Status and perspectives of crystalline silicon photovoltaics in research and industry

Crystalline silicon (c-Si) photovoltaics has long been considered energy intensive and costly. Over the past decades, spectacular improvements along the manufacturing chain have made c-Si a low-cost source of electricity that can no longer be ignored. Over 125GW of c-Si modules have been installed in 2020, 95% of the overall photovoltaic (PV) market, and over 700GW has been cumulatively installed. There are some strong indications that c-Si photovoltaics could become the most important world electricity source by 2040–2050. In this Review, we survey the key changes related to materials and industrial processing of silicon PV components. At the wafer level, a strong reduction in polysilicon cost and the general implementation of diamond wire sawing has reduced the cost of monocrystalline wafers. In parallel, the concentration of impurities and electronic defects in the various types of wafers has been reduced, allowing for high efficiency in industrial devices. Improved cleanliness in production lines, increased tool automation and improved production technology and cell architectures all helped to increase the efficiency of mainstream modules. Efficiency gains at the cell level were accompanied by an increase in wafer size and by the introduction of advanced assembly techniques. These improvements have allowed a reduction of cell-to-module efficiency losses and will accelerate the yearly efficiency gain of mainstream modules. To conclude, we discuss what it will take for other PV technologies to compete with silicon on the mass market.