Turning Heat Into Light Could Make Solar Panels 80% Efficient, Rice Researchers Say

Don’t get too excited. What follows is a report about theoretical research in the lab which is a long way from commercial viability, but the implications of that research are simply staggering. Heat is the enemy of today’s solar panels. If they get too hot, their efficiency plummets. Researchers are working on ways to siphon some of that heat off and use it for other purposes, like making hot water. Others are exploring elaborate cooling systems that would add cost and complexity to solar systems.

Scientists at Rice University are taking a different approach — turning heat into light which can then be used to make electricity. They say their research could ultimately lead to solar panels that are 80% efficient. That would make panels that are four times more efficient than any commercially available  panels today.

“Any hot surface emits light as thermal radiation,” Gururaj Naik, an assistant professor of electrical and computer engineering at Rice, tells PV Magazine. “The problem is that thermal radiation is broadband while the conversion of light to electricity is efficient only if the emission is in a narrow band.”

The research team has come up with the idea of using a film of carbon nanotubes to create a “hyperbolic thermal emitter” which can operate at temperatures as high as 700 degrees Celsius. The device only allows electrons to travel in one direction. By squeezing the photons emitted as heat into a narrower band, light is produced that can then be absorbed by a solar cell.

“By squeezing all the wasted thermal energy into a small spectral region we can turn it into electricity very efficiently. The theoretical prediction is that we can get 80% efficiency,” Naik says. The next step for the researchers will be to combine the hyperbolic thermal emitter with a solar cell. The results of the research to date have been  published in the journal ACS Photonics under the title “Macroscopically Aligned Carbon Nanotubes as a Refractory Platform for Hyperbolic Thermal Emitters.”

Okay, let’s be honest. This research is a long way from producing a hyper efficient solar panel. But if a panel is possible that is 4 times more efficient than anything available today, that is something CleanTechnica readers should know about and now you do. You’re welcome!