Progress in Interconnection of Busbar-less Solar Cells by Means of Conductive Gluing

In this work we focus on the optimization of busbar-less front side metallization grids to improve performance of cells interconnected by conductive glues and films. Furthermore the effect of different silver metallization pastes were studied in terms of peel strength and the influence of different ribbon coatings to the electrical performance after ribbon attachment with conductive gluing (CG). The results show that conductive glues allow the interconnection of solar cells without front busbars with Pmpp losses after encapsulation being close to soldered interconnections but with an additional saving up to 40% of front cells silver paste. It was found that different front side silver metallization pastes affect the peeling strength after curing. Specifically ribbon coating consisting of base metals tend to show electro-chemical corrosion if DH testing exceeds 1000 hours. In summary we show that CG are able to contact busbar-less solar cells and prove results in extended IEC61215 testing up to TC600 and DH2000. The paper shows that ribbon coating and metallization pastes are the key requirements to study before utilizing CG in mass production.