Repurposing of Electric Vehicle Batteries for Second Life Stationary Applications in Residential Photovoltaic Systems: An Environmental and Economic Sustainability Assessment

The increasing adoption of electric vehicles (EV) raises concerns about battery sustainability, highlighting the need for efficient repurposing strategies. This study assesses the economic and environ- mental feasibility of repurposing EV batteries for stationary energy storage units (ESU) in residential photovoltaic (PV) systems in Italy. A life cycle cost (LCC) and life cycle assessment (LCA) ap- proach is applied to compare repurposed and new battery systems, introducing Lifetime Energy Throughput (LET) as a metric for evaluating second-life performance. Results indicate that repurposing remains economically viable if new battery prices stay above €150–200/kWh. However, profitability is highly sensitive to market prices and design constraints, such as limiting depth of discharge (DOD) to 50% for prolonged secondary lifetimes, which increases ESU size by 66%. Automation and economies of scale—including robotic disassembly and standardized testing—could offset declining repurposed battery profitability, reducing disassembly time by 20–50% and labor costs by 49%. Policy incentives, such as VAT reductions or CO2 taxes, could further enhance com- petitiveness of circular business models and increase attractiveness to customers. From an environ- mental perspective, LCA results show that repurposed batteries outperform new batteries across all impact categories, reducing carbon footprint by 50–90%. A digital battery passport, mandated by upcoming EU regulations, could facilitate repurposing by improving State of Health (SOH) assessment and enabling data-sharing among stakeholders. In conclusion, while repurposing EV batteries presents significant economic and environmental benefits, sustained viability depends on policy support, automation, and standardized protocols to optimize costs and ensure market competitiveness.