A stack of tiny lenses that look like inverted pyramids could fill the solar cells, helping them capture more light from any angle on sunny and cloudy days.
Solar panels perform best in direct sunlight, so some solar systems follow a large fireball across the sky and face it for maximum light. Unfortunately, such tracking technology is expensive and moving parts can break.
Shortcomings like these have prompted researchers at Stanford to develop an alternative. The resulting technology – called Axially Graded Index Lens, or AGILE for short – offers a way to increase the efficiency of static solar panels, even in diffuse light, authors Nina Vaidya and Olav Solgaard said in peer reviewed article. pAGILE rototype lens arrays successfully concentrated light into an area 3 times smaller, retaining 90% of their power at best and well ahead of more rudimentary concentrators when the light was more oblique (sometimes concentrators can sacrifice light intensity but come out before the collection angle).
Concentrating light to squeeze more energy out of solar panels is nothing new, but the authors point out that concentrators such as Fresnel lenses and mirrors only provide “modest acceptable angles.” By the way, the pyramid design also looks glamorous in the rendering video posted alongside the paper.
The AGILE lens prototype is shown in three stages of development. A: Laminated glass. B: With aluminum sides. C: With a solar cell that absorbs light. Image Credits: Nina Vaidya
The internet is full of great ideas that could help us capture more of the sun’s energy. Many are inspired by things in nature such as butterfly wings, fly eyes, flower petals and even puffer fish. The design for AGILE “did not emerge from nature,” says Vaidya, but the paper acknowledges that “there are features of AGILE that can be found in the retina of fish (e.g., Gnathonemus) and compound eyes of insects (e.g., Lepidoptera), where the gradient index present as a counter-reflection to maximize transmission and enable camouflage.”
Although the researchers have not announced any plans to commercialize AGILE, the prototypes were designed with the solar industry in mind, using readily available materials, according to a Stanford press release.
“Abundant and affordable clean energy is a key part of addressing urgent climate and sustainability challenges,” Vaidya said. “We need to catalyze engineering solutions to make it happen.”