Stanford engineers developed a new way of harnessing the sun’s energy with a new type of solar voltaic that creates power from both the light and heat radiation from the sun. The new technology, photon enhanced thermionic emission, is a a bit of a mouthful, but it’s better known as PETE. The Stanford engineers who are developing PETE said the new process could more than double the efficiency of existing solar cell technology. And they contend that it could significantly reduce the cost of solar energy production making it cost-competitive with oil.

PETE has a significant advantage over most photovoltaic technology because while almost all PV becomes less efficient with heat, this new technology becomes more efficient with heat.

“The proposed solar converter would operate at temperatures exceeding 200 °C, enabling its waste heat to be used to power a secondary thermal engine, boosting theoretical combined conversion efficiencies above 50 percent.” That’s according to a research paper published in Nature Materials on Aug. 1 by the team of Stanford researchers. The team was led by Nick Melosh, an assistant professor of materials science and engineering at Stanford.

PV cell efficiency suffers under heat because small quasiparticles called phonons are excited as they heat up. And as they get excited, they impede the movement of the electrons in a PV cell that produce electricity. The researchers found that the material was able to use both light and heat radiation to produce electricity.

"What we've demonstrated is a new physical process that is not based on standard photovoltaic mechanisms, but can give you a photovoltaic-like response at very high temperatures," Melosh asserted. "In fact, it works better at higher temperatures. The higher the better."

The process works best at temperatures above 200 degree Celsius (water boils at 100 degrees Celsius), where most PVs cease to produce power.

The researchers theorized that the process could be adopted to existing PV, but will work best in solar concentrators, which can reach temperatures of 800 degrees Celsius. A final advantage of the process is that the materials needed to build PETE are inexpensive and readily available, so resulting products will likely be inexpensive.