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

Abstract

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.

Passivating Contacts for Crystalline Silicon Solar Cells: An Overview of the Current Advances and Future Perspectives

“…[32] The AlO x /SiN x stack enhances the passivation effect and protects the AlO x film from potential reactions with Ag paste during the firing process. [33,34] This stack has been extensively utilized in ntype silicon cells such as n-PERL and TOPCon, serving as the front surface functional layer.…”

Review of Potential‐Induced Degradation in Bifacial Photovoltaic Modules

“…For that purpose, ARC having a higher RI can be used as more UV light can be absorbed, increasing the layers electrical conductivity. [ 53,129,174,175 ] Pingel et al have also demonstrated that ARC with higher RI shows better PID‐s resistance even in dark with an enhanced effect using thin and homogeneous layers. [ 28 ] A strategy to benefit from high RI without enhancing parasitic optical absorption [ 176 ] is to use a stack of layers.…”

“…For instance, the incorporation of a layer between the and layers on the rear side of bifacial p ‐PERC cells significantly increases PID‐p resistance. [ 175 ] This is attributed to the higher breakdown voltage of the stack. Ma et al [ 178 ] have also demonstrated better PID resistance of bifacial p ‐PERC cells by inserting a layer into the and stacks on the front and rear sides, respectively.…”