Record low ag paste consumption of 67.7 mg with dual print

Abstract

We investigate and compare three different fine line printing techniques for the silver front side metallization of industrial-type silicon solar cells: single print, dual print and print-on-print. We obtain finger heights of 5.6 μm for single print, 9.5 μm for dual print and 15.1 μm for print-on-print as well as finger width between 46.2 μm and 61.3 μm. We process PERC solar cells with dual print and print-on-print. For the dual print, we test two different bus bar designs, a standard rectangular shaped bus bar and a segmented bus bar. The resulting PERC solar cells achieve conversion efficiencies of 19.8% for dual print and print-on-print. The dual print with segmented bus bar design reduces the Ag paste consumption to 67.7 mg, measured after printing prior to drying. To our knowledge, this is the lowest front side Ag paste consumption that has been reported so far. Additionally, we model optimum Ag finger width in dependence of electrical and geometrical parameters. We find that even when assuming very optimistic parameters, the optimum finger width of 26 μm is just a factor of two lower compared to the state of the art technology today.