Back contact buried contact solar cells with metallization wrap around electrodes

The authors present results on back contact buried contact solar cells based on the metallization wrap around (MWA) concept. In this cell design, the current is conducted over metallized edges of the solar cell to the rear side busbar. The applied processing sequence is almost identical to the one of conventional buried contact cells and is based on p/n-contact isolation by mechanical abrasion. One major problem of MWA solar cells seems to be the long current paths in the fingers to the collecting busbar on the rear side. Therefore device simulations were carried out in order to find the optimum grid design for different cell sizes (10×10 cm² and 12.5×12.5 cm²). The device simulations showed that the MWA solar cell concept leads to higher efficiencies as compared to conventional cells. Best efficiencies obtained in this study are η=17.5% (cell area 25 cm²) and η=16.6% (100 cm²) on Cz-Si. For mc-Si efficiencies of η=15.7% (25 cm²) and η=14.4% (100 cm²) were reached