SmartWire Solar Cell Interconnection Technology

Abstract

The SmartWire Contacting Technology (SWCT) is an innovative interconnection technology for crystalline silicon solar cells: standard busbars and ribbons are replaced by copper wires coated with a thin low melting point alloy layer and supported by a polymer foil. The SWCT provides key advantages: low temperature contacting during module lamination, increase in efficiency by lowering ohmic losses and enabling fine-line printing, reduced consumption of silver by 85 % or more, enhancement of module reliability (1000 to 2000 electrical contact points on each cell), and improved aesthetics. Automated production lines are today proposed by Meyer Burger, with a flip-flop connection avoiding previously used interconnection ribbons. The SWCT is well suited for module implementation of silicon heterojunction (SHJ) solar cells: 319.8 Wp and 327 Wp SWCT-SHJ module (20% total area efficiency) are reported, integrating SHJ solar cells produced at Choschu Industry Co. In addition, strong Ag usage reduction for monofacial (down to 10 mg Ag on the front side) as well as for bifacial SHJ cells (down to 15 mg per side) are demonstrated. High reliability is confirmed with < 5 % degradation for up to 4000 hours of damp heat and 800 thermo-cycling tests. Finally, further cost reduction potential is demonstrated with first results of replacement of state-of-the-art InSn wire coating by a BiSn alloy.