Performance Improvement Optimisation of a Photovoltaic System located at the Tropical Climate using Water-Film Cooling Method

The temperature rise of solar panels can cause significant reduction in the energy generation especially for the countries located in tropical climate region. It is more effective to use water-film for cooling the front surface of solar panels, but the energy consumption of the water-cooled photovoltaic system (WCPV) needs to be reduced to obtain a higher net energy gain. In this study, a discrete water-supply water-cooling system (D-WCPV) has been proposed to reduce the energy consumption of the water pump and to improve the performance of a retrofit or building integrated photovoltaic system through reduction of the panel temperature. The discrete mechanism utilises a relay to switch on the power supply of the water pump whenever the temperature of the solar panel has reached the threshold of 45 °C. It is found that minimum flow rate for the D-WCPV is 8 L/min to form a full coverage of water on the surface of the solar panel for providing an uniform cooling effect and hence providing a better performance improvement. A comparison has also been made for the continuous water-supply water-cooling system (C-WCPV) and D-WCPV. D-WCPV has two advantages over C-WCPV as follows: 1) the energy consumption of the water pump operating at flow rate of 8 L/min has been reduced by 86.7% from 0.057 kWh/h to 0.0076 kWh/h and (2) the net energy gain (NEG) of the system at solar irradiation ranging from 806 Wh/m² to 950 Wh/m² has been increased by 80.2% from 5.5% to 10.0%.