Dec 19 2011
Sustainable houses are the ones that are created using a process that is purely environment friendly and resource efficient. They are constructed to reduce the impact that the construction of a building puts on the environment. Sustainable houses can be of immense utility in near future as they do not harm the environment nor do they deplete earth of any of its resources. Here is the list of the best sustainable homes of 2011:
Dec 17 2011
Researchers at the Max-Born-Institute, Berlin, Germany, observed the extremely fast onset of electrical resistance in a semiconductor by following electron motions in real-time.
When you first learned about electric currents, you may have asked how the electrons in a solid material move from the negative to the positive terminal. In principle, they could move ballistically or ‘fly’ through the solid, Without being affected by the atoms or other charges of the material. But this actually never happens under normal conditions because the electrons interact with the vibrating atoms or with impurities. These collisions typically occur within an extremely short time, usually about 100 femtoseconds (10 -13 seconds, or a tenth of a trillionth of a second). So the electron motion along the material, rather than being like running down an empty street, is more like trying to walk through a very dense crowd. Typically, electrons move only with a speed of 1m per hour, they are slower than snails.
Though the electrons collide with something very frequently in the material, these collisions do take a finite time to occur. Just like if you are walking through a crowd, sometimes there are small empty spaces where you can walk a little faster for a short distance. If it were possible to follow the electrons on an extremely fast (femtosecond) time scale, then you would expect to see that when the battery is first turned on, for a very short time, the electrons really do fly unperturbed through the material before they bump into anything. This is exactly what scientists at the Max-Born-Institute in Berlin recently did in a semiconductor material and report in the current issue of the journal Physical Review Letters [volume 107, 256602 (2011)]. Extremely short bursts of terahertz light (1 terahertz = 10 12 Hz, 1 trillion oscillations per second) were used instead of the battery (light has an electric field, just like a battery) to accelerate optically generated free electrons in a piece of gallium arsenide. The accelerated electrons generate another electric field, which, if measured with femtosecond time resolution, indicates exactly what they are doing. The researchers saw that the electrons travelled unperturbed in the direction of the electric field when the battery was first turned on. About 300 femtoseconds later, their velocity slowed down due to collisions.
In the attached movie, we show a cartoon of what is happening in the gallium arsenide crystal. Electrons (blue balls) and holes (red balls) show random thermal motion before the terahertz pulse hits the sample. The electric field (green arrow) accelerates electrons and holes in opposite directions. After onset of scattering this motion is slowed down and results in a heated electron-hole gas, i.e., in faster thermal motion.
The present experiments allowed the researchers to determine which type of collision is mainly responsible for the velocity loss. Interestingly, they found that the main collision partners were not atomic vibrations but positively charged particles called holes. A hole is just a missing electron in the valence band of the semiconductor, which can itself be viewed as a positively charged particle with a mass 6 times higher than the electron. Optical excitation of the semiconductor generates both free electrons and holes which the terahertz bursts, our battery, move in opposite directions. Because the holes have such a large mass, they do not move very fast, but they do get in the way of the electrons, making them slower.
Such a direct understanding of electric friction will be useful in the future for designing more efficient and faster electronics, and perhaps for finding new tricks to reduce electrical resistance.
Dec 16 2011
The efficiency of conventional solar cells could be significantly increased, according to new research on the mechanisms of solar energy conversion led by chemist Xiaoyang Zhu at The University of Texas at Austin.
Zhu and his team have discovered that it’s possible to double the number of electrons harvested from one photon of sunlight using an organic plastic semiconductor material.
“Plastic semiconductor solar cell production has great advantages, one of which is low cost,” said Zhu, a professor of chemistry. “Combined with the vast capabilities for molecular design and synthesis, our discovery opens the door to an exciting new approach for solar energy conversion, leading to much higher efficiencies.”
Zhu and his team published their groundbreaking discovery Dec. 16 in Science.
Professor Xiaoyang Zhu
The maximum theoretical efficiency of the silicon solar cell in use today is approximately 31 percent, because much of the sun’s energy hitting the cell is too high to be turned into usable electricity. That energy, in the form of “hot electrons,” is instead lost as heat. Capturing hot electrons could potentially increase the efficiency of solar-to-electric power conversion to as high as 66 percent.
Zhu and his team previously demonstrated that those hot electrons could be captured using semiconductor nanocrystals. They published that research in Science in 2010, but Zhu says the actual implementation of a viable technology based on that research is very challenging.
