An Experimental Study on a Photovoltaic/Thermal (PV/T) Air Collector with Direct Coupling of Fans and Panels

A photovoltaic/thermal air collector is designed, built, and tested at a geographic location of Kerman, Iran. In this system, photovoltaic panels are directly used to power the fans. Therefore, during a day, air mass flow rate and its related parameters change with variation of solar radiation and ambient temperature. A thin metal sheet is used to improve heat extraction from the panels and, consequently, achieving higher thermal and electrical output. The metal sheet is suspended at the middle of a photovoltaic/thermal system air channel. This photovoltaic/thermal system is tested in natural convection and forced convection (with two, four, and eight fans operating) and its unsteady results are presented with and without glass cover cases. It is seen that in the case of forced convection, air mass flow rate decreases by installing a glass cover on photovoltaic panels. On the contrary, in free convection mode, installing a glass cover leads to an air mass flow rate increase. Also, results show that setting a glass cover on photovoltaic panels leads to an increase in thermal efficiency and a decrease in electrical efficiency of the system. Additionally, it is concluded that in the studied system, there is an optimum number of fans for achieving maximum electrical efficiency.