Reduced power degradation in bifacial PERC modules by a rear silicon oxide additive layer

Summary In this paper, we investigate the influence of silicon oxide (SiO x ) layer on the potential induced degradation (PID) of P‐type monocrystalline PERC cells and modules. A SiO x layer was added between the aluminum oxide (AlO x ) and silicon nitride (SiN x ) layers on the rear side of PERC cells using a newly designed plasma enhanced chemical vapor deposition (PECVD) tool, MAiA from Meyer Burger. The performance of cells and modules with this AlO x  + SiO x  + SiN x stack was characterized by electrical breakdown (EBD), cell degradation indicator (CDi) and climate chamber PID tests. The EBD test results indicate that the AlO x  + SiO x  + SiN x stack has higher breakdown voltage than the typically used AlO x  + SiN x stack. After undergoing CDi tests, power degradation is more severe in PERC cells with AlO x  + SiN x passivation stack than those with AlO x  + SiO x  + SiN x passivation stack, as evidenced by darker photoluminescence. Bifacial modules made from PERC cells with the AlO x  + SiO x  + SiN x rear passivation stack demonstrate a significant reduction in rear PID from 12.3% to 4.2%. The results above depict that the addition of a SiO x layer between the AlO x and SiN x layers could effectively reduce the transfer of positive charges from the SiN x layer into the AlO x layer.