Energy characterization of an unglazed pv/t panel for the production of electricity, heating and cooling

In this work the possibility of using unglazed PV/T solar systems for the daytime production of electricity and heat, and cooling energy during night, has been considered. The diurnal refrigeration increases the electric efficiency of the photovoltaic cells and it makes thermal energy available; while at night the panel exploits the radiative cooling of the sky to produce a cooled water flow rate at a lower temperature than the outside air. By means of a physical model of a modified PV/T collector implemented in a computer code, the bi-directional distribution of temperature in the absorber plate has been considered. The collection system has been sized in order to favour the production of electrical power. An investigation on the PV/T panel in order to evaluate the variability of the of heat loss coefficient in function of the absorber temperature has been developed. Subsequently, the electric, thermal and cooling efficiencies in function of the main characteristic parameters of the panel have been determined.