An experimental study on using water streaks and water film over PV module to enhance the electrical efficiency

Since the solar irradiation is accessible in many parts of our planet, it is a viable replacement for fossil fuels, so commissioning photovoltaic (PV) power plants are increased, rapidly. One of the main problems that this technology faces is the increase in the temperature of solar cells. In this paper, streaming water layer over the upper side of PV modules is considered as a cooling method. This technique not only lowers the surface temperature, but also keeps the surface clean. Four different water flow rates of 0.5, 1, 2, and 4 lit/min were used so that two different flow patterns, water streaks and water film, were formed. In addition, the negative effect of the residual water layer over the surface of the PV panel on the absorbed radiation was evaluated experimentally. As results, temperature drops of 20.6 °C and 29.7 °C were measured for flow rates of 0.5 and 2 lit/min, respectively. Also, for the case of 4 lit/min, the efficiency is increased by 6.7% compared to the conventional case. Moreover, it was observed that after the formation of a water layer, the water flow rate no longer has a significant effect on cooling. Finally, a comparison between the electrical efficiency enhancements of this study with those of similar researches was performed.