Solar panels are often installed on rooftops at a fixed angle. Unfortunately, this prevents them from capturing optimal energy from the sun at certain times of the day.

Although sun-tracking solar panels are already available, these are complex systems that require expensive and cumbersome mechanical parts. They also work by tilting the whole panel, which does not work on most pitched rooftop systems that make up over 80 percent of solar panel installations.

A team of researchers from the University of Michigan appears to have found a solution so solar cells could more efficiently track the angle of the sun and capture more solar energy.

Aaron Lamoureux, from the University of Michigan, and colleagues used Kirigami to develop lightweight and sun-tracking cells that can absorb significantly more solar energy. Kirigami, a variation of origami, is the Japanese art of folding and cutting paper.

For the new technique announced in a paper published in the journal Nature Communications on Tuesday, Sept. 8, the researchers cut solar cells into specific designs of kirigami to allow them to track the angle of the sun sans tilting the whole panel.

 The researchers came up with a contracting lattice structure that follows sunlight as it moves throughout the day. The concept is to stretch and twist the plastic sheet in sync with the sun's angle as it moves across the sky.

Study researcher Max Shtein, from the University of Michigan, explained that the structure morphs in a way that prevents individual strips from casting shadows on the others cells. Its "waviness" does not also detract from performance,

"Here we use kirigami (the art of paper cutting) to realize novel solar cells where tracking is integral to the structure at the substrate level," the researchers wrote in their report. "Specifically, an elegant cut pattern is made in thin-film gallium arsenide solar cells, which are then stretched to produce an array of tilted surface elements which can be controlled to within ±1°."

Lamoureux and colleagues tested the kirigami panel at a solar panel farm in Arizona and found that it generated 36 percent more photovoltaic energy than a traditional panel. The researchers likewise found that the panels are nearly as effective as the conventional sun-tracking solar arrays.

What makes these new panels better is that they are only a tenth of the weight of the trackers so they are ideal for home installations. The researchers said that these solar panels have potentials in reducing the cost of electricity generated by solar energy.

"We think it has significant potential, and we're actively pursuing realistic applications," Lamoureux said. "It could ultimately reduce the cost of solar electricity."

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