Effective way to reduce rear-side potential-induced degradation of bifacial PERC solar cells

While bifacial p-type silicon (p-Si) passivated emitter and rear cells (PERCs) have dominated the current photovoltaic industry, potential-induced degradation (PID), especially in the rear-side, has become a big issue in their practical applications. Here, we have investigated the impact of different rear passivation layers on the anti-PID and electrical property of bifacial p-Si PERCs. Both simulation and characterization showed that the introduction of SiNx films with a high refractive index and additive oxide films were in favor of reducing the rear PID effect. Finally, we proposed a combined structure of stack films as the rear passivation layer, yielding an absolute front-side and rear-side efficiency improvement of 0.09% and 0.18% with 800 pieces of 166 × 166 mm2 Si wafers on the production line, and the rear PID related power loss dropped from the baseline of 5.46%–1.05% and 5.15%–0.56% by single-cell modules and commercial glass-glass modules, respectively. Together with the well-solved front-side anti-PID technique in industry, the presented novel rear passivation layer establishes a base for the efficient applications of the bifacial p-Si PERCs.