Life Cycle Assessment for Balance-of-System of Photovoltaic Energy Systems

As production technologies of photovoltaic (PV) panels continue to improve, the balance-of-system (BOS) of a PV energy system account for an increasingly large share in the system’s overall environmental impacts, while little attention has been paid to BOSs from a life cycle assessment (LCA) perspective. Based on a thorough literature review, a rigorous definition and a clear system boundary of BOS were proposed in this study. A comprehensive LCA of PV BOSs was thus implemented in terms of different installation typologies. Results show that, for a 1 kW PV system, the BOS’s global warming potential (GWP) is 1.54E+05 kgCO2eq, its greenhouse gas (GHG) emissions are 1.67E+05 kgCO2eq, and its cumulative energy demand (CED) is 2.04E+06 MJ. In the BOS, car-based mobile washing contributes to the major impacts, while system mounting and module interconnection have major environmental impacts. In the installation typologies, in-roof slanted turns have relative advantages over the others in terms of environmental impacts.