“For one thing,” said Zhu, “that 66 percent efficiency can only be achieved when highly focused sunlight is used, not just the raw sunlight that typically hits a solar panel. This creates problems when considering engineering a new material or device.”
To circumvent that problem, Zhu and his team have found an alternative. They discovered that a photon produces a dark quantum “shadow state” from which two electrons can then be efficiently captured to generate more energy in the semiconductor pentacene.
Zhu said that exploiting that mechanism could increase solar cell efficiency to 44 percent without the need for focusing a solar beam, which would encourage more widespread use of solar technology.
The research team was spearheaded by Wai-lun Chan, a postdoctoral fellow in Zhu’s group, with the help of postdoctoral fellows Manuel Ligges, Askat Jailaubekov, Loren Kaake and Luis Miaja-Avila. The research was supported by the National Science Foundation and the Department of Energy.
Science Behind the Discovery:
Story Source: http://www.utexas.edu/news/2011/12/15/dark_state/
Dec 14 2011
ScienceDaily (Dec. 14, 2011) As the percentage of wind energy contributing to the power grid continues to increase, the variable nature of wind can make it difficult to keep the generation and the load balanced.
But recent work by Lawrence Livermore National Laboratory, in conjunction with AWS Truepower, may help this balance through a project that alerts control room operators of wind conditions and energy forecasts so they can make well-informed scheduling decisions. This is especially important during extreme events, such as ramps, when there is a sharp increase or decrease in the wind speed over a short period of time, which leads to a large rise or fall in the amount of power generated.
“We’re trying to forecast wind energy at any given time,” said Chandrika Kamath, the LLNL lead on the project. “One of our goals is to help the people in the control room at the utilities determine when ramp events may occur and how that will affect the power generation from a particular wind farm.”
The project, dubbed WindSENSE, is funded by the Department of Energy’s Office of Energy Efficiency and Renewable Energy.
To understand ramp events better, Kamath used data-mining techniques to determine if weather conditions in wind farm regions can be effective indicators of days when ramp events are likely to occur. She used wind energy and weather data from two regions — the Tehachapi Pass in Southern California and the Columbia Basin region on the Oregon-Washington border.
“Our work identified important weather variables associated with ramp events,” Kamath said. “This information could be used by the schedulers to reduce the number of data streams they need to monitor when they schedule wind energy on the power grid.”
With wind farms predicted to provide more energy for the grid, Kamath said it is necessary to get the wind speed predictions on target.
Wind farms in the Tehachapi Pass currently produce 700 megawatts (MW) of power, but soon will be producing 3,000 MW. In the Columbia Basin, the farms were producing 700 MW of power in 2007, but by 2009, they were producing 3,000 MW. So it is important that the wind forecasts are accurate, especially during ramp events, when the energy can change by over 1,000 MW in an hour.
“The observation targeting research conducted as part of the WindSENSE project resulted in the development and testing of algorithms to provide guidance on where to gather data to improve wind forecast performance,” said John Zack, director of forecasting of AWS Truepower. “These new software tools have the potential to help forecast providers and users make informed decisions and maximize their weather sensor deployment investment.”
The wind generation forecasts used by utilities are based on computer simulations, driven by observations assimilated into the time progression of the simulation. Observations of certain variables at certain locations have more value than others in reducing the forecast errors in the extreme events, the location of the event and the look-ahead period.
Part of the WindSENSE effort was to identify the locations and the types of sensors that can most improve short-term and extreme-event forecasts. The team used an Ensemble Sensitivity Analysis approach to identify these locations and variables.
“We’re trying to reduce the barriers to integrating wind energy on the grid by analyzing historical data and identifying the new data we should collect so we can improve the decision making by the control room operators, ” Chandrika said. “Our work is leading to a better understanding of the characteristics and the predictability of the variability associated with wind generation resources.”
Recommend this story on Facebook, Twitter,
and Google +1:
Other bookmarking and sharing tools:
Story Source:
The above story is reprinted from materials provided by DOE/Lawrence Livermore National Laboratory.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Article source: http://www.sciencedaily.com/releases/2011/12/111214125857.htm
Dec 14 2011
ScienceDaily (Dec. 13, 2011) A newly released study from the Energy Policy Institute at the University of Chicago (EPIC) concludes that small modular reactors may hold the key to the future of U.S. nuclear power generation.
