Creating Power from Both Light and Heat

A key component of new solar panel technology being tested at Stanford. (Photo: Nick Melosh)

In a kind of cruel paradox, heat has always been the enemy of solar panels.  At higher temperatures, photovoltaic cells become less efficient, which is problematic in an industry where efficiency is the name of the game. That heat also represents wasted energy.

Today, researchers at Stanford University announced that they may have helped solve that problem. Nick Melosh of Stanford’s Materials Science & Engineering department set out to make use of the wasted heat. He and his colleagues created a solar cell technology that uses both light and heat to generate electricity. It’s called “photon-enhanced thermionic emission” (or PETE for short). “This is the first time that a process has been reported that can use the heat and the photons together harmoniously,” says Melosh.

Traditionally, solar power falls into two camps; those that make solar power from sunlight, which is what photovoltaic (PV) panels do, and those that make solar power from heat, which is what concentrating solar power plants collect. Melosh is hoping that this technology would bridge the gap between the two.

The PETE process is designed to work at temperatures above 400 degrees F, much hotter than silicon solar panels can stand. For that reason, Melosh sees the panels being used in solar farms in the desert. “It’s probably not something that you would  put on your rooftop, but out in the desert, they would be perfect,” he said. Melosh hopes to see the efficiency eclipse 50%, which would be double that of most solar panels today.  The panels could also be added to existing solar thermal farms, since the high-temperature waste heat from the PETE process could be fed into system.

The technology is still confined to the lab, but Melosh hopes to see a prototype in three years. In the meantime, his lab will be testing different semiconductor materials that could boost the efficiency of the process.