An Experimental Study of Air Cooling for Solar Cells in Building Applications

摘要

Solar photovoltaic (PV) cells have been applied to generate electricity in many countries and regions. Some solar cells are installed into roofs or walls of buildings to form building integrated PV (BIPV) systems. Applications of BIPV systems can benefit the urban environment significantly. Majority of solar cells are made of silicon and performance of crystalline silicon solar cells are dependent on temperature. Power of a PV system can drop remarkably in summer when the solar irradiance is strong. It is very important to reduce the temperature of BIPV systems to improve the efficiency of electricity generation. In this paper, temperatures of PV panels with different air cooling methods have been measured. Output powers of PV systems have been evaluated based on the net output power. The temperatures of solar panels with an air channel on their backsides are higher than those of regular addon solar panels. Nevertheless, the temperatures of solar panels naturally cooled on the backside are lower than those without any air cooling on the hack side. The temperature difference can reach around 7 ℃ when the solar radiation intensity is strong. Forced air cooling can further reduce the temperature of solar panels, which is usually below 50 ℃ at high solar irradiances. At some instances, the net output power of solar PV panels with forced air cooling is greater than that with natural air cooling. The net output power of an 80Wp solar panel can increase by 2 5 W. It is estimated from the experiment results that the optimal speed of forced air cooling is within the range of 0.5 - 2 m/s.