Smart Material for Efficient Solar Absorption without Overheating

Solar thermal collectors are used to produce hot water and contribute to home heating. During colder seasons all the energy they absorb is helpful, but in summer thermal collectors become overheated and deliver excess heat. Until recently, this overproduction has remained an unresolved problem that can even damage facilities. A team of EPFL researchers has developed a smart material that changes its properties depending on temperature. In the case of overheating during summer, this new material would allow the collector to get rid of excess energy by radiating it. The innovation of this project is the successful combination of an optical selective effect with a thermochromic function - the color reacts and changes with heat, a phase change that occurs at 68° C. The new material developed at the laboratory enables the efficient absorption of solar energy while reducing the impact of overheating.