University of Utah electrical engineers have designed a thin layer of polychromat material that concentrates sunlight. The researchers say the transparent glass- or plastic-based layer could be integrated into the cover glass of a solar panel to boost the overall efficiency of solar cells by up to 50%.
Conventional solar cells only absorb a narrow range of wavelengths very efficiently. The energy at other wavelengths is not absorbed at all or is converted into waste heat. In this new study, Rajesh Menon, assistant professor of electrical and computer engineering, and Peng Wang, an electrical engineering graduate student, designed a polychromat layer that enabled more wavelengths of light to be absorbed by a photovoltaic cell, increasing its conversion efficiency by 16%.
The researchers also developed computer simulations of a polychromat placed on a solar cell with eight different absorber layers to show a theoretical efficiency greater than 50%.
"These colors can be absorbed by appropriate solar cells to increase the efficiency of the overall process without increasing the cost,’ Menon says.
The polychromat was 50 mm wide by 10 mm long, with 3 µm wide grooves to sort incoming light. The layer was made using photolithography for the study, but Menon says it can be made cheaply by creating a mold of the polychromat and then stamping it out like a DVD.
Menon says the next step is working with solar cell manufacturers, which could lead to production high-efficiency solar cells in another five to 10 years. Menon and his team are also planning to test the new technology at the U.S. Department of Energy's National Renewable Energy Laboratory.
