Experiment and model of a photovoltaic module with evaporative cooling

Most studies on evaporative cooling of photovoltaic modules have primarily relied on experimental investigations without any general model to investigate the module performance. In this paper, an experimental model similar to that of solar collector performance was developed in terms of total efficiency and ratio of temperature difference between cooling fluid and ambient temperatures with solar radiation for finding the module thermal characteristics which were optical efficiency and module overall heat loss coefficient, the module temperature, and then the generated electrical power. To validate the model, experimental tests were conducted on a 320 Wp monocrystalline photovoltaic module of 1.956 m × 0.992 m area equipped with an evaporating surface at the module rear surface on some clear sky and cloudy days in Chiang Mai, Thailand. The evaporating pad was made of cellulose and polypropylene with 5 mm thickness. A controlled flow rate of water at 0.3 L/min was maintained with inlet temperatures ranging between 25 and 35 °C, ensuring a non-dripping condition. The results from the new simplified model demonstrated good agreement with the experimental data. In addition, the developed model was also used to predict the yearly performance of the photovoltaic module with evaporative cooling under tropical climate of Chiang Mai. The average total and net monthly electrical output were increased 7.04 and 4.47%, respectively compared to that of the normal unit. In case of hot and arid area such as Ouargla, Algeria, better improvement of PV module performance could be attained, and the average total and net monthly power generation could be enhanced 8.62 and 6.48%, respectively.