Integrated interconnection of crystalline silicon thin film solar cells

A concept for integrated interconnected crystalline silicon thin film solar cells is presented. Following the classical thin film approach the crystalline silicon thin film is divided into individual cell stripes and interconnected monolithically, directly on the substrate. Taking advantage of the crystalline quality of the material, the interconnection is realized using screen printing pastes. In this paper we focus our experimental investigations on the separation of cell stripes and the interconnection via screen printing. The cell separation is either done by oxide masking and KOH etching or by laser ablation and a subsequent etch step. For the interconnection not only metallization pastes are required, but also an isolating material to protect the edge of the cell against shunting. Different isolating screen printing pastes were tested for their isolation properties against metallization pastes. In further experiments the influence of different firing parameters was investigated. The cell stripe width strongly affects the series resistance of the module, since it is a single side contacted concept where only the back surface field (BSF) is responsible for the electrical conductivity on the rear. Therefore the series resistance is estimated in dependence on the cell stripe width.