Engineers from Stanford University (California, USA) They created an optical concentrator called Agile that helps solar systems capture more light even on a cloudy day and without having to point it directly at the Sun.
Researchers have successfully designed and tested this ingenious lensing device that can efficiently collect light from all angles and concentrate it to a fixed exit position.
Photovoltaic panels work best when sunlight is directly on them. To capture as much energy as possible, many solar panels actively rotate towards the Sun as they move across the sky. This makes them more efficient, but also more expensive and complex to build and maintain than a stationary system.
Nina Vaidya, an engineering researcher at Stanford University, It’s an ingenious device that can effectively collect and concentrate the light that hits it, whatever the angle and frequency of that light.
It is a completely passive system: it requires no power to monitor the source and has no moving parts. Concentrating light is much easier, as there is no need for position-dependent optical focus and tracking systems.
The device, called AGILE (Axial Graduated Index Lens), is simple in appearance. It looks like an inverted pyramid with a truncated tip. Light enters the frame, the top is tiled from any angle and funnels downward to create a brighter spot at the exit.
High system efficiency
Researchers in prototypes managed to capture more than 90% of the light striking the surface and create exit points three times brighter than incident light.
Installed on a panel above solar cells, these concentrators can make solar arrays more efficient and capture not only direct sunlight but also diffused light scattered into the atmosphere black.
Placing an AGILE hub layer over the panels can replace the existing encapsulation protecting solar arrays, eliminating the need to follow the Sun, creating space for cooling and circuitry between narrow pyramids of individual devices, and more importantly, reducing the amount of solar cell surface required to generate power, thereby reducing costs.
And the uses are not limited to ground-based solar installations: if applied to solar arrays sent into space, a layer AGILE can concentrate light and provide the necessary protection against radiation without sun tracking.
Same principle as a magnifying glass under the sun
basic premise AGILE is like using a magnifying glass to burn leaves using sunlight. The magnifying lens concentrates the sun’s rays in one spot.
But with a magnifying glass, the focal point moves like the sun does. Vaidya and Solgaard found a way to create a lens that receives rays from all angles but always concentrates the light at the same initial position.
Vaidya and Solgaard, in theory, It would be possible to collect and concentrate the scattered light using an engineering material that uniformly increases the refractive index., a property that describes how fast light travels through a material, causing the light to bend and bend toward a focal point. On the surface of the material, light bends with difficulty. By the time it reached the other side, it would be almost vertical and in focus.
An ideal AGILE has the same index of refraction as air in front and increases gradually: light bends in a perfectly smooth curve. But in a practical situation, this ideal AGILE would not exist.
For prototypes, The researchers layered different glasses and polymers that deflect light to varying degrees., creating what is known as graded directory material. The layers gradually change the direction of the light instead of a smooth curve, which the researchers say is a good approximation to ideal AGILE. The edges of the prototypes are mirrored, so any light going in the wrong direction is reflected back.
One of the biggest challenges was finding and creating the right materials. The material layers of the AGILE prototype allow a broad spectrum of light, from ultraviolet to near infrared, to pass through and deflect this light progressively towards the exit, with a wide range of refractive indices unseen in nature and today’s optics industry.
After discovering many materials, creating new manufacturing techniques, and testing multiple prototypes, the researchers AGILE designs that work well using commercially available polymers and glasses.
AGIL is also Made with 3D printing In the authors’ previous work creating lightweight, flexible engineered polymeric lenses with nanometer-scale surface roughness.
vaidya Hopes AGILE designs can be used in the solar industry and beyond. AGILE has a variety of potential applications in lighting such as laser coupling, imaging technologies, and solid-state lighting, which is more energy efficient than legacy lighting methods.
Reference Work: https://news.stanford.edu/2022/06/27/new-optical-device-help-solar-arrays-focus-light-even-clouds/
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