The proliferation of solar panels on roofs and in solar farms over the last 20 years is expected to create a new problem – what to do with the panels at the end of their lives? An estimated 8 million tons of waste per year is expected by 2030 and ten times that by 2050. Typically, a panel will produce power for about 30 years, though the power declines several percent each year. But at the end of life, panels cannot be simply recycled into new panels.
Current recycling usually involves collecting and recycling the metal frames and glass. The silicon, which makes up 90% of the panel, ends up in a landfill because silicon used in new panels must be pure. However, scientists at the Agency for Science, Technology & Research (A*STAR) and Nanyang Technological University, Singapore (NTU Singapore) have a solution, highlighted in an Interesting Engineering article.
Thermoelectric materials produce electricity when exposed to a temperature difference. When one side is exposed to heat, while the other side is exposed to a cooler environment, the material produces a small electric charge. The silicon in an old panel can be ground into a powder, some doping elements added, and converted into an efficient thermoelectric cell. The presence of impurities actually helps improve the efficiency. The potential is to create massive banks of panels made of cells that can convert heat from thermal processes and even sunlight into usable electricity. – Steve Terry, DTC HVAC & Refrigeration Instructor
