Energy performance and fire risk of solar PV panels under partial shading: an experimental study

Partial shading (e.g., bird droppings, leaves, dusts, and shadows) on solar photovoltaic (PV) panels not only depresses the energy performance of solar PV panels but also increases their surface temperature. Nowadays, the impact of shaded locations is overlooked, and the quantitative relationship between surface temperature and energy performance of solar PV panels under partial shading is still unknown. This has hampered the solar PV panels' energy output prediction, which is especially important for ensuring their widespread applications. Hence, this study experimentally addressed the impacts of partial shading with variations in shaded ratios and shaded locations on solar PV panels' surface temperature and energy performance. Experimental results showed that the worst scenario was at the upper right cell under 67 % shaded ratio, causing the shaded cell's surface temperature to reach 99.6 °C under 1100 W/m2 solar irradiance and 20 °C ambient temperature. However, the power of solar PV panel could decrease up to 92.9 % when the middle cell was completely shaded. From both aspects of surface temperature and power dissipation of solar PV panels, the potential reduction of energy performance was worse when the middle or bottom cells were shaded. The quantitative relationship describing power dissipation affecting temperature at shaded cell caused by partial shading was also proposed. The obtained results contribute to predicting energy outputs considering typical partial shading scenarios and offer valuable data supporting decision-making and policy formulation aimed at minimizing energy losses in solar PV systems.