Reliable Interconnection of the Front Side Grid Fingers Using Silver-reduced Conductive Adhesives

Electrically conductive adhesives as an alternative interconnection technology can potentially avoid the need for busbars on crystalline silicon solar cells. The adhesive is applied to the grid fingers and the ribbons for module integration can be directly attached to them. We analyze the interconnection related power losses by establishing an electrical model and validating the model with experimental I-V curve data. The maximum error is 7% for one-cell-minimodules. In the following, we select silver-reduced adhesives and tin-coated ribbons to build minimodules and perform environmental chamber tests. The interconnection related cell-to-module losses are higher by 0.5% compared to standard soldering on busbars. The minimodules with silver-reduced glues and tin-coated ribbbons are stable in 1000 h damp heat and degrade by a maximum of 3% after 200 thermal cycles. Only the highly Ag-filled acrylate failed the thermal cycling test.