Wire bonding as a cell interconnection technique for polycrystalline silicon thin-film solar cells on glass

Abstract

The interconnection of solar cells is a critical part of photovoltaic module fabrication. In this paper, a high-yield, low-cost method for interconnecting polycrystalline silicon thin-film solar cells on glass is presented. The method consists of forming adjacent, electrically isolated groves across the cells using laser scribing, and then forming wire bonds over each laser scribe, resulting in series interconnection of the individual solar cells. Wire bonds are also used to connect the first and last solar cell in the string to external (tabbing) leads, forming a mini-module. A layer of white paint is then applied, which acts as both an encapsulation layer and an additional back surface reflector. Using this method, an 8.3% efficient minimodule has been fabricated. By exploiting recent developments in wire bonding technology, it appears that this process can be automated and will be capable of forming solar cell interconnections on large-area modules within relatively short processing times (∼10 min for a 1 m2 module). Copyright © 2010 John Wiley & Sons, Ltd.