Sharp expands solar panels beyond silicon

Michael Kanellos

Sharp Electronics, one of the largest manufacturers of silicon solar panels, is experimenting with new materials. At the Solar Power 2006 Conference and Expo here, the company is showing off several prototype solar panels and a new system it hopes will increase efficiency and make it easier to install new solar systems. One prototype solar panel combines a tiny solar cell measuring about a quarter of an inch per side that sits beneath a Fresnel lens (a ridged lens originally used in lighthouses), which radically concentrates sunlight. Further improving its performance, the solar panel rotates with the sun.
   Boeing-Spectrolab has developed a solar cell that can convert almost 41 percent of the sunlight that strikes it into electricity, the latest step in trying to drop the cost of solar power.
   Potentially, the solar cell could bring the cost of solar power down to around $3 a watt, after installation costs and other expenses are factored in, over the life of the panel. The new cost information comes from Boeing, whose Spectrolab unit supplies searchlights and solar simulators, and the Department of Energy, which sponsored the project. Current silicon solar cells provide electricity at about $8 a watt, before government rebates. The goal is to bring it to $1 a watt without rebates or incentives. The cell achieves 40.7 percent efficiency. The Department of Energy has been sponsoring research to find ways to get solar cells past the so-called 40 percent barrier.
   Overall, Sharp says the panel can convert 36 percent of the sunlight that strikes it into electricity, far higher than the 13 to 22 percent conversion rates of commercial silicon solar cells. Sharp is the number one manufacturer of solar cells worldwide with nearly as much generating capacity as the next three largest manufacturers combined. Its residential solar systems give families the ability to generate their own electricity from the inexhaustible energy of the sun - with no harmful emissions. They're cost-effective, quiet, attractive, safe, and reliable, with only minimal maintenance required over their long operational life. They're the right choice for your home and the right choice for the environment. It's no wonder why so many homeowners are making the move to Sharp Solar.
   Imagine solar electricity not only powering businesses, large-scale utilities and neighbourhoods, but also billboards, streetlamps and portable electronics. Sharp's commitment towards environment-friendly products brings tomorrow's energy today.
   Sharp has also developed prototype solar cells that combine a layer of amorphous silicon and a layer of conventional, crystalline silicon, said Ron Kenedi, vice president of Sharp's solar-energy solutions group. These solar cells are nearly transparent, so they could potentially be used in windows. Sharp has installed some of these cells at its latest LCD (liquid crystal display) plant in Kameyama, Japan, which obtains much of its power through various "clean" energy sources.
   In another experiment, the company has inserted a layer of LED (light-emitting diode) lights between the two layers of the experimental combo cells. The solar cells power the LED lights, which can then light a room at night. Sharp is also experimenting with solar cells made from organic materials and different types of silicon.
   The experimentation arises from a belief that different types of panels will be required for different applications, said Kenedi.
   "You can't use the same product on the ground as on the roof. You have to have different weapons for each one of the wars," he said.
   
   Cheap and easy
   The solar panel with the concentrating lens is one example of a use-specific panel. This system, which may come to market in the next year or two, would be used for solar power plants--large installations in a field that would pass power onto the grid. These systems, for example, most likely would not be seen on suburban rooftops.
   The underlying solar cell, which converts sunlight to electricity, in these panels is made out of III-V compounds (molecules made from elements in the III and V columns of the Periodic Table of Elements). Producing chips from these materials, such as gallium arsenide, is expensive. Thus, the solar cell needs to be small. The lens, by contrast, is much less expensive and measures a few inches across. The panel itself measures about 12.5 feet by 16 feet and contains 270 lenses. Overall, a complete panel with 270 lenses can churn out 2.9 kilowatts and rotates with the sun for maximum efficiency.
   "The cell is expensive if you use it as it is," without the lens, acknowledged Kenedi, "but it will outperform traditional solar cells in the right conditions." The lens concentrates the energy to make it seem as if 700 suns are pointing at the solar cell, he added.
   Sharp is also producing equipment for conventional silicon solar panels. At the show, the company announced that it hopes to bring what it calls a solar racking system to the U.S. The system, which is already in use in Japan, essentially cuts down the time it takes to put a solar system on a roof by about 20 percent.
   On the consumer front, Sharp announced a partnership with Citibank that will let customers finance new solar systems through a home equity line of credit.
   
   Efficiency record
   Researchers at Lawrence Berkeley National Laboratories reported that cells made of a new type of semiconductor, zinc-manganese-tellurium, combined with a few atoms of oxygen, could convert around 45 percent of sunlight into electricity. That technology, also partly sponsored by the Department of Energy, has been licensed to RoseStreet Labs in Arizona. It remains to be seen whether this material can be made into solar cells economically.
   Sharp Solar, one of the biggest solar companies in the industry, showed a solar cell offering 36 percent efficiency earlier this year. The Sharp cell includes a concentrator--a thin lens that focuses sunlight on the cell--but is not made of silicon. It instead is made out of III-V compounds, molecules made from elements in the III and V columns of the periodic table of elements. (The metallic element gallium--used in semiconductors and optoelectronic devices--is from this neighborhood.)
   Currently, the best commercial silicon solar cells can convert 22 percent of the sunlight that hits them into electricity, and physics dictates that maximum efficiency for these cells will come at around 26 per cent.
   Boeing got around that barrier by integrating two technologies. One, the solar cell, contains a layer of concentrators. From a practical point of view, using a concentrator is like adding extra surface area to the cell.

