Measuring energy efficiency from a 4 kW dish concentrator system using older parabolic antenna technology

A fiberglass parabolic dish with a diameter of 2.44 m and focal length of 0.92 m, used for telecommunication in decades past, has been converted into a parabolic solar concentrator. In previous work a solar tracking system was developed and a vinyl-aluminum film was applied to the receiver to make it reflective. Current studies began with the analysis of the optical properties of the vinyl-aluminum film after three years of exposure to the elements; subsequently a new film was tested and applied. A receptor, serving as a heat exchanger, was constructed from carbon steel in order to measure the energy efficiency and net energy gain of the system. A cost analysis is reported for the entire system. The average net energy gain for the 4.68 m² receiver was 2.18 kJ when normal direct irradiance averaged 950 W/m². With thermal efficiency measured to be 48%, capable of reaching 53%, a Stirling engine is proposed to generate electricity.