Towards non-permanent contacting schemes for busbar-free solar cells

Abstract

The multi-busbar solar cell concept using a multitude of wires instead of few busbars is a promising candidate for large scale industrial application for several reasons: it can be combined with the probably upcoming dielectrically passivated back side (PERC) and bifacial concepts, uses less silver and allows for smaller fill factor losses when embedded in a module. However, the electrical characterization of this cell type is not straightforward as the metallization consists prior to module integration only of the finger grid and the commonly contacted busbars are missing. In this contribution several alternative approaches for non-permanent electrical contacting of busbar-free solar cells are described as the commonly used ‘external busbars’ method is found to overestimate series resistance and thus underestimates fill factor and conversion efficiency. The electrical properties of the setups are evaluated and the advantages and disadvantages are compared. In the end one concept is found to work sufficiently well.