A parabolic trough is a concentrating solar collector with a parabolic-shaped reflective surface that focuses sunlight onto a linear receiver tube positioned at the focal line. This design achieves concentration ratios of 70-100 times, generating temperatures between 350°C and 400°C suitable for industrial heat and electricity generation.
Technical Configuration
The parabolic mirror, typically 5-6 meters wide and 100+ meters long, reflects direct sunlight along the length onto an absorber tube containing heat transfer fluid. A tracking system rotates the mirror to follow the sun’s daily path, maintaining optimal concentration. The tube features selective coatings and glass envelopes to minimize radiative losses. Thermal oil commonly circulates through the tube, with inlet temperatures of 300°C and outlet temperatures of 400°C. Single-axis tracking adds complexity but increases annual energy collection by 25-35% compared to fixed installations.
Power Generation and Industrial Use
Parabolic troughs represent the most mature concentrating solar technology with several large-scale power plants operating worldwide. The Ivanpah Solar Electric Generating System in California uses parabolic troughs to generate 377 megawatts. Industrial applications include process heat for chemical production, water desalination, and thermal energy storage. Capital costs range from $2,500 to $4,000 per kilowatt thermal for large installations.