FoilMet®-Interconnect: Busbarless, electrically conductive adhesive-free, and solder-free aluminum interconnection for modules with shingled solar cells

The investigation of novel cell-to-cell interconnection methods has gained importance with the increase of wafer sizes. Shingling (i.e., overlapping) of solar cells is not only a solution for the interconnection of smaller solar cells but also a chance to increase the output power density by (i) increasing the active cell area within the module, (ii) decreasing shading losses, and (iii) reducing electrical interconnection losses. Replacing the commonly used expensive materials such as the silver in the cell's electrodes and the electrically conductive adhesive increases the attractiveness of a shingled interconnection. This article introduces the FoilMet®-Interconnect, an approach using laser-welded aluminum foil, for shingling and presents two solutions for configuration. With the production of aluminum foil-based shingle strings and modules, saving 36.7% of silver, a proof of concept was successful. In subsequent measurements, an efficiency of iFoilMet = (21.0 ± 0.2)% was achieved with foil-based strings of three shingled cell. Temperature cycle tests after encapsulation indicate the applicability and durability of the approach.