Environmental Impact Assessment of crystalline solar photovoltaic panels’ End-of-Life phase: Open and Closed-Loop Material Flow scenarios

Abstract

The full life cycle of today's crystalline photovoltaic (PV) panel is dominated by a linear, open material flow paradigm. The Cradle-to-Cradle philosophy (C2C) applied in a Closed-Loop-Material-Cycle (CLMC) scenario seems promising to move towards a Circular Economy (CE). Environmental impacts associated with the End-of-life (EoL) phase of PV panels, particularly a CLMC scenario, have not yet been evaluated. To this end, this article uses the Life Cycle Assessment methodology to compare a linear Open-Loop-Material-System (OLMS) scenario with a novel CLMC system. Based on our results, the environmental impacts of a PV CLMC scenario are then compared with a Cadmium telluride (CdTe) panel CLMC scenario. In terms of environmental impacts, the recovery of PV materials in a CLMC scenario results in substantial improvements over an OLMS scenario. Closing the material flow has reduced the Climate Change impact factor (kg CO2 eq) by 74%, compared with the OLMS scenario. However, EoL PV recycling technology still remains behind in environmental and energy intensity terms when compared to the EoL CdTe panel recycling technology within a CLMC scenario. Furthermore, during the recycling processes, our results showed that the highest specific energy uptake was 3264 TJ for PV, while for CdTe it was 2748 TJ. On the other hand, the use of toxic chemicals to recover Si and Cd are shown to significantly contribute to the environmental impacts of both EoL PV and CdTe CLMC scenarios. Results show that the CLMC based on C2C principles has a favorable impact by reducing the environmental burden at the EoL. Nevertheless, it is imperative to reduce environmental burdens from the current thermochemical processes used to recycle silicon and to start considering the key role of C2C principles for PV panel design and recycling processes, aiming at the introduction of a CLMC system based on new standards and consistent regulations in order to reduce the environmental impacts of current PV panels, if a sustainable PV technology is desired.