Researchers at the University of New South Wales (UNSW) in Australia have produced a solar module that reached 34.5 percent conversion efficiency, which they claim set a new world record in its category of photovoltaic devices. The results were verified by the U.S. National Renewable Energy Laboratory (NREL).
“What’s remarkable is that this level of efficiency had not been expected for many years,” said UNSW’s Australian Centre for Advanced Photovoltaics Program Director and Professor Martin Green. “A recent study by Germany’s Agora Energiewende think tank set an aggressive target of 35 percent efficiency by 2050 for a module that uses unconcentrated sunlight, such as the standard ones on family homes.”
The solar cell produced record efficiencies for a four-junction photovoltaic device without using concentration, according to UNSW. It’s unique in that it actually has two solar cells, a silicon PV cell and a triple-junction cell on the other side. The researchers, led by Green and Senior Research Fellow Mark Keevers, developed a four-junction PV cell in a prism that doesn’t concentrate sunlight but splits it into specific spectrums of light.
The prism directs infrared light to the silicon PV cell and directs the other spectra of light to the triple-junction cell. “As sunlight passes through each layer, energy is extracted by each junction at its most efficient wavelength, while the unused part of the light passes through to the next layer, and so on,” according to the university.
“This encouraging result shows that there are still advances to come in photovoltaics research to make solar cells even more efficient,” Keevers said. “Extracting more energy from every beam of sunlight is critical to reducing the cost of electricity generated by solar cells as it lowers the investment needed and delivering payback faster.”
NREL maintains a regularly updated chart showing the most efficient PV devices from traditional silicon PV to thin-film PV, concentrated PV (CPV) and more. Currently the overall record holder for any PV device is one made by Germany’s Fraunhofer Institute and France’s Soitec. That four-junction champion PV cell was able to convert 46 percent of the sun’s energy into electricity, however it did so under the concentration of 508 suns.
“The new device from UNSW, according result, confirmed by the US National Renewable Energy Laboratory, is almost 44 percent better than the previous record – made by Alta Devices of the USA, which reached 24 percent efficiency, but over a larger surface area of 800-square centimeters,” the university stated. However, a glance at the most recent chart, updated on April 20 shows that a three-junction device from Japan’s Sharp achieved 37.9 percent conversion efficiency with no concentration and a five-junction cell from Boeing Spectrolab achieved 38.8 percent conversion efficiency without concentration.
The UNSW device is not likely to make it rooftops anytime soon. The triple-junction cell uses more expensive materials and is more complex than traditional flat solar panels both of which add cost. That said the research can help guide future solar research and the device is an interesting solution that demonstrates a novel and highly efficient way to convert sunlight into energy.Tweet