Silicon Based Photovoltaic Cells For Concentration–Research And Development Progress In Laser Grooved Buried Contact Cell Technology

The Laser grooved buried contact silicon solar cell (LGBC) process employed by Narec currently produces LGBC cells designed to operate at concentrations ranging from 1 - 100 suns and has demonstrated efficiencies at 50X of over 19% and at 100X of over 18.2% using 300 mu m CZ silicon[1] wafers. As part of the LAB2LINE[1], APOLLON[2] and ASPIS[3] projects funded under the European Commission Framework Programs (FP6 and FP7) we have made improvements to the LGBC process to improve efficiency or make the cell technology more suitable for industrial CPV receiver manufacturing processes. We describe a process which hybridizes LGBC and more standard screen printing technologies which yields at least a 6% relative improvement at concentration when using more readily available 200 mu m thick CZ wafers. We describe a pioneering front dicing technique (FDT). The FDT process is important in small cells where edge recombination effects are detrimental to the performance. We show that by using this new technique we can produce cells that perform better at concentration and improve the positioning of the front contact of the cell. We also describe a busbar technology that uses laser processing and electroless chemical plating to allow not only soldering to the front contact of the cell but also wire bonding. The advances in research and development of LGBC cells leading to improved cell performance may provide significant reductions in levilised cost of energy (LCOE) for low to medium CPV systems.