Guiding the environmental design of a novel solar absorber through life cycle assessment by identifying anticipated hot spots

Life cycle assessment (LCA) can be a powerful tool in minimizing aggregate life cycle impacts if used during early stage research before materials, processes, and system designs are set. This study examines the life cycle effects of substituting two promising arsenic-containing polymorphs of Cu3AsS4 as the absorber layers in single junction thin-film photovoltaic (PV) cells. These thin films and the auxiliary components they require to create functioning PV systems are compared with existing commercial PV systems, including crystalline silicon, cadmium telluride (CdTe), and copper indium gallium diselenide (Cu(In,Ga)Se-2). The resulting impacts for Cu3AsS4 are expressed as a range of equally possible values to reflect the design choice uncertainties in this early-stage LCA. Hot spots are identified to determine the most relevant contributors to PV system impacts and uncertainty ranges. Scenario analyses are performed to quantify the change in life cycle impacts due to mounting configuration and product performance. Calculated impacts and identified hot spots suggest Cu3AsS4 PV systems are consistent with commercial PV technologies. Notable design considerations include minimizing waste associated with deposition techniques that have modifiable utilization efficiencies (especially for molybdenum), designing reusable BOS components, investigating roll-to-roll compatible substrates, and prioritizing module efficiency improvements. Within the system boundaries examined here, the contribution of arsenic to the overall life cycle impacts is calculated to be less than 1% in all impact categories through both economic and mass allocations, but direct exposure through specific manufacturing and decommissioning steps were not modeled. By determining potential Cu3AsS4 life cycle impacts, identifying life cycle hot spots, and offering design options, this work serves to establish a basis on which the environmental implications of this potential thin film technology are understood. (C) 2020 Elsevier Ltd. All rights reserved.