According to a university press release, Stanford University researchers have developed a new optical concentrator that can receive even dimmed light in a fixed position, increasing solar panels' power generation capability.
Photovoltaic cells operate best when sunlight is reflected directly on them. Scientists have relied on solar tracking to keep panels in sync with the Sun as it travels across the sky. However, installing these systems increases the cost of deploying solar panels at a significant scale.
A possible solution to this problem would be to place a magnifying glass above the panels that might concentrate the sunlight to a single point. However, the moving Sun would result in the concentrated spot also moving across the panels, causing the solar panel design to be hampered once more.
Stanford's approach to the problem
Nina Vaidya, a Stanford University professor, has developed an elegant gadget that can concentrate light that falls on it from any angle and at any frequency and then direct it to a single point on the panel.
In the press release, the device is named Axially Graded Index Lens (AGILE) but it is nothing more than a glass pyramid in an inverted position. "Its a completely passive system it doesnt need energy to track the source or have any moving parts," said Vaidya.
Vaidya theorized that an engineered material with a smoothly increasing refractive index might bend incoming light and direct it to a single point. The refractive index is a measure of how quickly light travels through a material.
Converting theory to reality
The researchers used a wide variety of materials to fabricate their device that had a graded refractive index. The prototypes also had mirrors on their sides so that any light that would escape would be sent right back. Using a variety of materials also had the disadvantage of cracking the device.
Vaidya's previous 3D printing experience came in handy when she produced nanometer-scale glass. Using new fabrication techniques, the researchers were able to 3D print AGILE using commercially available polymers and glasses.
Researchers captured 90% of light that reflected onto the AGILE surface, and created spots that were three times brighter than the incident light. The lens works with a wide spectrum of light, from ultraviolet to infrared, as well as light that is reflected due to weather conditions or atmospheric conditions.
According to the press release, a layer of AGILE installed on solar panels might help in the removal of existing protective layers, but also provide space for cooling and electrical connections between the inverted pyramids.
Solar panels have just become even more appealing.
The findings of the study have been published in the journal Microsystems and Nanoengineering.
Immersion optics allow for improved optical concentration and coupling by taking advantage of the fact that the luminance of light is proportional to the square of the refractive index in a lossless optical system. We describe theoretical, simulations, and experiments for designing various immersion graded index optics suitable for various applications, including high optical concentration, refractive index, height, and efficiency. We demonstrate that graded-index-lens concentrators perform well below the theoretical limit and employ simple, cost-effective, design-flex