Art-Inspired Solar Cells Track The Sun

Unsurprisingly, solar panels that can track the sun as it arcs across the sky show much higher efficiencies than those fixed at a given angle; on the order of 40%. However, for standard home installations, the energy expended to rotate the heavy panels counteracts the potential gains. Scientists this week report that cells based on the Japanese art of kirigami are able to circumvent this problem. Read on to find out how an old art-form is being used for thoroughly modern technology.

Solar power array: big solar plants like this have panels that track the sun, but until now that technology has been unavailable to home users.Solar power array: big solar plants like this have panels that track the sun, but until now that technology has been unavailable to home users.

Kirigami is the Japanese art of paper cutting and yields tremendously beautiful and intricate artworks in the right hands. Along with origami, the art of paper folding, its design principles have also been applied to various modern applications like airbags, optical components, space-based solar arrays, load-bearing metal structures and stretchable and flexible electronics. Now scientists have turned to this art-form once again in an effort to develop highly efficient cost-effective solar cells.

Intuitively, it is obvious that a solar panel whose surface tracks the arc of the sun will absorb more sunlight and thus generate more power. Unfortunately, the mechanics typically required to make this possible mitigate any potential gains from increased sunlight. Not only that, the cost of such machinery is prohibitive for standard rooftop home panels, which these days make up around 85% of all installations. To tackle this problem, a research team led by Max Shtein, professor of materials science and engineering at the University of Michigan in Ann Arbor, decided to break one single panel into an array of smaller panels, each of which can tilt independently. To make this tilting happen in an energy efficient manner, the team recruited Matthew Shlian, a paper artist from the School of Art and Design. Shlian demonstrated a number of kirigami techniques of which the simplest turned out to be the most practical. A single strip of material doctored with a series of horizontal cuts is able to stretch in the direction perpendicular to the cuts as in the image below.

Kirigami: a series of simple horizontal cuts completely changes the properties of this material. Image reproduced from Nature Comm., 6, 2015, 8092.Kirigami: a series of simple horizontal cuts completely changes the properties of this material. Image reproduced from Nature Comm., 6, 2015, 8092.

The team now had all the pieces necessary to develop the highly efficient array. An array of small solar panels was affixed to a piece of Kapton, a stretchable polymer renowned for its ability to remain functional at a wide range of temperatures. The Kapton was then cut, kirigami-style, using a laser cutter. Because the polymeric Kapton stretches easily, only a small energetic input is needed to generate significant movement of the panels. According to the team’s research, the power generation of their prototype tracking solar cells was 36% greater than that of standard immobile flat solar panels, nearly on par with single-axis rotating cells. Unlike the single-axis rotators, however, these new art-inspired panels can be installed with exactly the same tools, expertise and cost as traditional panels making them a practical option for home use. Says Shtein, "We think it has significant potential, and we're actively pursuing realistic applications. It could ultimately reduce the cost of solar electricity."

Just another example of the technological breakthroughs that occur when the disparate worlds of art and science are allowed to mingle.

Via Phys.org and Nature Communications.