Stanford University researchers have used 3D printing to develop a new device that could help boost the energy-capturing capabilities of solar panels and remove the need for mechanized tracking systems.
Shaped like an inverted pyramid with no spike, the team’s AGILE (Axially Graded Index Lens) device captures more than 90 percent of the light it’s exposed to and channels it to triple its brightness. Compared to existing solar panels, which track the sun across the sky, the AGILE can also passively capture light from any angle, giving it the potential to make solar panels smaller, cheaper and more efficient. .
“We wanted to create something that captures light and focuses it in the same place, even when the source changes direction,” says Nina Vaidya, developer of the device. “It’s a completely passive system – it doesn’t need power to track the source or have any moving parts. Without optical focus shifting positions or the need for tracking systems, concentrating light becomes much simpler. »
Pursuing solar energy efficiency
Since the sunlight absorption capacities of photovoltaic systems depend on their direct orientation towards the sun, many are equipped with solar trackers. In a single axis configuration, these systems rotate back and forth in a single direction. With dual-axis trackers, on the other hand, they tend to use a mirror to redirect sunlight to a stationary receiver, to maximize light panel exposure.
Both of these “active” systems move in tandem with the sun and generate more power than stationary alternatives, but Stanford engineers say they’re also more expensive and more complicated to build. To facilitate more efficient capture of solar energy, the team therefore developed a device made from a material designed to passively focus scattered light into a focal point.
Known as AGILE, this device works like a magnifying glass, in that it concentrates the sun’s rays into a smaller, brighter spot, but instead of moving with the sun, it channels the sun’s rays into a smaller, brighter point. all angles to the same exit. By replacing the silicon used to encapsulate existing solar modules with a layer of these devices, the researchers say more power can be generated from compact, cheaper solar panels.
“The best solutions are often the simplest ideas,” explains Vaidya’s thesis supervisor, Olav Solgaard. “An ideal AGILE has, at the very front, the same refractive index as air and it gradually increases – the light bends into a perfectly smooth curve.” Although he adds, “in a practical situation, you’re not going to have that ideal AGILE.”
Agile Solar Energy Harvesting
In order to produce their first AGILE polymer lens prototypes in 2018, engineers used a combination of SLA and 3D wax printing. However, the team has since moved on to a method that allows the deposition of glass and polymer in a graded-index material, with layers able to change the direction of a light beam in steps, instead of one at a time. smooth curve.
Using this material, researchers have now succeeded in creating “mirror” devices, in which any light directed in the wrong direction is reflected back to their output. During testing, these prototypes also demonstrated their ability to channel light in such a way as to triple its brightness. As such, it is said that the devices could eventually be mounted on regular solar panels, to allow them to pick up light scattered by the Earth’s atmosphere, weather and seasons.
According to Vaidya, the main challenge in creating such devices is formulating the right material. The plastic and glass used to make the team’s prototypes had to be compatible with each other, as if one expanded in response to heat at a different rate than the other, the whole device could crack. That said, the team eventually found a formula that allows for the creation of lenses with nanoscale characteristics, giving it solar panel storage and backlit display power potential.
“Being able to use these new materials, these new manufacturing techniques and this new AGILE concept to create better solar concentrators has been very rewarding,” concludes Vaidya. “Abundant and affordable clean energy is a critical component to addressing pressing climate and sustainability challenges, and we must catalyze engineered solutions to make it a reality.”
“Using our efforts and knowledge to create meaningful engineering systems has been my driving force, even when some trials didn’t work.”
Advancing Solar Energy Storage
A significant amount of research is currently devoted to 3D printable materials with enhanced solar energy storage capabilities. Earlier this year, Oak Ridge National Laboratory (ORNL) announced that a team of its researchers is investigating the potential of metal halide perovskites for 3D printing high-performance solar batteries.
Similarly, the start-up T3DP has already experimented with using its patented technologies to 3D print perovskite-based solar panels. Inspired by an exact replica of a fly’s eye, the company’s copper-plated hexagonal scaffolding is said to be able to harness twice as much energy as conventional solar panels.
Elsewhere, the technology has also been deployed to enable the creation of solar-powered devices with applications other than clean energy generation. Researchers based in China and Singapore, for example, have 3D-printed solar water purification devices at such a high standard in the past that they have passed World Health Organization standards.
The researchers’ findings are detailed in their paper titled “3D printed optics with nanoscale surface roughnesswhich was co-written by Nina Vaidya and Olav Solgaard.
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The featured image shows Nina Vaidya measuring the experimental performance of optical concentrators under a solar simulator. Photo via Nina Vaidya.