Researchers from UNSW and DAS Solar have developed a zero-busbar metal grid optimization approach for tunnel oxide passivated back-contact (TBC) silicon solar cells, reducing silver consumption by 3-4 mg/W. The first TBC cells produced using this technique have achieved efficiencies exceeding 27%. The ZBB design cuts silver paste consumption significantly, supporting large-scale industrialization of TBC solar cells. DAS Solar has begun mass production of ZBB TBC cells with silver consumption of approximately 6 mg/W and peak conversion efficiency exceeding 27%. The cell design includes textured front surface with passivation layers and relies on p-type and n-type polycrystalline silicon at the rear side. The article also discusses the benefits of larger busbar segmentation and efficient current routing in improving solar cell efficiency, comparing ZBB cells with pad-based cells. The study found that ZBB cells offer at least a 0.1% efficiency gain over pad-based cells, with potential for further improvement with reduced silver paste consumption. DAS Solar introduced a circuit-model-based method to detect hot-spot risks in TOPCon back-contact modules, addressing limitations of existing approaches.