Suppression Of Potential-Induced Degradation In Monofacial Perc Solar Cells With Gradient-Designed Capping Layer

The potential-induced degradation (PID) of p-type crystalline silicon passivated emitter and rear cell (PERC) is a critical issue causing severe output power loss. In this paper, a gradient-designed capping layer consisting of silicon nitride/silicon oxynitride/silicon oxide (SiNx/SiNxOy/SiOx) is proposed as the surface coating for p-type PERC solar cells. The capping layer improves the short wavelength spectral response due to its better antireflection effect. An impressive efficiency of 23.52% has been achieved on mass production line. A long-term PID evolution up to 672 h is performed for glass/back sheet PERC cell modules under stringent conditions with the ambient temperature of 85 degrees C, relative humidity of 85%, and the applied voltage of 1500 V. The current-voltage (light I-V, dark I-V) parameters of the modules were measured, as well as the electroluminescence, to evaluate the effect of sodium ion migration in PERC solar cells. It is shown that monofacial PERC solar modules suffer from shunt of PN junction under PID stress, which can be obviously suppressed by gradientdesigned capping layers. The optimized PERC solar modules show excellent PID resistance, showing great potential for lower levelized cost of energy (LCOE) of photovoltaic power generation.