Ever since the manufacturing of PV modules began suffering from a huge price decline, the reduction of the production cost has been a task of high priority. Digitalization is a subsequent further development of the automation of today’s PV cell and module manufacturing processes and can help to decrease production costs. A central concept of digitalization is the digital twin, which represents the properties and behaviours of physical assets, materials, processes or eventually the entire production line (the so-called smart fab). Different cases of its use are presented in this paper, along with a discussion of the corresponding applications of such digital twins. Finally, a smart fab for PV production is described.