Photovoltaic module leach testing: Database development and statistical analysis

This paper presents a database compiling 97 sample results based on U.S. Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Procedure (TCLP) testing of 33 photovoltaic (PV) modules (1–3 samples per module) of differing designs covering 16 different manufacturers. Pieces were removed from each module following the ASTM E3325 − 21 standard practice, which uses a waterjet cutting method to extract a proportional number of pieces from four representative areas within the module laminate. Laboratory TCLP results were analyzed and categorized based on several module attributes: (i) fresh vs. field-aged modules; (ii) crystalline silicon modules with traditional back-surface field (BSF) cell technology vs. modern cell technologies, such as passivated emitter rear contact (PERC), interdigitated back contact (IBC), etc.; (iii) ribbon vs. wire interconnect technologies; (iv) glass/polymer vs. glass/glass constructions; and (v) crystalline silicon vs. cadmium telluride technologies. Results reveal only 3 of the 33 modules tested would be classified as hazardous, and that a lower probability of lead (Pb) leaching from modules manufactured using one or more modern technologies (which include modern cell technologies, wire interconnect technology, and glass/glass construction) as compared to traditional technologies. Material aging appeared to be a possible cause of increased Pb leaching concentrations in two field-aged hazardous modules compared to their fresh counterparts. The study suggests less than an 8% probability of traditional technologies’ samples containing leachable Pb that exceeds the EPA Method 1311 limits when sampling using the ASTM standard practice procedure; however, the sample size was small, and expanding the database in the future is necessary to better represent the range of deployed PV technologies.