Regional Institute and Industry Update: How close can we get to 29% silicon cell efficiency? | 区域研究和产业更新: 我们离29%的硅电池效率还有多远?
With the large-scale introduction of PERC cell technology and with rapid progress with both HJT and TOPCon (or n-type PERT with passivated rear contact), the efficiency of mainstream commercial cells is rapidly improving. How close can we get to 29% limit on silicon cell efficiency? This is assessed by comparison with where we are now compared to the 29% ideal and evaluating opportunities for closing the gap.
Comparison of HJT with what is needed shows it already gives close to the maximum Voc but has a Jsc disadvantage of 5% compared to the other technologies, even with TCO requirements reduced by the move to rear junctions. The near-term opportunity surprisingly lies in fill factor (FF) improvement where a 2-3% gain on present highs of 85.5% seem feasible. Eliminating the top TCO will give a Jsc boost as well as solving the indium issue, with a selective emitter approach or the switch to IBC required to remove top layer a-Si/uc-Si absorption, if HJT is to remain competitive in the long term.
With PERC and TOPCon, the opportunity lies in Voc improvement with the two technologies becoming more entwined, as a combined PERC with passivated contacts. Can Ga doping remove the n-type advantage, noting p-type TOPCon efficiencies now match or exceed those from n-type? Do rear junctions have fundamental advantages by having wafers provide the lateral transport, rather than non-ideal, heavily doped layers?