Crystalline Silicon Solar Cells - State-of-the-Art and Future Developments

Crystalline silicon solar cells have dominated the photovoltaic market since the very beginning in the 1950s. Silicon is non-toxic and abundantly available in the earth crust, silicon PV modules have shown their long-term stability over decades in practice. The price reduction of silicon modules in the last 40years can be described very well by a learning factor of more than 20%, i.e. doubling the cumulated module capacity results in a reduction of module prices by 20% - due to both, efficiency increase and cost reduction per PV absorber area. The latter can be attributed to savings in material cost and strongly increased productivity. Interestingly the price experience curve indicates that the learning has been even around 40% since 2006 (ITRPV, 2021). Production has exploded in the last years, reaching a new record value of more than 150GWp in 2020 (Philipps and Warmuth, 2021b). To extend the success story of this photovoltaic working horse, it is important to further bring down the costs. The cost distribution of a crystalline silicon PV module is clearly dominated by material costs, especially by the costs of the silicon wafer. Therefore, besides improved production technology, the efficiency of the cells and modules is the main leverage to bring down the costs even more. This chapter describes the state-of-the-art process for silicon solar cells and gives insight into advanced processes and cell designs.