Electrode Design for Wire Interconnected Back Contact Solar Cells

Back contact back junction (BC-BJ) solar cells are a well-studied cell concept for high efficiency silicon solar cells. Wire interconnection is a known approach for the interconnection of solar cells with electrodes on front and rear side but has only recently been investigated in combination with back contact concepts [1]. Here, an optimal electrode design has quite different requirements. This study determines the smallest possible electrode geometry for linear electrodes on BC-BJ solar cells by conducting peel tests on geometry variations. Moreover, it is shown that the reliability of the wire interconnection is improved by implementing an optimized H-shaped pad geometry. Consequently, the H-shape is applied on BC-BJ half-cells and evaluated based on peel force measurements, as well as electroluminescence images of wire interconnected half-cells. A significant increase of peel force from below 0.1 N for linear pads to above 0.3 N for H-shaped pads, as well as a significant decrease of failure rate from 12.5 % for linear pads down to 4.5 % are demonstrated.