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.