Passivated busbars from screen-printed low-temperature copper paste

A screen-printable copper paste has been developed by Dow Corning to replace the standard screen-printable silver paste for use in front busbars for solar cells. Solar cells produced with these ‘passivated copper busbars’ have shown increased conversion efficiency due to an improved device operating voltage and current while maintaining a similar fill factor when compared to cells with standard ‘fired-through’ silver busbars. In addition to the improved cell efficiency, the use of copper paste may provide major cost savings compared to the use of silver, potentially giving a very significant reduction in cost per Watt. 60-cell modules have been produced at Trina Solar with passivated copper busbars, showing similar performance to the reference modules with silver busbars. Module reliability has been shown to be well in excess of the IEC 61215 standard requirements.