Bokpoort is a 50MW solar plant. The thermal storage provides upto 9 hours of storage and is one of the most efficient solar plants in the world.
The parabolic trough technology operates by tracking the sun with the parabolic reflectors and focusing the sun’s rays into an absorber pipe. The absorber pipe, which is seated above the mirror along the focal line, contains a heat absorbent medium that absorbs the energy.
The heat absorbent material carries energy to water in a boiler heat exchanger and the heat is used to produce steam which drives a turbine.
Refer to this video on the workings of Concentrated Solar Power and Parabolic Through Plants.