Towards 20% efficient industrial Al-BSF silicon solar cell with multiple busbars and fine gridlines

• Al-BSF silicon solar cells with multiple busbars (3-, 4- and 5-busbar) were modeled to assess the impact of multiple busbars.
• Solar cells with 4- and 5-busbar gave higher fill factor (FF) and efficiency than the state-of-the-art 3-busbar due to decreased gridline resistance.
• The modeled results were experimentally validated with 0.41%absolute and 0.66%absolute, respectively, for the 4- and 5-busbar cells compared to the 3-busbar counterparts.
• Best efficiency of ~19.94% was achieved for a 5-busbar Al-BSF cell with 239 cm2 area.

This paper reports on modeled and experimental results of industrial aluminum back surface field (Al-BSF) silicon solar cells with 3-, 4- and 5-busbar (3-, 4- and 5-BB). It was found that by keeping the same metal grid coverage, solar cells with 4- and 5-BB gave higher fill factor (FF) and energy conversion efficiency than the state-of-the-art 3-BB. This is attributed to decreased gridline resistance as the number of busbars increases from three to four, and four to five. The experimental I–V data showed an average increase in cell efficiency by 0.41%absolute and 0.66%absolute with 4-BB and 5-BB cells, respectively, compared to the 3-BB counterparts. By using the production emitter and commercial size of 239 cm2, best efficiency of ~19.94% was achieved for a 5-BB Al-BSF cell.