Researchers shoot for better, cheaper solar panels

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Physics may hold the key to a more efficient solar panel, according to researchers with the Oregon Built Environment and Sustainable Technologies Center.

Many researchers are exploring whether complex nanomaterials and semiconductors can increase efficiency of solar photovoltaic panels. But researchers from the University of Oregon and Oregon State University will rely on basic physics and a basic material, silicon, to create the next generation of efficient and inexpensive solar photovoltaic panels.

Even the most efficient solar photovoltaics on the market convert only 22 percent of the sunlight absorbed into electricity, according to Steven Kevan, a physics professor and lead project investigator with the University of Oregon. And a standard solar photovoltaic system installed on a house may convert only about 13 to 14 percent of the sun’s rays.

The problem, Kevan said, is that invisible light, such as blue and ultraviolet light, passes through a solar panel without getting absorbed and instead becomes waste heat. However, Kevan believes there may be a way to capture that higher frequency light and turn it into electricity.

“We’re going to use materials we know work, like crystalline silicon, and try to devise a new process to capture that higher frequency light,” Kevan said. “With any photovoltaic, anything you do to try and improve efficiency usually makes it worse. But if we could find a practical and inexpensive way to improve the function by even 5 percent, that would be a big deal.”

The ability to create more electrons, or negatively charged particles, within a photovoltaic panel may hold the key to better efficiency, Kevan said. A physical process called impact ionization can cause an electron to decay and produce more electrons. More electrons, Kevan said, means more light that can be converted to electricity.

This research could significantly benefit solar installers like Brent Gunderson, owner of Gen-Con Inc. in Portland. An average residential photovoltaic system may cost several thousand dollars but produce only a fraction of a home’s energy. If a photovoltaic system could convert more of the sun’s rays, homeowners could get faster returns on investments, and installers could sell their products more easily.

“Anything that reduces material costs and gives us more efficiency will help,” Gunderson said. “A more efficient system means I can get the same wattage on a smaller roof area, which will help make jobs on older homes with small roofs in Northeast Portland more feasible.”

The solar industry in Oregon is hungry for an inexpensive solution to the efficiency problem, said John Audley, deputy director of the Renewable Northwest Project. As the cost for solar panels continues to decline, the ability to pitch a less expensive and more efficient panel is like gold.

“I am certain that solar industry people wake up every day trying to figure out a way to make these less expensive and more efficient,” Audley said. “They’re waiting for the innovation that will bring their prices down.”

Led by Oregon BEST, the project team – which also includes Oregon State University physics professors Janet Tate and Guenter Schneider, OSU mathematics professor Malgorzata Peszynska, UO chemistry professor Geri Richmond, and University of Illinois material science and engineering professor Angus Rockett – this fall will begin growing crystalline silicon solar film in the lab. By next summer, the solar film will be ready for testing. By using silicon, the most widely used material for solar photovoltaics, the team may be able to improve most solar devices on the market today, Kevan said.

“The chances of us producing something useful are very small,” Kevan said. “But if it works, it will be picked up in most photovoltaic systems. We’re trying to amplify the usefulness of an existing material.”

The three-year research project is funded by a $1.6 million grant from the National Science Foundation. Oregon BEST helped pay for lab equipment for the project.