Physical properties of industrial 19% rear side passivated Al-LBSFR- solar cells

With the objective of high efficiency solar cells rear side passivation with local aluminium back surface field and dielectric reflection (Al-LBSFR) were developed at Centrotherm and cell efficiencies of 19.4% were achieved. In this paper major physical properties of the developed technology, named centaurus technology, are presented.A low reflection on the solar cell front side is achieved by a textured surface, which enables in particular an inclined light entry at the solar cell front side, which is mandatory for a total light reflection on the solar cell dielectric rear side. Likewise a smooth instead of a textured rear side surface was more suitable for a high rear reflection and also more appropriate for better rear surface passivation. In addition, the influence of the rear side local BSF and metallization fraction was identified as a possible Voc limitation in combination with the front emitter saturation currents. Lower temperature coefficients of the cell power output or cell efficiency and of the open circuit voltage were evaluated for Al-LBSFR cells.