“Clearly, a robust commercial SMR industry is highly advantageous to many sectors in the United States,” concluded the study, led by Robert Rosner, institute director and the William Wrather Distinguished Service Professor in Astronomy Astrophysics.
“It would be a huge stimulus for high-valued job growth, restore U.S. leadership in nuclear reactor technology and, most importantly, strengthen U.S. leadership in a post-Fukushima world, on matters of nuclear safety, nuclear security, nonproliferation, and nuclear waste management,” the report said.
The SMR report was one of two that Rosner rolled out on Dec. 1, at the Center for Strategic and International Studies in Washington, D.C. Through his work as former chief scientist and former director of Argonne National Laboratory, Rosner became involved in a variety of national policy issues, including nuclear and renewable energy technology development.
The reports assessed the economic feasibility of classical, gigawatt-scale reactors and the possible new generation of modular reactors. The latter would have a generating capacity of 600 megawatts or less, would be factory-built as modular components, and then shipped to their desired location for assembly.
The U.S. Department of Energy funded the reports through Argonne, which is operated by UChicago Argonne LLC. The principal authors of the report were Rosner and Stephen Goldberg, special assistant to Argonne’s director.
The reports followed up a 2004 UChicago study on the economic future of nuclear energy. The 2004 study concluded that the nuclear energy industry would need financial incentives from the federal government in order to build new plants that could compete with coal- and gas-fired plants.
The first report, “Analysis of GW-scale Overnight Costs,” updates the overnight cost estimates of the 2004 report. Overnight costs are the estimated costs if you were to build a new large reactor ‘overnight,’ that is, using current input prices and excluding the cost of financing.
It would now cost $4,210 per kilowatt to build a new gigawatt-scale reactor, according to the new report. This cost is approximately $2,210 per kilowatt higher than the 2004 estimate because of commodity price changes and other factors.
Struggling restart
At the Center for Strategic and International Studies event on Dec. 1, CSIS president and CEO John Hamre said that economic issues have hindered the construction of new large-scale reactors in the United States. The key challenge facing the industry is the seven-to-nine-year gap between making a commitment to build a nuclear plant and revenue generation.
Few companies can afford to wait that long to see a return on the $10 billion investment that a large-scale nuclear plant would require. “This is a real problem,” Hamre said, but the advent of the small modular reactor “offers the promise of factory construction efficiencies and a much shorter timeline.”
Natural gas would be the chief competitor of nuclear power generated by small modular reactors, but predicting the future of the energy market a decade from now is a risky proposition, Rosner said. “We’re talking about natural-gas prices not today but 10, 15 years from now when these kinds of reactors could actually hit the market.”
The economic viability of small modular reactors will depend partly on how quickly manufacturers can learn to build them efficiently. “The faster you learn, the better off you are in the long term because you get to the point where you actually start making money faster,” Rosner noted.
Small modular reactors could be especially appealing for markets that could not easily accommodate gigawatt-scale plants, such as those currently served by aging, 200- to 400-megawatt coal plants, which are likely to be phased out during the next decade, Rosner said. An unknown factor that will affect the future of these plants would be the terms of any new clean-air regulations that might be enacted in the next year.
An important safety aspect of small modular reactors is that they are designed to eliminate the need for human intervention during an emergency. In some of the designs, Rosner explained, “the entire heat load at full power can be carried passively by thermal convection. There’s no need for pumps.”
Getting the first modular reactors built will probably require the federal government to step in as the first customer. That is a policy issue, though, that awaits further consideration. “It’s a case that has to be argued out and thought carefully about,” Rosner said. “There’s a long distance between what we’re doing right now and actually implementing national policy.”
The full reports can be downloaded at the Energy Policy Institute website: http://epic.uchicago.edu/page/publications-and-presentations.
Recommend this story on Facebook, Twitter,
and Google +1:
Other bookmarking and sharing tools:
Story Source:
The above story is reprinted from materials provided by University of Chicago. The original article was written by Steve Koppes.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Article source: http://www.sciencedaily.com/releases/2011/12/111213190154.htm
Dec 13 2011
ScienceDaily (Dec. 13, 2011) Hui Hu pulled a model wind turbine from the top of an office filing cabinet.
