Environmental Life Cycle Assessment of Passivated Emitter and Rear Contact (PERC) Photovoltaic Module Technology: IEA PVPS Task 12: PV Sustainability

The photovoltaic (PV) sector has undergone major expansions and evolutions during the last years, and the technologies that are currently marketed are numerous and very different. For Italy's energy sector, which aims to be sustainable from the environmental and economic perspective, it is important to evaluate and compare the environmental profile of the various PV generation technologies. Among high- efficiency technologies, the passivated emitter and rear cell (PERC) technology holds the largest market share. PERC modules are mostly made with half-cut monocrystalline silicon cells which allow an increase in the energy output of solar panels: by cutting the cells in half, their current is likewise cut in half, lowering resistive losses and allowing the solar cells to produce more electricity. Furthermore, using half-cut cells, the panel has more cells than regular panels, consequently the panel is divided in half so that the top and bottom halves act as two independent panels, producing electricity even if one half is shaded. In addition, the PERC cells are characterised by a rear surface passivation stack with lower surface recombination velocities and parasitic absorption than the back surface field layer in Al-BSF device. In this way, it is possible to increase the internal reflection, converting more solar energy into electricity, as compared to a monocrystalline silicon technology like aluminium back surface field technology (Al-BSF).