Solar designs have been inspired by leaves, windows, spray paint, and cloth. Now, a new innovation in solar technology means we can add one more inspiration to that list: the Japanese art of paper cutting, kirigami.
A study published Tuesday in Nature Communications outlines how thin, flexible solar cells shaped like cut paper would work — and how they could end up being more efficient and better at tracking the sun than conventional panels. Trackers that enable solar panels to tilt as the sun moves across the sky already exist, but according to the study, they’re often overlooked due to their heaviness and high cost — a cost that, the study notes, is actually increasing each year, even as overall solar costs continue to fall.
“As a result, residential, pitched rooftop systems, which account for ~85% of installations, lack conventional tracking options entirely,” the study reads. “To further decrease installation costs and enable new applications, a novel approach to compact and lightweight solar tracking is required.”
That novel approach was thought up by a team of researchers at the University of Michigan. Aaron Lamoureux, a PhD student at the University of Michigan and lead author of the study, said that the group brainstormed and looked at several different patterns for solar cells before arriving at the one described in the paper.
“It looks extremely simple because it is extremely simple — it’s just linear cuts,” Lamoureux told ThinkProgress. “The other patterns we looked at were harder to make, and didn’t perform as well as far as tracking goes.”
The pattern uses super-thin crystalline gallium arsenide cells — which, historically, have struggled with high costs as a barrier to success — mounted on a plastic carrier that can be pulled and bent to capture optimal sun throughout the day. That ability to track the sun is what gives this design a leg-up over traditional rooftop solar panels.
“The amount of power you get out of a given solar cell is directly related to the area that the sun sees of that solar cell. The larger the affected area is, larger the amount of power you’re going to get,” Lamoreux said. If you look head-on at a piece of paper, then start to tilt it, it’ll appear — to your eyes — thinner and thinner until you’re just looking at the edge of the paper. “That’s what happens from the sun’s perspective,” Lamoureux said.
Existing solar tracking systems use motors to tilt the solar panels as the sun moves across the sky. Lamoureux said that, since this study represents only a proof of concept — that the idea exists and could work, but that there’s still more work to be done to develop it to operational scale — they’re still looking at different options for how the cells would be moved. If they were moved with a traditional motor, it would be smaller and more lightweight than the motors for larger solar panels. The group is also looking into the possibility of using different ways to manipulate the solar cells without traditional mechanical motors, such as impulses that would cause the cells to tilt.
A quarter shows the scale of the flexible solar cells.
CREDIT: Aaron Lamoureux — University of Michigan
Lamoureux said there’s still a good deal of work to be done before the concept could be marketable. First, it would have to be scaled up — right now, the project is only about the size of a half-dollar. Researchers also need to determine how the cells fare from season to season — in high heat or extreme cold — and whether or not a different material would work better for the system. Lamoureux said the team has already started looking into some of these questions, and said that he doesn’t think any of them will prohibit the system from evolving and, potentially, making it to market.
“I definitely think that there are things that need to be addressed…but I don’t see any hard stops in that process, so I feel like all these roadblocks can be overcome with improvements in technology and a better understanding of how these things work,” he said.
He also said that, though he thinks traditional solar panels will always exist, researchers will continue to come up with innovations to make the existing technology more effective and efficient.
“Planar panels are nice because they’re easy to install on flat rooftops. The beauty of something that tracks the sun, though, is regardless of how efficient you get the [planar panels’] material, you still have these effective losses as sun moves,” he said. “As we try and further and further decrease the cost of solar electricity and increase amount of power we get, we will transition towards other types of geometries that have better performance and cost less.”