Recycling solar panel waste into concrete: environmental impact of the process and the product

Silicon-based solar photovoltaic (PV) panels are the most widely deployed technology for renewable electricity generation. However, after their 25-30 year service life, large volumes of end-of-life (EoL) panels accumulate, creating significant waste management challenges. Conventional recycling methods are energy-intensive and economically unattractive, leading to landfilling as the most common disposal route. This practice raises environmental concerns due to the potential leaching of toxic metals such as lead (Pb) and zinc (Zn). In this study, we propose a sustainable recycling strategy that incorporates EoL PV panels into concrete production. Aluminium frames and junction boxes were first removed from the panels, and the remaining laminates were shredded and sieved into three size fractions. The intermediate fraction was used as sand replacement in concrete. Heavy metal leaching was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP), while the environmental impacts of landfill disposal and this recycling approach were compared using Life Cycle Assessment (LCA). TCLP results showed that Pb and Zn concentrations in this concrete were below detectable limits, whereas 3.21 mg/L of Pb and 7.34 mg/L of Zn leached from crushed laminates. LCA results indicated that landfilling imposed high environmental burdens, particularly in marine ecotoxicity (5.36E + 05 kg 1,4-DCB) and global warming potential (2.86E + 03 kg CO₂ eq.), while concrete recycling achieved reductions across all 18 impact categories, including a 69.8% decrease in non-carcinogenic human toxicity. These findings demonstrate that incorporating solar waste in concrete effectively immobilizes hazardous metals and offers a sustainable, low-impact recycling route for PV waste, significantly outperforming landfill disposal.