The last time we studied about photovoltaic solar panels we learned that their efficiency reduces as the panel surface heats up. However, while considering the fact that solar heat also can be used to produce renewable energy, it was just a matter a time unless someone figured out a way to develop a device that can harvest solar heat along with sunlight. A team of researchers over at Stanford have done just that and have come up with a revolutionary solar cell that they claim can be 100 times more efficient than standard photovoltaic cells.
The secret behind the innovative device is the mix of materials that can capture both light and heat to potentially boost solar cells efficiency towards the 60 percent mark, which is way beyond the 40 percent limit of conventional silicon-based solar cells. The new solar cell uses a process called photon-enhanced thermionic emission or simply PETE, in which when photon strike the semiconducting layer, electricity is produced, but the cell also has a solar cell equivalent of a turbocharger that allows it to harvest heat too.
The layered device has a layer of GaAs or AIGaAs semiconductor and the top half of the device is tuned to gather as much sunlight as possible, creating a lot of excited electrons. The underside of the device features nanoantennae, which emits these excited electrons across vacuum towards the anode. At the anode these electrons are converted into electrical current. The revolution just begins here as at the anode is a kind of a heat pipe, which collects leftover heat to be used by a steam turbine.
Unlike conventional solar PV panels, which break down at high temperatures, the Stanford device improves in efficiency as it gets hotter. While there is no dearth of possible application areas, the researchers believe that the best way to make use of the technology would be to use in concentrating solar power plants, where both sunlight and solar heat could be used to produce electricity. While the device currently has efficiency close to 2 percent, the team is confident that in the near future there should be a 10-fold gain and eventually the cells could reach an efficiency of up to 60 percent, which will help in reducing the cost of clean renewable energy.