal energy storage, and concentrated photovoltaic systems where concentrated light drives high-efficiency photovoltaic cells.