21.2%-efficient fineline-printed PERC solar cell with 5 busbar front grid

We evaluate industrial-type PERC solar cells applying a 5 busbar front grid and fineline-printed Ag fingers. We obtain finger widths down to 46 m when using a stencil with 40 m opening for the finger print, whereas the busbar is printed in a separate printing step with a different Ag paste (dual print). This compares to finger widths of 62 m to 66 m when applying print-on-print. The 5 busbar front grid with the best dual print process reduces the shadowing loss of the front grid to 4.0% compared to 5.8% for a conventional 3 busbar front grid printed with print-on-print. The 1.8% reduction in shadowing loss results in equal parts from the reduced finger width with dual print as well as from a reduced total busbar width of the 5 busbar design. The resulting PERC solar cells with 5 busbars demonstrate independently confirmed conversion efficiencies of 21.2% compared to 20.6% efficiency of the 3 busbar PERC solar cell. The increased conversion efficiency is primarily due to an increased short-circuit current resulting from the reduced shadowing loss. To our knowledge, 21.2% conversion efficiency is the highest value reported so far for industry typical silicon solar cells with printed metal front and rear contacts. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim