Industrial Silicon Solar Cells Applying the Passivated Emitter and Rear Cell (PERC) Concept-A Review

Even though the passivated emitter and rear cell (PERC) concept was introduced as a laboratory-type solar cell in 1989, it took 25 years to transfer this concept into industrial mass production. Today, PERC-type solar cells account for 10% of the worldwide produced solar cells, and their share is expected to rapidly increase up to 35% within the next few years. Record efficiencies up to 22.1% of industrial PERC cells approach an efficiency of 22.8% of the lab-type PERC cell in 1989. This paper reviews the most important research results and technological developments of the past 25 years, which enabled the successful transfer of the lab-type PERC concept into industrial mass production. Particular attention is paid to the development of AlOx/SiNy layer stacks with excellent rear surface passivation properties and low production costs. In addition, we summarize the most important research results and technological improvements of industrially processed local aluminum rear contacts. Furthermore, we describe the most relevant process flows to manufacture industrial PERC cells and address silicon wafer material requirements regarding high and stable charge carrier lifetimes. An outlook is provided on future development opportunities, which may further increase the conversion efficiency and the energy yield of industrial PERC solar cells.