Performance investigation of transparent photovoltaic-thermal collector with horizontal oscillating and rectangular spiral flow patterns

Efficiency drop due to increase in photovoltaic (PV) module operating temperature creates a huge difference between the projected and actual electricity generated in large power plants. As a solution to this problem Photovoltaic-Thermal (PV/T) collector, with PV at top and thermal collector at the bottom has been developed. PV/T can cool the PV as well as generate low-temperature thermal energy. This article presents a comparative experimental study of two newly developed PV/T collector having transparent solar panel with copper tube absorber arranged in rectangular spiral (PV/T-RS) and horizontal oscillating (PV/T-HO) configurations. The PV/T collectors are experimentally evaluated under outdoor conditions at Indian Institute of Technology Guwahati. The developed PV/T's are compared in terms of electrical and thermal efficiencies. The PV/T-RS is found to be better as compared to PV/T-HO in terms of electrical output, whereas reverse result is reported in case of thermal output. The average electrical and thermal efficiency was found to be 11.2% +/- 0.95% and 57.11% +/- 2.94% for PV/T-RS. The calculated average thermal efficiency of PV/T-HO (63.6% +/- 2.94%) is found to be 11.4% more as compared to PV/T-RS. The overall exergetic efficiency for PV/T-RS and PV/T-HO was found to be in the range 11.8%-16.2% +/- 3.18% and 9.7%-15.25% +/- 3.18%, respectively.