Tag Archives: Solar-Cells

Commercial ‘Green’ Solar Cells May Be Possible, Say Pitt Researchers

PITTSBURGH—Developing solar energy that is low-cost, lightweight, and energy efficient has proven to be one of the greatest challenges the science world faces today. Although current plastic solar cells are low in cost and easy to produce, they are not energy efficient and, therefore, not easily commercialized. With grant funding from the National Science Foundation, researchers at the University of Pittsburgh are predicting a way to produce solar cells that will offer more flexibility in generating green energy.

Guangyoung Li, assistant professor of electrical and computer engineering at Pitt, explains that most plastic solar cells today are made from a blend of semiconducting polymers and other carbon-rich molecules. Although this material is usable and costs little, it does not assist with energy efficiency—though it could. Li’s solution is to use a method called Kelvin Probe Force Microscopy (KPFM) that studies the surface potential of cells through microscopy. Although KPFM is not a new idea, Li plans on using it in a dramatically different way.

“The problem with traditional force microscopy is that the resolution is not good enough, so we can’t properly study the domains we need to examine,” says Li. “Throughout my research, I will work to develop an instrument that will be better able to detect the domains formed from different materials.”

This instrument could help Li and others explain the conditions that plastic solar cells should have for better energy efficiency. Currently, plastic solar cells have achieved an energy efficiency rate of 8.6 percent. Li says if he can produce solar cells with a 10 percent or higher efficiency rate, they would have a broad impact on the energy market.

“In the future, I can imagine this new, efficient material anywhere—on buildings, roofs, you name it,” said Li. “You could charge your laptop, cellphone, or iPod simply by having a charger on you and stepping into sunlight.”

Li notes this research will not only help reduce energy consumption, but also will help train young scientists, including the undergraduate and graduate students from underrepresented areas involved in the project. He also notes it is an “ideal platform” to teach the greater community, specifically K-12 students, teachers, industry leaders, and the general public.

SiOnyx Solar Achieves Record Results for Black Silicon Solar Cells

Beverly, Mass. – October 25, 2011 – SiOnyx, Inc today announced that its patented ultrafast laser texturing technology known as Black Silicon has achieved a 0.3% (absolute) efficiency boost over industry-standard baseline solar cells.  The SiOnyx 156 mm multicrystalline silicon cells, made in collaboration with German research institute ISC Konstanz, achieved average absolute efficiencies of over 17%.

Importantly, SiOnyx Black Silicon boosts efficiency in thinner wafers, vital for reducing the cost of silicon-based solar cells.  Average efficiencies of 16.9% were achieved for 150-micron thick multicrystalline cells that are 20% thinner than wafers in production today and represent a cost reduction of 10-15%.  All cells were processed and tested at ISC Konstanz using a standard emitter, screen-printed metal, and aluminum back surface field.  Black Silicon texturing was performed using a Coherent AethonTM tool with a TaliskerTM picosecond laser.

Additionally, the SiOnyx process results in a significant improvement in process uniformity.  Standard deviations for cell efficiency and current are reduced by a factor of two using SiOnyx’s Black Silicon, resulting in further cost reductions through improved process yield and tighter efficiency binning.

“These results are further validation of the Black Silicon process and its ability to improve the economics of mainstream solar energy – and the technology is ready now,” commented Stephen Saylor, President and CEO of SiOnyx.  “SiOnyx’s single-sided texture achieves significantly lower surface reflectance than industry-standard isotexture to improve cell performance. We boost infrared performance, thus making SiOnyx Black Silicon a great complement to existing selective emitter technologies.”

SiOnyx Black Silicon is a drop-in solution for the majority of solar cell lines using industry standard isotexture and is critical in supporting roadmap architectures requiring a planar back surface for dielectric passivation.  SiOnyx Black Silicon is completely independent of grain orientation and therefore ideal for all wafer types including multicrystalline. By decoupling the saw damage removal and surface texturing steps, the SiOnyx process is the perfect solution for manufacturers seeking to improve both the price and performance of existing lines while establishing a roadmap for next-generation cells using backside passivation with local contacts.

