Leaching potential of chemical species from real perovskite and silicon solar cells

Abstract

Despite their many advantages, solar photovoltaic (PV) cells used for electricity generation can have negative environmental impacts. The chemicals necessary for their fabrication can be released into the environment during their disposal or following damage, such as that from natural disasters. The principle objective of this study was to assess the leaching potential of chemical species, primarily heavy metals, from perovskite solar cells (PSC), monocrystalline (MoSC) silicon solar cells, and polycrystalline (PoSC) silicon solar cells under worst-case natural scenarios. In all cases, real solar cells were used as opposed to the pure component. The toxicity characteristic leaching procedure (TCLP) was used to analyze the leachates from PSCs to determine the concentrations of major component species. The results showed that broken PSCs released Si, Pb, Al, As, and Ni under TCLP conditions; lead, a major component of PSCs, was released at around 1.0 mg/L at a pH of 4.93, from both broken and unbroken PSCs. However, the concentrations of these elements in the leachate were within the toxicity characteristic (TC) limits. Encapsulation of the PSCs inhibited the release of hazardous substances, but did not completely eliminate the release of metals. TCLP results from broken MoSCs revealed that metals leached at relatively high levels: Al: 182 mg/L, Ni: 7.7 mg/L, and Cu: 3.6 mg/L. The results from broken PoSCs indicated the release of 43.9 mg/L of Cu and 6.6 mg/L of Pb, which are higher than the TC limits. These high levels may be attributed to the welding materials used on the rear side of crystalline-Si (c-Si) solar cells. This study identifies the importance of encapsulating PSCs and the welding materials on the rear side of c-Si solar cells to minimize the release of toxic substances into the environment.