A new material that could one day change the efficiency of thermal solar panels has been invented by MIT and Boston College researchers, with collaborators from GMZ Energy. The thermoelectric device is at least eight times more efficient than what’s currently available in labs.
Generally, thermoelectric devices harness the temperature difference between two areas of the same material. In this case, the temperature difference is about 200 degrees Celsius, between the interior of the device and the ambient air. With no moving parts, the device that Gang Chen presented in his paper can be easily integrated into already existing hot water systems.
When you think about solar cells, if you’re a technical-minded person like me, you think about semiconductor materials. Although the thermoelectric unit developed at MIT does not involve semiconductors, it does the same thing, but with a different twist.
A black copper plate inside a vacuumed glass chamber collects heat from the sunlight hitting it, with no concentrators involved. What’s different about this black copper material is that it doesn’t re-radiate the heat it absorbs, but passes it to a state-of-the-art thermoelectric material, the active part of the system, which transforms the temperature gradient into electricity.
The efficiency is for the moment only 4.6 percent, which cannot be compared to commercially available solar cells exhibiting as much as 43 percent efficiency, with concentrators, and even more if they also gather the otherwise wasted heat. This figure is nevertheless impressive if we compare it to other simple, flat solar thermoelectric devices developed in Chen’s lab.
“With the use of other or new thermoelectric materials that can operate at a higher temperature, the efficiency may be improved further to be competitive with that for state-of-the-art amorphous silicon solar cells. This can potentially provide a different approach to realizing the $1-per-watt goal for solar-electricity conversion,” says Li Shi, associate professor of mechanical engineering at the University of Texas at Austin.