For additional product and licensing information please contact SiOnyx Solar at solarbizdev@sionyx.com

About SiOnyx
SiOnyx (www.sionyx.com) is commercializing a patented semiconductor process known as Black Silicon that dramatically enhances the infrared sensitivity of silicon-based photonics. As a result, SiOnyx’s Black Silicon platform represents a significant breakthrough in the development of smaller, cheaper, higher performance photonic devices. SiOnyx Solar is focused on next generation photovoltaic applications. SiOnyx Imaging is developing advanced digital imaging solutions for consumer, industrial, medical, and defense applications. Additional information about SiOnyx Solar is available at www.sionyx.com/solar.

Solar3D Inc developing new three-dimensional solar cell technology to maximize conversion of sunlight into electricity

Solar3D Inc. (OTCBB:SLTD), based in Santa Barbara, Calif., is developing a breakthrough new three-dimensional solar cell technology to maximize the conversion of sunlight into electricity. Solar3D’s technology is expected to increase the efficiency of solar cells by 50 to 100 percent.

The sun floods the earth with enough solar energy in one hour to power the entire world. But despite the dramatic growth of the solar industry, solar electricity accounts for less than 1 percent of global electricity generation. The reason is that solar cells still cost too much to produce. The practical efficiency of crystalline silicon solar cells ranges from 15 to 19 percent, meaning that such cells harvest only a fraction of the sun’s energy. In order to power the world, solar cells must be able to convert more sunlight into electricity at a lower cost.

Solar3D’s breakthrough technology uses low-cost processes to increase the efficiency of solar cells in order to decrease the overall cost per watt of electricity. Our revolutionary solar cell engineering approach tips the solar cost curve in the direction of massive scalability, thus allowing the global deployment of a non-polluting energy technology that produces electricity from an unlimited source of power. Moreover, unlike fossil fuels, whose supplies are limited, the sun is expected to continue to burn brightly for another five billion years or more.

Almost all conventional solar cells are two-dimensional. Up to 30 percent of incident sunlight is reflected off the surface, and more is lost inside the solar cell materials. By contrast, the Solar3D design uses an array of light-collecting elements that guide the sunlight into a corresponding array of three-dimensional, micro-photovoltaic structures. These have been described as resembling a collection of miniature towers in an urban street grid. The sunlight, in the form of photons, is trapped among these micro-structures, where it bounces around until it is converted into electricity.

The Solar3D technology also results in reduced loss of photons inside the solar cell. Solar cells generate electricity through the photovoltaic effect, in which sunlight triggers the release of electrons from their atoms, resulting in the creation of an electric current. Because the Solar3D technology absorbs more photons, the solar cell coating doesn’t need to be as thick, which means that the excited electrons spend less time in the semiconductor material, reducing the possibility that they will be reabsorbed — a major cause of poor performance in solar cells.

Finally, the Solar3D design’s network of contact wires runs below the light collectors instead of on top as in a conventional solar cell, where they block sunlight. Solar3D’s cells are thus able to trap and utilize nearly all of the incident light.

The solar industry grew at a compound annual rate of 35 percent between 2000 and 2009, despite the global recession. The industry generated $38.5 billion in revenues in 2009 and is expected to generate revenues of $100 billion in 2014. Despite this growth potential, however, the widespread deployment of solar is still limited by cost. Many industry experts thought thin-film technology would address this problem. But although thin film is cheaper, it is also less efficient, with more thin-film panels required to produce the same output of electricity.

Solar3D’s three-dimensional technology combines thin- and thick-film technologies to achieve the high efficiencies of crystalline at the lower cost per watt of thin film. The Solar3D technology is expected to improve the efficiency of solar cells by 50 to 100 percent, thus maximizing the efficiency of any solar material. Although Solar3D’s initial commercialization objective is focused on silicon solar cells, the technology is “material agnostic,” meaning that it can also be used with exotic materials such as gallium arsenide for high performance applications.

