PILOT LINE PRODUCTION OF INDUSTRIAL HIGH-EFFICIENT BIFACIAL N-TYPE SILICON SOLAR CELLS WITH SELECTIVE BACK SURFACE FIELD PROCESS

摘要

The back side of Bifacial N-type Si solar cells has to be highly doped to form back surface field (BSF), this results in low contact and good fill factor. However, highly doped back surface field increased Auger recombination and high surface recombination. The motivation to form selective back surface field on n-type cells from the selective emitter known for p-type cells. This paper applied two different process to create selective back surface field and developed industrially applicable production sequence. The first one uses commercial etching paste by screen printing to etch the regions between the contact metallization . The second process utilizes the wet chemical etch back process where the areas intended for metallization are protected from etching by an acid resistant barrier. Both techniques attain significant improvement (0.3% _(abs) efficiency gain for etching paste and ＞0.4% _(abs) for etch back process) compared to standard cells with homogeneous back surface field. The influence of cell parameters and its distribution are discussed, respectively.