Current solar technologies are split between using the light or heat from the sun’s rays to produce electricity. Now, Stanford has developed a device that can use both, boost efficiency by 200%, and cost less than oil.
Named “photon enhanced thermionic emission,” PETE harvests more energy than photovoltaic and thermal conversion technologies. Nick Melosh, assistant professor of materials science and engineering, and his research group have shown that this revolutionary solar advancement really can work, and he says the materials used in this new device are inexpensive and readily available.
This is critical to making the product cost-effective enough to compete with oil. Photovoltaic cells are usually made of silicon, which can only use a fraction of the light spectrum it receives, resulting in efficiencies under 25%. The rest of that light energy is lost to heat, making the solar panel even less efficient. In fact, at 100 degrees Celsius, they are completely useless.
However, this new technology increases in efficiency as temperatures rise. This affinity for heat makes them ideal for solar-concentrating parabolic dishes. Efficiency is predicted to reach 50% under solar concentration, and the amount of semiconducting material needed is very small. Cesium is the key to taking advantage of both light and heat to produce electricity. A thin coat of this metal over a semiconducting material is enough to do the trick. One next step is to find the right semiconductor.
Dialing in to existing systems, the ability to add this device to solar designs already in use recognizes huge cost benefits. The excess heat hitting the PETE device would simply be dumped directly into the thermal conversion system already in place. Anything to decrease cost is an advancement of the solar industry, as this is the biggest hurdle for adoption.