Scientists at the National Renewable Energy Laboratory (NREL) have created a solar cell with an efficiency of nearly 50%.
The six-junction solar cell now holds the world record for the highest solar conversion efficiency at 47.1%, which was measured under concentrated illumination. A variation of the same cell also set the efficiency record under one-sun illumination at 39.2%.
“This device really demonstrates the potential of multijunction solar cells,” says John Geisz, a principal scientist in the high-efficiency crystalline photovoltaics group at NREL.
To construct the device, NREL researchers relied on III-V materials – called such because of their position on the periodic table – that have a wide range of light absorption properties. Each of the cell’s six junctions (the photoactive layers) is specially designed to capture light from a specific part of the solar spectrum.
The device contains about 140 total layers of various III-V materials to support the performance of these junctions, and yet is three times narrower than a human hair. Due to their highly efficient nature and the cost associated with making them, III-V solar cells are most often used to power satellites.
France described the potential for the solar cell to exceed 50% efficiency as “achievable” but that 100% efficiency cannot be reached due to the fundamental limits imposed by thermodynamics.
NREL is the U.S. Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by The Alliance for Sustainable Energy LLC. NREL is also engaged in reducing the cost of III-V solar cells, enabling new markets for these efficient devices. The U.S. Department of Energy Solar Energy Technologies Office funded the research.
Photo: Scientists John Geisz (left) and Ryan France (right) created a solar cell that is nearly 50% efficient