It's long been known that solar tracking systems are able to harness more of the sun's energy than traditional fixed systems -- a whopping 40 percent more -- but while the bulky tracking panels do well in in spacious fields, they're not well-suited for rooftops. Conventional motorized trackers are heavy and most roofs, particularly residential ones are unable to support them.
That's an issue because 85 percent of solar installations in the U.S. are rooftop installations. So far, the focus has been on installing solar panels on the parts of the roof that get the most amount of sun during the day, but researchers at University of Michigan have come up with something far better: solar cells that track the sun while the panel they're installed on remains flat.
These new solar cells were inspired by the Japanese art of paper cutting called kirigami and are able to tilt within a larger flat panel, keeping their surfaces more perpendicular to the sun’s rays. This means that these solar cells could be installed anywhere that conventional panels can go like rooftops or even vehicle surfaces, but have the benefit of capturing more of 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, an 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 started out with actual paper to come up with a design and then moved on to Kapton, a space-grade plastic that they cut with a carbon dioxide laser. After experimenting, the simplest design won out: rows of dashes that allowed the plastic to pull apart into a basic mesh. Custom-made solar cells were then applied to Kapton and cut into the design. The more the mesh is stretched, the more the cells tilt, and this can be controlled within one degree.
You can see a demonstration of this below.
When the sun's rays come in at lower angles, the spreading and tilting of the cells ups the amount of sunlight being captured and turned into electricity.
The team actually hit a wall because there resources they had wouldn't allow them to make the optimum prototype in width and length, but they're looking for other options to fabricate it. The team was able to run their design through simulations and said that it offered a 36 percent improvement over a stationary panel.
The team published the results of its work in the journal Nature Communications and is already pursuing real-world applications for this technology.