Experimental study of performance of Photovoltaic-Thermal Unglazed Transpired Solar Collectors (PV/UTCs): Energy, exergy, and electrical-to-thermal rational approaches

Photovoltaic panel associated with Unglazed Transpired Collector (PV/UTC) can convert solar energy into thermal and electrical energy. In the present paper, a UTC capable of combing with PV panels is designed, constructed and tested at Shahid Bahonar University in Kerman, Iran. The performance of the PV/UTC and UTC systems are evaluated based on the simple first law, first law defined as a function of electrical-to-thermal ratio number, and the second law efficiencies. The obtained results showed that mounting PV panel on the UTC can result in photovoltaic cooling, depending on the mass flow rate value of the air passed through the transpired plate. A critical radiation level based on the useful exergy gain is also presented and it is drawn that the greater number of PV panels would cause a decrease in critical radiation level. Also, the results show that the electrical-to-thermal rational and exergetic analyses are very important to design PV/UTC systems.