Naturally Occurring Radioactive Materials and Heavy Metals in Photovoltaics: Insights into Short- and Long-Term Waste Hazards

Global advancement of solar energy and its emerging technologies are good indicators to assess the general response of energy users to clean energy as enshrined in the sustainable development goal (SDG) 7. However, the reality that solar panels and other components would become electronic waste someday and ultimately contribute to chemical hazards in the environment is a source of concern. This study aimed to evaluate the amounts of heavy metals in solar photovoltaic (PV) modules using atomic absorption spectroscopy and estimate the health risks associated with these heavy metals. Six samples of solar PV were collected and evaluated for Chromium (Cr), Cadmium (Cd), Lead (Pb), and Arsenic (As). Using the health risk index (HRI) and the target hazard quotient (THQ), the human dangers presented by the presence of heavy metals were evaluated. The heavy metal content ranged as follows: Pb (6.00–6.25 mg/kg); Cd (0.10–1.25 mg/kg); Cr (8.00–12.00 mg/kg); and As (0.60–1.25 mg/kg). An estimate of the average weight for children and adults was used to calculate the health risk index. The result showed that health risks for children and adults are high with heavy metal concentrations escalating in the order Pb > Cd > Cr > Ar. The THQ in all metals was < 1 in all the solar PV samples, which indicates they do not pose serious health risk concerns in a single panel. However, considering the large number of waste panels, the risk would be significant. Also, it was found that there were naturally occurring radioactive materials (NORM) in the PV modules and their effects are more in the short term. Hence, heavy metals are envisaged as long-term hazards, and NORM in PV modules are envisaged as short-term hazards. Using the EPA dose compliance concentrations (DCC) (EPA-DCC), the radioactive exposures from the selected photovoltaics were proven to be directly dependent on the number of PVs in use and their distance from the PV installations. Several recommendations were made to curb death in the process of pursuing cleaner energy technologies.