A team of scientists from the Agency for Science, Technology and Research (A*STAR) and Nanyang Technological University, Singapore (NTU Singapore) has developed technology to convert old solar cell modules into energy-harvesting thermoelectric materials, which are capable of harvesting and converting heat for electrical energy.
This technology aims to reduce the global waste generated by the silicon in the end-of-life solar cell modules.
Recycling solar cell modules is a complex and expensive process. The new technology turns this limitation into an opportunity by harnessing the contrasting properties of thermoelectrics to convert expired solar panel cells into enhanced thermoelectric materials. Among them, the addition of impurities and defects helps to enhance rather than impair performance.
In this process, solar panel cells are pulverized into a fine powder. Next, powders of phosphorus and germanium are added to alter their original properties, and the powder combination is then processed under high heat and high temperature. This process endows waste silicon with thermoelectric properties such as power conversion and cooling efficiency, improving the performance of upgraded silicon thermoelectric devices.
After several rounds of evaluation, the team achieved the optimal thermoelectric performance, and its thermoelectric figure of merit was the highest among the thermoelectric performances of elemental silicon, setting a record. The research was published in the scientific journal Advanced Materials.
"This project demonstrates the concept of phonon engineering, an efficient and useful approach to fully control the thermal conductivity of solids," said Gang Zhang, a senior scientist from the IHPC team. The IHPC team contributes to the field of material properties Expertise.
The team is also working on applying this technology to large-scale waste silicon upcycling for several high-temperature energy harvesting applications.
According to a study by the National Renewable Energy Laboratory, the average lifespan of a solar module is 30 years. It is estimated that by 2050, the number of unused components will reach nearly 80 million tons. There is no process that recycles the valuable parts of solar modules and mitigates the toxic parts, the study said.
Landfill disposal of used solar modules does not pose a significant health hazard, according to a report by the International Energy Agency. The report focuses on the potential hazards of solar module end-of-life management and the protection of raw materials used in new solar modules.
Last month, researchers at the Fraunhofer Institute claimed that they had achieved a record power conversion efficiency of 47.6 percent for a four-junction solar cell. Researchers at Surrey University and Imperial College London have developed a way to improve energy absorption in solar panel modules.