The turbine tower was just 10 inches high. Its three blades were 10 inches in diameter. It was a perfect 1:320 scale reproduction of the 80-meter diameter wind turbines spinning across Iowa, the country’s second-ranked state in installed wind power capacity. That mini turbine is helping a research team led by Hu, an Iowa State University associate professor of aerospace engineering, understand how hills, valleys and the placement of turbines affect the productivity of onshore wind farms.
While the wind industry has data about offshore turbine performance over flat water — especially from European studies — Hu said there’s little data about the effects of uneven ground on wind turbines.
And so Hu and his research team have created the mini turbines and started running tests in Iowa State’s $1.25 million Aerodynamic/Atmospheric Boundary Layer Wind and Gust Tunnel.
“We want to work with the wind turbine industry to transfer some of our findings,” Hu said. “We can help boost total energy capture. And we can lengthen the lifetimes of wind turbines, making them more efficient.”
The research team led by Hu includes Richard Wlezien, professor and Vance and Arlene Coffman Endowed Chair in Aerospace Engineering; Partha Sarkar, a professor of aerospace engineering, of civil, construction and environmental engineering, and director of Iowa State’s Wind Simulation and Testing Laboratory; Zifeng Yang, a former Iowa State post-doctoral researcher and now an assistant professor at Wright State University in Dayton, Ohio; Wei Tian, a post-doctoral research associate in aerospace engineering; and Ahmet Ozbay, a graduate student in aerospace engineering.
The engineers’ studies are supported by a three-year, $300,000 grant from the National Science Foundation and a two-year, $100,000 grant from the Iowa Alliance for Wind Innovation and Novel Development.
The researchers are using wind tunnel tests to quantify the characteristics of surface winds over hilly terrains, determine the best placement of wind turbines on hilly terrains and find the best design for large wind farms on hilly terrains.
Experiments include:
Hu said preliminary results indicate that wind turbines on hilly terrain are hit with much higher wind loads than turbines on flat terrain. The experiments also show that, compared with turbines on flat ground, wind flowing over hilly terrain recovers its power potential more rapidly as it moves from turbine to turbine.
Data from the wind tunnel indicate a turbine on flat ground in the wake of another turbine at a distance equal to six times the diameter of the turbines loses 13 percent of power production. A turbine in the wake of another with the same downstream distance on hilly ground loses 3 percent of power production.
“That means you can put wind turbines closer together in hilly terrain,” he said.
In November, Hu, Yang and Sarkar published the first paper about their wind-turbine studies — “Visualization of the tip vortices in a wind turbine wake” on the Journal of Visualization’s website. The three researchers also presented findings of their turbine wake studies at the June 2011 Applied Aerodynamics Conference of the American Institute of Aeronautics and Astronautics.
The project’s next steps include building a nine-turbine array in Iowa State’s big wind tunnel to study power production and wind flows through a mini wind farm.
Hu is confident that data from the experiments can be valuable as more and more wind farms are built across Iowa and the country.
“These studies are telling us things we didn’t know before,” Hu said. “And this will help optimize the design of wind turbine layouts with consideration of the terrain.”
Recommend this story on Facebook, Twitter,
and Google +1:
Other bookmarking and sharing tools:
Story Source:
The above story is reprinted from materials provided by Iowa State University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Article source: http://www.sciencedaily.com/releases/2011/12/111213122631.htm
Dec 12 2011
ScienceDaily (Dec. 12, 2011) It’s time to stop thinking of solar energy as a boutique source of power, says Joshua Pearce.
Sure, solar only generates about 1 percent of the electricity in the US. But that will change in a few years, says Pearce, an associate professor of electrical engineering and materials science at Michigan Technological University. The ultimate in renewable energy is about to go mainstream.
It’s a matter of economics. A definitive new analysis by Pearce and his colleagues at Queens University in Kingston, Ontario, shows that solar photovoltaic systems are very close to achieving the tipping point in many regions: they can make electricity that’s as cheap — sometimes cheaper — than what consumers pay their utilities.
Here’s why. First, the price of solar panels has plummeted. “Since 2009, the cost has dropped 70 percent,” says Pearce. But more than that, the assumptions used in previous studies have not given solar an even break.
“Historically, when comparing the economics of solar and conventional energy, people have been very conservative,” says Pearce.
To figure out the true cost of photovoltaic energy, analysts need to consider several variables, including the cost to install and maintain the system, finance charges, how long it lasts, and how much electricity it generates. Pearce and his colleagues performed an exhaustive review of the previous studies and concluded that the values given those variables were out of whack.
