  Solar grade silicon (SoG-Si) is a key material for the development of
crystalline silicon photovoltaics (PV), which is expected to reach the
tera-watt level in the next years and around 50TW in 2050. Upgraded
metallurgical grade silicon (UMG-Si) has already demonstrated to be a viable
alternative to standard polysilicon in terms of cost and quality. This study
presents the life cycle assessment (LCA) of UMG obtained by the FerroSolar
process. Moreover, it shows the environmental impacts of PV modules and
electricity generation based on this material. For this, an exhaustive review
of the life cycle inventory (LCI) of PV value chain, from metallurgical grade
silicon (MG-Si) down to electricity generation, has been carried out updating
inputs for all processes. The Balance of System (BoS) has also been updated
with real state of the art data for a fixed open ground large PV site (100 MW).
Two different electricity mixes, with low and high carbon intensities, have
been considered. The results reveal that for PV electricity generation using
UMG instead of polysilicon leads to an overall reduction of Climate change (CC)
emissions of over 20%, along with an improvement of the Energy Payback Time
(EPBT) of 25%, achieving significantly low values, 12 gCO2eq / kWhe and 0.52
years, respectively. Moreover, it is shown that UMG silicon feedstock is not
the main contributor to the carbon and energy footprint of the produced
electricity, leaving the first place to PV module manufacturing.
