Seasonal performances of photovoltaic cooling systems in different weather conditions

Silicon based modules have been installed since the beginning of the commercial development of the PV technology, and still represent an important share of the global PV market. However, they are penalised when cells reach high temperatures, with a worsening of the conversion efficiency due to thermal drift. Several cooling techniques have been proposed to attenuate this drawback, where water- and air-based solutions have proved to be the most effective and applicable, even though issues related to deterioration of front glass optical properties and thermal shock may occur. In order to overcome these limitations, in this paper the authors report the performances of three different cooling systems operating on the PV module back surface over an acquisition period of eight months. Two systems are based on a spray cooling mechanism whereas the third exploits the forced ventilation of a cavity placed under the module. Data were monitored on the experimental set-up located on the building roof of the Department of Mechanical Engineering of University of Calabria (Italy). Results demonstrate the excellent performance of a simple spray cooling system, able to generate a monthly energy increase up to 8.6%, with a global water consumption of 2.78 m3 in the whole analysed period, whereas the employment of more complex systems based on mechanical ventilation proved to be ineffective for cooling applications.