“It is still a common misconception that solar PV technology has a short life and is therefore extremely expensive,” he said. However, PV panels are solid-state electronic devices with no moving parts and should last a long time. “Based on the latest long-term studies, we should be doing our economic analysis on a 30-year lifetime at minimum,” Pearce said.
In addition, most analyses assume that the productivity of solar panels will drop at an annual rate of 1 percent or more, a huge overestimation, according to Pearce. “If you buy a top-of-the-line solar panel, it’s much less, between 0.1 and 0.2 percent.”
Finally, “The price of the solar equipment has been dropping, so you’d think that the older papers would have higher cost estimates,” Pearce said. “That’s not necessarily the case.” Equipment costs are determined based on dollars per watt of electricity produced. Very recent studies set the amount between $2 and $10. The true cost in 2011, says Pearce, is under $1 per watt for solar panels on the global market, though system and installation costs vary widely. In some parts of the world, solar is already economically superior, and the study concludes that solar will become an increasingly economical source of electricity over expanding geographical regions.
In regions with a burgeoning solar industry, thanks to government programs that pay a premium for renewable energy, there are lots of solar panel installers, which heats up the market. “Elsewhere, installation costs have been high because contractors will do just one job a month,” says Pearce. “Increasing demand and competition would drop installation costs considerably.”
Furthermore, economic studies like Pearce’s don’t generally taken into account solar energy’s intangible benefits, reduced pollution and carbon emissions. And while silicon-based solar panels do rely on a nonrenewable resource — sand — they are no threat to the world’s beaches. It only takes about a sandwich baggie of sand to make a roof’s worth of thin-film photovoltaic cells, Pearce said.
Based on the study, and on the fact that the cost of conventional power continues to creep upward, Pearce believes that solar energy will soon be a major player in the energy game. “It’s just a matter of time before market economics catches up with it,” he says.
Recommend this story on Facebook, Twitter,
and Google +1:
Other bookmarking and sharing tools:
Story Source:
The above story is reprinted from materials provided by Michigan Technological University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Article source: http://www.sciencedaily.com/releases/2011/12/111212144242.htm
Dec 12 2011
ScienceDaily (Dec. 11, 2011) An energy quiz which tests people’s knowledge of the amount of energy used by various devices and processes, such as leaving the lights switched on the Christmas tree, has been developed by researchers at the University of Southampton.
A team led by Dr Alex Rogers at the University’s ECS — Electronics and Computer Science, developed The Energy Quiz, a “game with a purpose” for BT to challenge its employees to test their knowledge about energy and ECS and will launch a new version on 12 December.
The online quiz, which can be found at: http://www.energy-quiz.org invites players to compete and to answer 12 questions about energy comparisons. For example, it asks: which uses more energy a Christmas tree with 100 lights continuously lit over the festive period or a dishwasher used once a week for month; or it compares heating water for a typical office for a year with a full Boeing 747 flying 400 miles with heating a typical office for a day versus driving a car 100 miles. BT has invited 200 employees to play the game and will roll it out to a further 3,500 in the next phase.
“For us this is a way of conserving energy and we are finding that there is a deficiency of knowledge about energy among our employees,” said Simon Thompson, BT Chief Researcher. “We have also found that this kind of knowledge is often dull for people and they are not too interested in the statistics, so if we can encourage them to play a game around energy, it makes it more fun.” According to Dr Rogers, The Energy Quiz can be tailored to specific work or home environments. With the release of an updated version worldwide this week, he plans to analyse the data to explore people’s misconceptions about energy. “Our informal results so far show that people have a lot less intuition about energy than you would think,” he said. “People think that home consumption is always higher than driving their car to work and they often assume that appliances in the foreground that make a lot of noise or generate heat use more energy over the course of a year than something hidden away in the background.”
The Energy Quiz is one of a whole host of tools to monitor energy being developed at ECS. Dr Rogers and his team have also developed a range of tools to visualise the real-time carbon intensity of the UK electricity grid and they have developed tools for building energy monitoring.They are also developing computerised agents that can negotiate the charging of electric-powered cars in the most efficient way.
Recommend this story on Facebook, Twitter,
and Google +1:
Other bookmarking and sharing tools:
Story Source:
The above story is reprinted from materials provided by University of Southampton, via AlphaGalileo.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Article source: http://www.sciencedaily.com/releases/2011/12/111211221944.htm
Dec 12 2011
ScienceDaily (Dec. 9, 2011) An innovative project led by a chemistry academic at the University of Southampton is using solar generators to provide IT resources and ‘hands-on’ science for students in developing countries.
