Conductive adhesive based on carbon nanotubes for solar cells interconnection

The interconnection of solar cells is one of the main process steps in photovoltaic module production. Usually solar cells are connected into strings by soldering. The thermo mechanically induced stress, which is caused by high soldering temperature and different coefficients of thermal expansion, limits modules long-term reliability. The use of conductive adhesive enables the reduction of this stress significantly. Furthermore, alternative interconnection techniques for new cell and ribbon concepts are required. Conductive adhesives based on Silver (Ag) filler have been shown excellent to have performance compared to soldering. But the Ag costs have absolutely exploded in recent years. For production costs reduction and for increase in long-term reliability reasons, an alternative carbon nanotube (CNT) based conductive adhesive has been developed and investigated. This new approach has been successfully demonstrated in this study. Solar cells have been connected into modules with CNT based conductive adhesive and then compared to soldering.