Efficient stationary solar thermal collector systems operating at a medium-temperature range

In this paper, a stationary solar thermal collector system using an evacuated glass and a counter-flow tube for medium is modeled, analyzed, fabricated, and tested. The proposed non-tracking system consists of an evacuated counter-flow type absorber paired with an external compound parabolic concentrators (XCPC) as a non-imaging reflector. This configuration allows the system to operate with a high solar thermal efficiency for medium working temperature (100–300 °C). Efficiencies for both East–West and North–South orientations are modeled and measured at various working temperatures. Simulation and experimental test results show that the proposed configuration outperforms other non-tracking solar thermal systems and can achieve more than 40% efficiency above 200 °C.