Tag Archives: solar panels

Optical Circuits Up To 100 Times Faster Than Electronic Circuits

Optical circuits are set to revolutionize the performance of many devices. Not only are they 10 to 100 times faster than electronic circuits, but they also consume a lot less power. Within these circuits, light waves are controlled by extremely thin surfaces called metasurfaces that concentrate the waves and guide them as needed. The metasurfaces contain regularly spaced nanoparticles that can modulate electromagnetic waves over sub-micrometer wavelength scales.

Metasurfaces could enable engineers to make flexible and ultra-thin optics for a host of applications, ranging from flexible tablet computers to solar panels with enhanced light-absorption characteristics. They could also be used to create flexible sensors for direct placement on a patient’s skin, for example, in order to measure things like pulse and blood pressure or to detect specific chemical compounds.

The catch is that creating metasurfaces using the conventional method, lithography, is a fastidious process that takes several hours and must be done in a cleanroom. But EPFL engineers from the Laboratory of Photonic Materials and Fiber Devices (FIMAP) in Switzerland have now developed a simple method for making them in just a few minutes at low temperatures—or sometimes even at room temperature—with no need for a cleanroom. The EPFL‘s School of Engineering method produces dielectric glass metasurfaces that can be either rigid or flexible. The results of their research appear in Nature Nanotechnology.

The new method employs a natural process already used in : dewetting. This occurs when a thin film of material is deposited on a substrate and then heated. The heat causes the film to retract and break apart into tiny nanoparticles.

Dewetting is seen as a problem in manufacturing—but we decided to use it to our advantage,” says Fabien Sorin, the study’s lead author and the head of FIMAP.

With their method, the engineers were able to create dielectric glass metasurfaces, rather than metallic metasurfaces, for the first time. The advantage of dielectric metasurfaces is that they absorb very little light and have a high refractive index, making it possible to modulate the light that propagates through them.

Source: https://phys.org/

Invisible Plastic For Super Efficient Solar Panels

Antireflection (AR) coatings on plastics have a multitude of practical applications, including glare reduction on eyeglasses, computer monitors and the display on your smart-phone when outdoors. Now, researchers at Penn State have developed an AR coating that improves on existing coatings to the extent that it can make transparent plastics, such as Plexiglas, virtually invisible.

Plastic dome coated with a new antireflection coating (right), and uncoated dome (left)

This discovery came about as we were trying to make higher-efficiency solar panels,” said Chris Giebink, associate professor of electrical engineering, Penn State. “Our approach involved concentrating light onto small, high-efficiency solar cells using plastic lenses, and we needed to minimize their reflection loss.”

They needed an antireflection coating that worked well over the entire solar spectrum and at multiple angles as the sun crossed the sky. They also needed a coating that could stand up to weather over long periods of time outdoors. “We would have liked to find an off-the-shelf solution, but there wasn’t one that met our performance requirements,” he said. “So, we started looking for our own solution.”

That was a tall order. Although it is comparatively easy to make a coating that will eliminate reflection at a particular wavelength or in a particular direction, one that could fit all their criteria did not exist. For instance, eyeglass AR coatings are targeted to the narrow visible portion of the spectrum. But the solar spectrum is about five times as broad as the visible spectrum, so such a coating would not perform well for a concentrating solar cell system.

Reflections occur when light travels from one medium, such as air, into a second medium, in this case plastic. If the difference in their refractive index, which specifies how fast light travels in a particular material, is large — air has a refractive index of 1 and plastic 1.5 — then there will be a lot of reflection. The lowest index for a natural coating material such as magnesium fluoride or Teflon is about 1.3. The refractive index can be graded — slowly varied — between 1.3 and 1.5 by blending different materials, but the gap between 1.3 and 1 remains.

In a paper recently posted online ahead of print in the journal Nano Letters, Giebink and coauthors describe a new process to bridge the gap between Teflon and air. They used a sacrificial molecule to create nanoscale pores in evaporated Teflon, thereby creating a graded index Teflon-air film that fools light into seeing a smooth transition from 1 to 1.5, eliminating essentially all reflections.

The interesting thing about Teflon, which is a polymer, is when you heat it up in a crucible, the large polymer chains cleave into smaller fragments that are small enough to volatize and send up a vapor flux. When these land on a substrate they can repolymerize and form Teflon,” Giebink explained.

 

We’ve been interacting with a number of companies that are looking for improved antireflection coatings for plastic, and some of the applications have been surprising,” he said. “They range from eliminating glare from the plastic domes that protect security cameras to eliminating stray reflections inside virtual/augmented -reality headsets.”

Source: https://news.psu.edu/

Perovskite Solar Panels Go To The Market

Across the globe, a clutch of companies from Oxford, England to Redwood City, Calif. are working to commercialize a new solar technology that could further boost the adoption of renewable energy generation. Earlier this year, Oxford PV, a startup working in tandem with Oxford Universityreceived $3 million from the U.K. government to develop the technology, which uses a new kind of material to make solar cells. Two days ago, in the U.S., a company called Swift Solar raised $7 million to bring the same technology to marketaccording to a filing with the Securities and Exchange Commission.

