Concentrated thermal solar power plants (CSP) are used as a renewable source of heat energy or electrical energy. CSP systems focus the sun rays falling on a large area into a single small area by means of mirrors and sun tracking systems connected to these mirrors. The concentrated sunlight is then used to generate the required heat in the orc system. In addition, the generated heat energy can be used for other purposes.

Parabolic troughs work by having parabolic (pit-shaped) reflectors collect sunlight in a receiver placed at the focal point of the reflectors. The receiver here consists of a tube extending in the direction of the focal points of the reflectors and containing the circulating fluid. The reflector follows the sun with tracking mechanisms throughout the day. The circulating fluid heats up around 150-300 °C as it moves through the receiver. It is then used in the power generation plant as a source of heat energy. Parabolic trough systems are the most advanced among CSP technologies.