The development of Solar3D’s innovative technology will enable the solar industry to achieve or exceed the goal of grid parity, which is the price at which electricity produced from solar energy is competitive with that of electricity produced from traditional energy sources such as coal or gas. Solar3D expects to have a prototype ready by the end of 2011 and to be in production within a year of that. The technology is also production friendly, meaning that its manufacture will require no new fabrication techniques; it can be produced by existing manufacturing facilities.

The history of technological development is one in which the introduction of a new technology such as the automobile or the computer is followed by decades of improvements — many of them highly innovative in nature — that bring down the cost to the point that the technology enters the mainstream. The solar cell is no different: first invented in 1883, the solar cell is finally is poised to replace traditional energy sources on a large scale thanks to Solar3D’s new technology, which is reengineering the solar cell to make it more efficient and less costly.

Solar3D is proud to be at the forefront of a low-cost “next generation” solar technology that will bring convenience, prosperity and comfort to the world powered by an energy source that will never run out, as long as the sun continues to shine.

New Freeloader Solar Charger Puts the Power of the Sun in Your Hands

Gloucestershire, UK – In today’s society, it’s virtually impossible to go a day without use of a cell-phone, MP3 player, or digital camera. With that dependence on hand-held technology and lifestyles that are becoming increasingly on-the-go, a dead battery is a very real nuisance and searching for an outlet to recharge can be an insurmountable burden. Recognizing the demand for convenient and affordable power sources, Solar Technology International is launching its line of Freeloader Solar Chargers, which harness the power of the sun, in the United States.

By channeling power to Li-ion batteries through its solar panels, the Freeloader Solar Chargers are able to reliably power any hand-held device anywhere, anytime—essentially freeloading power from the Sun.  Solar Technology International offers three different versions of the Freeloader, all of them providing a sleek, compact design along with an environmentally conscious mentality.

“Being able to free load the energy from the sun, and use that to power all of the gadgets that we use day-today; that is our vision,” says Adrian Williams, President of Solar Technology International.  “We provide that with the Freeloader.  It’s something that everyone from techies to greenies to anyone who is constantly on the go can appreciate.”

New to the US, the standard Freeloader appears as a stylish aluminum body the size of a cellular phone. Utilizing two 120mA solar cells, the standard Freeloader can charge the 1000mA lithium-ion battery in as little as eight hours. The standard Freeloader can power an iPod for 18 hours, a mobile phone for 44 hours, a PSP for 2.5 hours, a PDA for 22 hours and much more. MSRP $59.99 USD.

New for the worldwide marketplace, and designed to provide free and infinite power to almost all portable electronic devices, the FreeLoader Pro is the perfect eco-friendly, pocket sized partner for an endless array of gadgets such as mobile/smartphones (including the iPhone and Blackberry), mobile gaming devices, MP3 players, GPS devices, e-books, PDAs, and more.  Included with the Freeloader PRO is the CamCaddy accessory, which gives the Freeloader PRO the unique ability to charge compact digital, DSLR and video camera batteries. The Freeloader PRO uses two 200mA solar cells to power a 1600mAh lithium-ion battery which can provide a mobile phone with 70 hours of standby time, 5,000 page turns on an eBook, or fully charge a digital camera battery.  MSRP $119.99 USD

Also completely new for the worldwide market, the Freeloader PICO is the ideal travel buddy for virtually any portable electronic device.  Boasting an extremely lightweight and tiny design, the Freeloader PICO can provide enough power to keep a mobile phone running for 35 hours or an iPod for 14 hours. When fully charged, the PICO will charge a gadget in just 30 minutes using one 75mA solar panel which powers an 800mA li-ion battery. MSRP $29.99 USD

The Freeloader Solar Chargers are currently available for purchase at www.freeloadersolar.com and will be at select retailers nationwide starting May 1, 2010.

