Metal dissolution from end-of-life solar photovoltaics in real landfill leachate versus synthetic solutions: One-year study

To investigate the after end-of-life concerns of solar panels, four commercially available photovoltaics (reduced to 15×15 cm2 size) in broken and unbroken conditions were exposed to three synthetic solutions of pH 4, 7, 10 and one real municipal solid waste landfill leachate for one year. Metals leaching, encapsulant degradation and release, probability of leached metals exceeding their surface water limits, and change in pollution index of leachate after dumping of solar panels were investigated. Rainwater simulating solution was found to be predominant for metal release from silicon-based photovoltaics, with silver, lead and chromium being released up to 683.26 mg/L (26.9%), 23.37 mg/L (17.6%), and 14.96 mg/L (13.05%), respectively. Copper indium gallium (de) selenide (CIGS) photovoltaic was found to be least vulnerable in various conditions with negligible release of indium, molybdenum, selenium and gallium with values ranging between 0.2 and 1mg/L (0.30%-0.74%). In contrast, minimal metals were released in real landfill leachate compared to other leaching solutions for all photovoltaics. Positive correlation was observed between encapsulant release and metal dissolution with a maximum encapsulant release in silicon-based photovoltaics in rainwater conditions. The calcualtion of values of probability of exceedance of leached metals to their respective surface water limits for aluminium (multi- and mono- crystalline-silicon), silver (amorphous photovoltaic) and indium (CIGS) indicated maximum value to be 92.31%. The regression analysis indicated that conditions of the modules and pH of the leaching solution play significant roles in the metal leaching. The increase in leachate contamination potential after one-year of photovoltaics dumping was found to be 12.02%, 10.90%, 15.26%, 54.19% for amorphous, CIGS, mono and multi crystalline-silicon photovoltaics, respectively. Overall, the maximum metal release observed in the present study is 30% of the initial amount under the most stressful conditions, which suggests that short-term leaching studies with millimeter sized sample pieces do not represent the realistic dumping scenarios.