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Infotech Desk

Graphics Tablet provides a means of converting two-dimensional information, such as maps and drawings, into computer-readable digitized form. It is very widely used in engineering and design applications. Computer graphics are now used in an increasing number of applications, ranging from the manipulation of highly detailed engineering drawings to computer games, from high definition views in aircraft simulators to automatic production of animated movie --- and indeed as an art form.
   Genius brand PenSketch 6x8 is a new design tool for professional artists who can increase their productivity with any professional publishing software. Using PenSketch 6x8 , one can draw and illustrate effortlessly. While processing images, the performance is more precise and more rapid. It also includes programmable "Hot-Cell" area for the office and Internet. One can use it with the pen device for super shortcuts. Price ranges from Tk.5,500 to 18,000 depending on models.
   Ipsita Computers, located at BCS Computer City in Dhaka, has made available a number of classy Genius products including the above device, says a press release. Professional designers and interested persons may call 9134983 or e-mail:ipsheeta@bdcom.com for details.
   The cordless pen of PenSketch 6x8 features two buttons and 1024 level pressure sensitivity. While drawing with the digital pen, it is possible to control all kinds of shapes and thickness easily. The two buttons of the pen can be programmed as the mouse left and right buttons. The pen-holder helps to store the digital pen and change the pen tip efficiently. The cordless mouse with scroll wheel gives more convenience when working on the tablet.
   Photoshop: PenSketch 6x8 makes it easy to quickly and professionally edit photos and create digital artwork by turning on the full power of Photoshop. Besides Photoshop, the PenSuite software including Annotate All, Annotate for Word, Pen Commander, PenMail, PenSigner and PenPresenter and provides useful and convenient functions for presentation or handwritten notes.
   Its key features include 6"x 8" working area for graphic design; cordless wheel mouse and rubber-coated pen and tool for lithographs, graphic arts; resolution (LPI): 2000 (default); 3 mouse buttons; Software: Adobe Photoshop Elements 3.0, Adobe Photoshop; Corel painter IX (Trial), PenSuite programme (including: Annotate All/Word, Pen Commander, PenMail, PenSigner and PenPresenter), among others.

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Intel aims for faster transistors

Indium antimonide doesn't exactly have a ring to it, but the compound could help chipmakers advance in the next decade.

Michael Kanellos

Intel plans to unfurl a prototype transistor this week that could help Moore's Law--and the semiconductor industry as a whole--continue to advance in the next decade.
   The transistor, designed by Intel and Britain's Qinetiq, is similar in structure to a traditional transistor in that it comes with a source (the place where electrons start) and a drain (their final destination) connected by a channel. A gate controls the flow of electrons across the channel; acutely controlling this flow from the source and drain determines the ones and zeros of computing.
   But, unlike in traditional transistors, the channel isn't made from silicon. Instead, it consists of indium antimonide, a compound made from the elements indium (In) and anitmony (Sb). In chemical terms, the two elements are known as III-V elements because of the row where they appear on the Periodic Table of the Elements. Silicon--Si--appears in column IV. The proximity means that indium and antimony share similar characteristics with silicon, but still behave differently.
   Intel says that replacing silicon with indium antimonide cuts power consumption by 10 times while boosting performance by 50 percent.
   Just as important, III-V materials can potentially be grafted onto established manufacturing processes. This could make transistors easier and more economical to adopt for mass manufacturing than concepts like carbon nanotube transistors and silicon nanowires.
   Chips featuring these transistors could hit the market by 2015, an Intel spokesman said. The experimental transistors right now rest on a substrate of gallium arsenide, an expensive material used in some communication chips. The company will next try to plant these III-V transistors onto a silicon substrate.
   Intel has said before that III-V materials are one of the leading ideas for keeping Moore's Law alive. The famous dictum states that the number of transistors on a chip can be doubled every two years. This doubling is largely accomplished by shrinking the size of the transistors and leads to gains in performance. Smaller transistors, however, leak electricity and dissipate heat, two major problems for computer manufacturers and chip designers. Leakage and heat have, in turn, prompted researchers to seek out new materials and transistor structures to counter these aftereffects.
   Intel and Qinetiq have shown off a similar III-V transistor before with a channel length of 200 nanometers. The transistor described in this week's paper measures 85 nanometers in length. Chips now made on the 90-nanometer process sport gates that stretch approximately 50 nanometers.
   The paper describing the transistor will be presented Wednesday at the International Electron Devices Meeting taking place in Washington, D.C.

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