A major difficulty in teaching science subjects in developing countries, especially in rural schools, is that students are rarely able to get ‘hands-on’ experience of experiments. This could be partly due to a lack of equipment, chemicals and facilities but mainly because of a lack of electricity and running water.
Now, Professor Tony Rest, a visiting Chemistry academic at the University of Southampton, and Keith Wilkinson, formerly a teacher at the International School at Lusaka in Zambia, have devised a solar-powered solution based on a digital projector and low-cost solar energy panels so that students can gain access to IT and other modern teaching methods.
Professor Rest says: “The lack of electricity is a particularly serious matter for rural schools and this situation is unlikely to get better in the near to medium future. With drawbacks to petrol generators, due to difficulties in getting supplies and safety hazards, solar energy generators have become available at cost-effective prices and provide a sustainable answer as rural schools have an abundance of the basic energy source required to power them — sunshine.
Most data/video projectors require 200-300 watt and cannot be economically sustained by solar power in rural villages. However, the advent of mini-projectors, which require about 50 watts of power, has revolutionised the situation and made battery powered projection feasible.
The solar energy generators, which consist of solar panels, batteries and inverters, can be linked to the projector for students to get practical classes via multimedia resources to show laboratory experiments and stress practical techniques.
Professor Rest adds: “These experiences can be extended to other science subjects from physics, biology and maths, to subjects involving practical elements, such as engineering, and to craft subjects, including plumbing, carpentry, and catering, where students need see how to acquire skills. By extending the breadth of subjects benefiting from the use of IT, the overall cost of using a solar energy generator is reduced. Another spin-off is that students in rural schools gain access to valuable IT skills.”
The project has been developed by the ‘Chemistry Aid’ project, the Chemistry Video Consortium based at the University of Southampton, with support from the Royal Society of Chemistry, which has provided multimedia teaching resources.
Recommend this story on Facebook, Twitter,
and Google +1:
Other bookmarking and sharing tools:
Story Source:
The above story is reprinted from materials provided by University of Southampton.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Article source: http://www.sciencedaily.com/releases/2011/12/111209123108.htm
Dec 11 2011
ScienceDaily (Dec. 1, 2011) Imec together with its silicon photovoltaic industrial affiliation program partners Schott Solar, Total, Photovoltech, GDF-SUEZ, Solland Solar, Kaneka and Dow Corning, have demonstrated an excellent conversion efficiency of 23.3% on interdigitated back-contact (IBC) silicon solar cells.
Interdigitated back contacts are introduced to increase the conversion efficiency of crystalline silicon solar cells and allow for further reduction of the cell thickness, simplification of module fabrication and improved aesthetics of the final solar cell modules. Imec has developed a high-efficiency baseline process for small-area IBC cells within its multi-partner silicon solar cells industrial affiliation program that aims at increasing the efficiency well above 20% and decreasing the cost of silicon solar cells beyond the current state-of-the-art.
Key aspects of the newly developed small-area (2×2 cm2) IBC Si solar cells are the n-type base float-zone (FZ) silicon substrates, a random pyramid texture, a boron diffused emitter, phosphorus diffused front- and back surface fields, a thermally grown silicon dioxide for surface passivation, a SiN single layer anti-reflective coating, lithography based patterning and Aluminum metallization. The realized IBC cells achieve a designated area conversion efficiency of 23.3% (Jsc = 41.6 mA, Voc=696 mV, FF=80.4%), certified by ISE-Callabs.
“As silicon photovoltaic industrial affiliation program partners of imec we are very happy with this new result,” says Dr. Martin Heming, CEO of SCHOTT Solar. This German solar manufacturer was the first industry partner to join imec’s program on silicon solar cells. “The test result confirms our confidence in imec’s excellent PV RD capabilities and vision, and it allows us to acquire important know-how and IP as basis for our next generation solar cell products.”
Recommend this story on Facebook, Twitter,
and Google +1:
Other bookmarking and sharing tools:
Story Source:
The above story is reprinted from materials provided by Interuniversity Microelectronics Centre (IMEC).
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Article source: http://www.sciencedaily.com/releases/2011/12/111201094257.htm
