Last year researchers from the Massachusetts Institute of Technology (USA) showed that thermoelectrics are an attractive alternative for converting solar energy into electricity. They designed a device that relies on the transformation of light into heat, which is stored in a solar absorber material, and then transformed into electricity by means of a single thermoelectric unicouple of nanostructured Bi2Te3. Unlike solar cells, this device is not based on exciting electron-hole pairs but the sunlight is stored as heat in the solar absorber, providing a very high temperature at the top side of the thermoelements. On the contrary the bottom side is contacted at a Cu heat sink. The whole system is encapsulated in a tube which is evacuated, reducing significantly heat losses and achieving a large temperature difference that is converted into electricity.
The novel Solar Thermoelectric Generator (STEG) shows a peak efficiency of 4.6% (7–8 times higher than previous flat-panel STEG). This new approach has the potential to achieve cost-effective conversion of solar energy into electricity. The video below from the program Science for the Public provides really interesting information about this novel development directly from Prof. Gang Chen, its inventor.