27%-efficiency silicon heterojunction cell with 98.6% cell-to-module ratio driving new momentum towards the 29.4% limit

Silicon heterojunction technologies based on both-sided nanocrystalline contact layers currently offer the best passivation for commercial solar cells. We further improved this structure with rear-side polishing and progressive RF/VHF PECVD film deposition methods for doping layers, enabling high-pace mass production while maintaining notable passivation quality. Following this optimization, a certified cell efficiency above 27.0% and a fill factor of 87.06% are achieved on a large-area rectangular wafer (210 mm half-cell). With a multibusbar round-ribbon (smart-wire) design, we demonstrate a certified module efficiency of 25.44% and a module fill factor above 86% (for the first time) under a masked area of 1.63 m2, which is on par with the current world record module efficiency typically held by back-contact cell structures. Remarkably, the high VOC × FF value of 0.652–0.655 V was backed by a solid cell-to-module ratio of 98.6%. With respect to silicon single-junction solar cells, this work demonstrates significant progress toward Auger recombination dominance, a factor that is more critical than reducing front-side optical shading to approach the 29.4% efficiency limit. Achieving efficiency by approaching the theoretical limit in silicon heterojunction solar cells remains challenging. Here, the authors fabricate devices using rear-side polishing and progressive RF/VHF PECVD film deposition schemes for doping layers, realizing a certified cell efficiency of 27.0%.