Risk Assessment of Leached Heavy Metals from End-of-Life Thin Film Solar Photovoltaics

This study investigated the risk of heavy metal leaching from end-of-life thin film solar photovoltaic (PV) panels, commonly disposed of in landfills, potentially contaminating groundwater. Various heavy metals including Al, Ag, Cd, Cu, Cr, Fe, Ga, In, Mo, Ni, Pb, Se, Te, As, Mn, and Zn were studied for leaching using standard methods such as TCLP and SPLP. The research compared the efficacy of these methods and examined the announcement of the Ministry of Industry regarding the disposal of waste or unused materials, B.E. 2023. Aging processes were applied to thin film PV samples including a-Si, CIGS, and CdTe. The results from testing with the TCLP method found that Cd in the CdTe panel had a value of 1.12 mg/l, significantly higher than that of the other two panel types, and also exceeded the TCLP standard of 1 mg/l. The SPLP test found that the concentration of heavy metals tended to be similar to the TCLP method, but most were in lower amounts. The results of metal concentrations from the SPLP method were compared with the international drinking water standards of the US EPA. It was found that Cd in the CdTe panel exceeded the standard limit. Ni in the a-Si panel exceeded the standard limit and Se in the CIGS panel exceeded the standard. According to the announcement of the Ministry of Industry, the total concentration of hazardous substances (TTLC) testing found the a-Si panel had a Ni exceeding the limit. The CIGS panel had Cr, Cu, and Se exceeding the limits while the CdTe panel had a Cd exceeding the limit. This means all 3 types of panels are classified as hazardous waste. Non-carcinogenic risk assessments indicate potential risks for both adults and children primarily through skin contact, while carcinogenic risks are associated with ingestion of contaminated groundwater or skin exposure. The health risk assessment reinforces that thin-film solar panels that have reached the end of life (hazardous waste) if not disposed of properly and contaminated into the environment will affect human health. Therefore, methods must be found to appropriately manage this enormous amount of waste that will occur in the future.