About Solar Technology International

Solar Technology International designs and produces a range of solar products that allows users to harness solar energy. The solar panels capture the sun’s energy and convert it to electrical current to power a range of appliances.  Solar Technology’s panels use Crystalline silicon technology, the latest in solar technology to harness power which is more efficient than amorphous or thin film solutions, particularly in lower light conditions.  To find out more about Solar Technology’s product range, please visit: www.freeloadersolar.com

Caltech Researchers Create Highly Absorbing, Flexible Solar Cells with Silicon Wire Arrays

PASADENA, Calif. (2/14/10) Using arrays of long, thin silicon wires embedded in a polymer substrate, a team of scientists from the California Institute of Technology (Caltech) has created a new type of flexible solar cell that enhances the absorption of sunlight and efficiently converts its photons into electrons. The solar cell does all this using only a fraction of the expensive semiconductor materials required by conventional solar cells.

“These solar cells have, for the first time, surpassed the conventional light-trapping limit for absorbing materials,” says Harry Atwater, Howard Hughes Professor, professor of applied physics and materials science, and director of Caltech’s Resnick Institute, which focuses on sustainability research.

The light-trapping limit of a material refers to how much sunlight it is able to absorb. The silicon-wire arrays absorb up to 96 percent of incident sunlight at a single wavelength and 85 percent of total collectible sunlight. “We’ve surpassed previous optical microstructures developed to trap light,” he says.

Atwater and his colleagues—including Nathan Lewis, the George L. Argyros Professor and professor of chemistry at Caltech, and graduate student Michael Kelzenberg—assessed the performance of these arrays in a paper appearing in the February 14 advance online edition of the journal Nature Materials.

Atwater notes that the solar cells’ enhanced absorption is “useful absorption.”

“Many materials can absorb light quite well but not generate electricity—like, for instance, black paint,” he explains. “What’s most important in a solar cell is whether that absorption leads to the creation of charge carriers.”

The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons—in technical terms, the wires have a near-perfect internal quantum efficiency. “High absorption plus good conversion makes for a high-quality solar cell,” says Atwater. “It’s an important advance.”

The key to the success of these solar cells is their silicon wires, each of which, says Atwater, “is independently a high-efficiency, high-quality solar cell.” When brought together in an array, however, they’re even more effective, because they interact to increase the cell’s ability to absorb light.

“Light comes into each wire, and a portion is absorbed and another portion scatters. The collective scattering interactions between the wires makes the array very absorbing,” he says.

This effect occurs despite the sparseness of the wires in the array—they cover only between 2 and 10 percent of the cell’s surface area.

“When we first considered silicon wire-array solar cells, we assumed that sunlight would be wasted on the space between wires,” explains Kelzenberg. “So our initial plan was to grow the wires as close together as possible. But when we started quantifying their absorption, we realized that more light could be absorbed than predicted by the wire-packing fraction alone. By developing light-trapping techniques for relatively sparse wire arrays, not only did we achieve suitable absorption, we also demonstrated effective optical concentration—an exciting prospect for further enhancing the efficiency of silicon-wire-array solar cells.”

Each wire measures between 30 and 100 microns in length and only 1 micron in diameter. “The entire thickness of the array is the length of the wire,” notes Atwater. “But in terms of area or volume, just 2 percent of it is silicon, and 98 percent is polymer.”

In other words, while these arrays have the thickness of a conventional crystalline solar cell, their volume is equivalent to that of a two-micron-thick film.

Since the silicon material is an expensive component of a conventional solar cell, a cell that requires just one-fiftieth of the amount of this semiconductor will be much cheaper to produce.

The composite nature of these solar cells, Atwater adds, means that they are also flexible. “Having these be complete flexible sheets of material ends up being important,” he says, “because flexible thin films can be manufactured in a roll-to-roll process, an inherently lower-cost process than one that involves brittle wafers, like those used to make conventional solar cells.”

Atwater, Lewis, and their colleagues had earlier demonstrated that it was possible to create these innovative solar cells. “They were visually striking,” says Atwater. “But it wasn’t until now that we could show that they are both highly efficient at carrier collection and highly absorbing.”

The next steps, Atwater says, are to increase the operating voltage and the overall size of the solar cell. “The structures we’ve made are square centimeters in size,” he explains. “We’re now scaling up to make cells that will be hundreds of square centimeters—the size of a normal cell.”

