Siemens and Siemens-like Processes for Producing Photovoltaics: Energy Payback Time and Lifetime Carbon Emissions

Polysilicon photovoltaics are expected to play a critical role in addressing the projected electrical energy shortfall this century. This paper reviews the Siemens and Siemens-like processes for producing high-purity silicon necessary for photovoltaic applications, focusing on their energy payback time (EPBT) and lifetime carbon emissions. The study summarizes historical developments and recent advancements in these production methods, highlighting the significance of new processes that convert metallurgical silicon to trichlorosilane and deposit purified silicon through the decomposition of silane. By evaluating the life cycle assessments of solar cells formed from silicon sourced from these processes, the study compares their environmental impact against electricity produced from fossil fuels. The findings suggest that while traditional Siemens plants will remain influential in the short term, newer Siemens-like technologies hold the potential to surpass the older methods in efficiency and sustainability. The implications of these findings are critical for industry stakeholders as the move towards renewable energy intensifies and the search for sustainable production methods continues.