To make silicon photovoltaic modules involves creating metal contacts on the surfaces of the individual solar cells, then connecting those cells in series to make modules. Since the 1970’s almost all commercially produced modules have been interconnected by soldering copper ribbons to the metal contact regions on the solar cells. But today, as gains in solar cell efficiency are more difficult to achieve, attention is increasingly moving to focus on new ways of interconnecting the cells into modules in increase their performance.
Of particular interest are new module technologies that do not require high temperature soldering and can achieve high module areal efficiencies (e.g., by tiling the cells so there is no gap between them). Our research focuses on new lower temperature processes where the metal contacts of the solar cells can be bonded to the interconnection ribbons during the module encapsulation process. This can enable the interconnection of cells, such as silicon heterojunction cells, which are sensitive to the higher temperatures typically used for soldering. Our bonding methods rely on the use of low melting point solders which have the additional environmental benefit of eliminating the use of lead in modules.