Atwater says that the team is already “on its way” to showing that large-area cells work just as well as these smaller versions.

In addition to Atwater, Lewis, and Kelzenberg, the all-Caltech coauthors on the Nature Materials paper, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” are postdoctoral scholars Shannon Boettcher and Joshua Spurgeon; undergraduate student Jan Petykiewicz; and graduate students Daniel Turner-Evans, Morgan Putnam, Emily Warren, and Ryan Briggs.

Their research was supported by BP and the Energy Frontier Research Center program of the Department of Energy, and made use of facilities supported by the Center for Science and Engineering of Materials, a National Science Foundation Materials Research Science and Engineering Center at Caltech. In addition, Boettcher received fellowship support from the Kavli Neuroscience Institute at Caltech.

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Visit the Caltech Media Relations website at http://media.caltech.edu

‘Silicon ink’ for solar cells glides toward production

By Candace Lombardi, news.cnet.com
Innovalight JA Solar, one of the big players in the solar industry, is working  with Innovalight to commercialize the latter’s method for making silicon-ink-based, high-efficiency solar cells, the companies said this week.

Innovalight first got noticed in 2007 for perfecting a process in which it could essentially ink-jet-manufacture solar cells using a proprietary silicon ink it had developed. The solar cells are created by pouring an ink solution incorporated with silicon nanoparticles and then decanting the excess liquid to leave behind a crystalline silicon structure.

At the time of the 2007 announcement, Sunnyvale, Calif.-based Innovalight claimed its method not only resulted in solar cells that were cheaper to produce by as much as half, but that the crystalline structure resulting from the process made its cells more efficient at converting electricity.

Those claims now appear to be validated.

On Tuesday, Innovalight announced that an independent study of its method by the U.S. Department of Energy’s National Renewable Energy Laboratory and the Fraunhofer Institute for Solar Energy Systems in Germany confirmed that its silicon ink-based cells “demonstrated a record 18 percent conversion of efficiency.”

Shanghai, China-based JA Solar said the process will lower its production cost for this type of solar cell.

“Innovalight’s silicon ink in conjunction with JA Solar’s leadership in high-volume solar cell manufacturing with demonstrated yield, conversion efficiency, and low production costs, provides a very promising solution to enhance the conversion efficiency of solar cells utilizing our existing solar cell manufacturing lines,” Qingtang Jiang, JA Solar’s chief technology officer, said in a statement Tuesday.

JA Solar plans to further develop the process at its research and development plant in Yangzhou, a city on China’s coast about 630 miles south of Beijing.

Dye-sensitized Solar Cells To Power Air Force Unmanned Aerial Vehicles

From ScienceDaily.com

Dye-sensitized solar cells (DSSCs) are expected to power Air Force unmanned aerial vehicles (UAVs) in the future because they are an optimum energy harvesting source that may lead to longer flight times without refueling.

The University of Washington’s Multidisciplinary University Research Initiative (MURI) project team, with lead researcher Dr. Minoru Taya is working on airborne solar cells by using a flexible film and a thin glass coating with transparent conductive electrodes. He has found that DSSCs made from organic materials, which use (dyes) and moth-eye film, are able to catch photons and convert them into synthesized electrons that can harvest high photon energy.

A few years ago the team mounted dye-sensitized solar cells on the wings of a toy airplane. The propeller was effectively powered, but the plane was not able to become airborne because the glass based solar cells they were using were too heavy. Upon experimentation, they decided to use film battery technology, which worked and in fact, enabled the plane to fly.

“These kinds of solar cells have more specific power convergence efficiency (PCE), very clean energy and easy scalability to a larger skin area of the craft, as well as, low-temperature processing, which leads to lower costs overall,” said Taya.

The team is currently working on DSSCs with higher PCEs using bioinspired dyes, which are installed in the wings of the UAV (airborne energy harvesters).

“Any airborne energy harvester must satisfy additional requirements, like weight and durability in airborne environments. If those are met, then there may even be longer UAV flight times,” said Taya.

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