Scientists used principles from the ancient Japanese paper paper-cutting technique kirigami to create lightweight solar cells with the ability to capture 40 percent more energy than conventional devices.
Solar cells are much more energy efficient when they are able to track the sun across the sky, but most of today's motorized trackers are too heavy to be placed on the roofs of buildings or vehicles, the University of Michigan reported. This new breakthrough could lead to solar cells that "have it both ways."
"The design takes what a large tracking solar panel does and condenses it into something that is essentially flat," Aaron Lamoureux, a doctoral student in materials science and engineering and first author on the paper, according to Nature Communications.
Residential rooftops account for about 85 percent of solar panel installations in the U.S., but these types of surfaces would need significant reinforcement to support a heavy conventional sun-tracking system. In order to fix this problem, a dual team of scientists and artists developed an array of small solar cells that can tilt within a larger panel to keep their surface perpendicular to the sun's rays.
"The beauty of our design is, from the standpoint of the person who's putting this panel up, nothing would really change," said Max Shtein, associate professor of materials science and engineering. "But inside, it would be doing something remarkable on a tiny scale: the solar cell would split into tiny segments that would follow the position of the sun in unison."
The researchers experimented with different patterns, and created an array that tilts and spreads apart when the sun's rays hit it from low angles, increasing the effective area and allowing more sunlight to be absorbed. The team cut this pattern into the space-grade plastic Kapton using a carbon-dioxide laser. The pattern is made up of cuts composed of simple dashes, causing the plastic to appear mesh-like when pulled apart. The material was attached to custom-made solar cells to create an ultra-efficient device. The cell offers a 36 percent improvement over a stationary panel. While conventional tracking solar devices are 46 percent more efficient than the stationary panels, they are much heavier and prone to catching the wind.
"We think it has significant potential, and we're actively pursuing realistic applications," Shtein said. "It could ultimately reduce the cost of solar electricity."
The study was funded by the National Science Foundation and NanoFlex Power Corporation.
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