Called a perovskite cell, the new photovoltaic tech uses hybrid organic-inorganic lead or tin halide-based material as the light-harvesting active layer. It’s the first new technology to come along in years to offer the promise of better efficiency in the conversion of light to electric power at a lower cost than existing technologies.

Perovskite has let us truly rethink what we can do with the silicon-based solar panels we see on roofs today,” said Sam Stranks, the lead scientific advisor and one of the co-founders of Swift Solar, in a Ted Talk. “Another aspect that really excites me: how cheaply these can be made. These thin crystalline films are made by mixing two inexpensive readily abundant salts to make an ink that can be deposited in many different ways… This means that perovskite solar panels could cost less than half of their silicon counterparts.”

First incorporated into solar cells by Japanese researchers in 2009, the perovskite solar cells suffered from low efficiencies and lacked stability to be broadly used in manufacturing. But over the past nine years researchers have steadily improved both the stability of the compounds used and the efficiency that these solar cells generate.

Oxford PV, in the U.K., is now working on developing solar cells that could achieve conversion efficiencies of 37 percentmuch higher than existing polycrystalline photovoltaic or thin-film solar cells.

New chemistries for solar cell manufacturing have been touted in the past, but cost has been an obstacle to commercial rollout, given how cheaply solar panels became thanks in part to a massive push from the Chinese government to increase manufacturing capacity.

Source: https://techcrunch.com/

Blinds Harness The Sun’s Energy

Solargaps, an Ukrainian startup, have created blinds that generate power from windows.

If, like many Kyivans (inhabitants of Kiev), you live in an apartment, and your home doesn’t even have its own roof, there is now a solution. Enter Ukrainian startup SolarGaps, which has created a device that combines solar panels with venetian blinds to allow those who live in apartments to generate their own electricity.

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It’s not simple to install solar panels on roofs in big cities,” founder Evgeny Eric, 39, told the Kyiv Post. “Our solution helps people produce green energy more easily, cheaply and more accessibly.
Once installed on a window, the smart blinds with built-in solar panels can generate over 100 kilowatt of energy a month – the average amount of energy consumed monthly by one Ukrainian citizen, Eric said.

Any energy surplus can either be stored in batteries or be sold to the electricity company as green energy – for a higher price – although to do this a two-way electricity meter has to be installed by the local electricity provider.

To absorb as much solar radiation as possible, the panels, which are equipped with a light sensor, follow the light source, automatically changing angle according to the sun’s position. So that a room is bright enough during the day, the blinds automatically open when a person enters the room where they are installed. They also can be controlled via a smartphone application that currently connects to the device via Bluetooth. The latest app version will link to the device via the internet, using Android and iOS smartphones. The first prototype was created six months ago and installed in Eric’s apartment.

You just plug the blinds into a socket and they compensate for a part of your electricity consumption, that’s it,” Eric said. “We worked out this solution for ourselves, and now we’re offering it to others.

Source: https://solargaps.com/

Mass Production of Low-Cost Solar Cells

An international team of university researchers today reports solving a major fabrication challenge for perovskite cells — the intriguing potential challengers to silicon-based solar cells.

These crystalline structures show great promise because they can absorb almost all wavelengths of light. Perovskite solar cells are already commercialized on a small scale, but recent vast improvements in their power conversion efficiency (PCE) are driving interest in using them as low-cost alternatives for solar panels.

In the cover article published online in Nanoscale, a publication of the Royal Society of Chemistry, the research team reveals a new scalable means of applying a critical component to perovskite cells to solve some major fabrication challenges. The researchers were able to apply the critical electron transport layer (ETL) in perovskite photovoltaic cells in a new way — spray coating — to imbue the ETL with superior conductivity and a strong interface with its neighbor, the perovskite layer.

The researchers turned to spray coating, which applies the ETL uniformly across a large area and is suitable for manufacturing large solar panels. They reported a 30 percent efficiency gain over other ETLs – from a PCE of 13 percent to over 17 percent – and fewer defects.

Added Taylor, “Our approach is concise, highly reproducible, and scalable. It suggests that spray coating the PCBM ETL could have broad appeal toward improving the efficiency baseline of perovskite solar cells and providing an ideal platform for record-breaking p-i-n perovskite solar cells in the near future.”

The research is led by André D. Taylor, an associate professor in the NYU Tandon School of Engineering’s Chemical and Biomolecular Engineering Department, with Yifan Zheng, the first author on the paper and a Peking University researcher. Co-authors are from the University of Electronic Science and Technology of China, Yale University, and Johns Hopkins University.

Source: https://engineering.nyu.edu/