23% Efficiency metal wrap through silicon heterojunction solar cells

MWT-SHJ cells and modules combine the positive benefits of both underlying technologies: namely high Voc, higher Jsc and higher FF. Especially the FF is maintained before and after encapsulation thanks to the rear interconnection which strongly reduces cell to module FF losses. We obtained two record efficiencies for these devices with two different front metallizations: 22.6% using low temperature Ag paste and 23.1% using copper plating. Voc values above 730 mV have been achieved also in the new 6×6 vias metallization, demonstrating that the architecture maintains the exceptional passivation typical of heterojunction devices. The MWT cell and module structure offers even greater advantages on heterojunction solar cells: i) front side Ag consumption reduction up to a factor two; ii) concurrent low temperature cell interconnection and encapsulation. Our record MWT-SHJ solar cells and modules are manufactured using industrially proven tools and 6 inch commercial n-type Cz Si wafers. The metallization choice gives ample room to manufacturers for optimization based on internal cost structure, material costs and business strategy. MWT-SHJ behavior at reverse bias voltage and low illumination intensity is comparable to conventional HJ devices.