Advantages of Solar Power
Solar power is a renewable source generated from the sun, meaning that the solar energy source is never going to finish. So, we do not need to worry about we may jeopardy of the energy source if you over use it.

Solar power is environmental friendly energy source. Unlike oil, the use of solar energy will never causes green house effects or emits carcinogens into the air and causes the air pollution.

The sun is FREE. Unlike the traditional energy source which you need to pay more if you use more, there is not limit on how much you can use the energy generated from solar power, and you do not need to think of the electricity cost when you use a solar-powered energy generator, because the sun is FOC (Free of Charge).

Little maintenance cost on solar power system. Solar cells can last for a lifetime and because there are no moving parts, it needs very little maintenance. You do not really need to allocate significant budget for it maintenance cost.

Disadvantages of Solar Power
The key stopping factor that makes most of people who are interested to install solar power system is the total cost is expensive. A solar power system that provides enough energy to power an average sized home can cost anywhere from $6,000 to $20,000. Seeing the potential market demand on solar power system, the industries with continue research efforts are trying to reduce the material costs. Moreover, there are many simple-to-follow DIY instruction manuals had been made published to teach people how to build their own solar power system using cheap materials which can be found at local market.

The solar power can be generated without sunlight, which means the power cannot be created at night, during rain and winter season when sun is hiding behind the cloud. This had been one of key discouragement of using solar power as the alternative power solution.

If you build the solar panel at the roof of your home, it becomes part of the house. You may need to sell it together with your house if you decide to move to a new home. And you need to reinstall the solar power system at your new home.

Summary
You should clearly understand of both the advantages and the disadvantages of solar power system before you go ahead to convert your home to be solar-powered so that you can really benefited from the advantages of solar power while handling the disadvantages of solar power to minimize the impacts.

Transparent solar cells offer a multitude of uses. (Credit: Image courtesy of Fraunhofer-Gesellschaft)

To translate the vision of see-through solar cells and transparent electronics into reality, two different transparent coatings would be required – one to conduct the electricity via electrons, the n-conductors, and one in which electron holes enable the electricity to flow, the p-conductors. To produce these coatings the engineers dope the base material with a few other atoms. Depending on which atoms they use, they obtain the differently conducting coatings. N-conducting transparent materials are state of the art, but the p-conductors are problematic. Their conductivity is too low and often their transparency is poor. Manufacturers need a transparent base material which is amenable to both n- and p-doping.

At present, indium tin oxide is mainly used for the n-conductors, but this is costly. Indium has become a rare commodity and its price has increased tenfold since 2002. The search for substitute materials is therefore in full swing. At the same time, various questions need to be answered, such as which materials would be best suitable, what they should be doped with to obtain good conductivity, and how good their transparency is. Research scientists at the Fraunhofer Institute for Mechanics of Materials IWM working in cooperation with other Fraunhofer colleagues have developed material physics models and methods which help in the search.

“If transparent p-conductors with adequate conductivity could be produced, it would be possible to realize completely transparent electronics,” says Dr. Wolfgang Körner, research scientist at the IWM. Using electron microscope images, the researchers initially determine the grain boundaries which most frequently occur in the material – i.e. irregularities in the ordered crystal structure. These defect structures are modeled atom by atom. Special simulation methods calculate how the electrons are distributed in the structures and thus in the solid body. From the data the researchers extract how conductive and transparent the material is. “We have found, for example, that phosphorus is suitable for p-doping zinc oxide, but that nitrogen is more promising,” says Körner.

Fraunhofer-Gesellschaft. “Transparent Solar Cells Made For Windows.” ScienceDaily

Now, a team of University of Florida chemists is the latest to report a new mechanism to transform light straight into motion – albeit at a very, very, very tiny scale.

In a paper expected to appear soon in the online edition of the journal Nano Letters, the UF team reports building a new type of “molecular nanomotor” driven only by photons, or particles of light. While it is not the first photon-driven nanomotor, the almost infinitesimal device is the first built entirely with a single molecule of DNA — giving it a simplicity that increases its potential for development, manufacture and real-world applications in areas ranging from medicine to manufacturing, the scientists say.

“It is easy to assemble, has fewer parts and theoretically should be more efficient,” said Huaizhi Kang, a doctoral student in chemistry at UF and the first author of the paper.

The scale of the nanomotor is almost vanishingly small.

In its clasped, or closed, form, the nanomotor measures 2 to 5 nanometers — 2 to 5 billionths of a meter. In its unclasped form, it extends as long as 10 to 12 nanometers. Although the scientists say their calculations show it uses considerably more of the energy in light than traditional solar cells, the amount of force it exerts is proportional to its small size.

But that won’t necessarily limit its potential.

In coming years, the nanomotor could become a component of microscopic devices that repair individual cells or fight viruses or bacteria. Although in the conceptual stage, those devices, like much larger ones, will require a power source to function. Because it is made of DNA, the nanomotor is biocompatible. Unlike traditional energy systems, the nanomotor also produces no waste when it converts light energy into motion.

“Preparation of DNA molecules is relatively easy and reproducible, and the material is very safe,” said Yan Chen, a UF chemistry doctoral student and one of the authors of the paper.

Applications in the larger world are more distant. Powering a vehicle, running an assembly line or otherwise replacing traditional electricity or fossil fuels would require untold trillions of nanomotors, all working together in tandem — a difficult challenge by any measure.

“The major difficulty lies ahead,” said Weihong Tan, a UF professor of chemistry and physiology, author of the paper and the leader of the research group reporting the findings. “That is how to collect the molecular level force into a coherent accumulated force that can do real work when the motor absorbs sunlight.”

Tan added that the group has already begun working on the problem.

“Some prototype DNA nanostructures incorporating single photo-switchable motors are in the making which will synchronize molecular motions to accumulate forces,” he said.

To make the nanomotor, the researchers combined a DNA molecule they created in the lab with azobenzene, a chemical compound that responds to light. A high-energy photon prompts one response; lower energy another.

To demonstrate the movement, the researchers attached a fluorophore, or light-emitter, to one end of the nanomotor and a quencher, which can quench the emitting light, to the other end. Their instruments recorded emitted light intensity that corresponded to the motor movement.

“Radiation does cause things to move from the spinning of radiometer wheels to the turning of sunflowers and other plants toward the sun,” said Richard Zare, distinguished professor and chairman of chemistry at Stanford University. “What Professor Tan and co-workers have done is to create a clever light-actuated nanomotor involving a single DNA molecule. I believe it is the first of its type.”

The National Institutes of Health and the National Science Foundation funded the research. The other coauthors of this paper are Haipeng Liu, Joseph A. Phillips, Zehui Cao, Youngmi Kim, Zunyi Yang and Jianwei Li.

University of Florida. “New, Light-driven Nanomotor Is Simpler, More Promising, Scientists Say” ScienceDaily

Cell phones, computers, MP3 players, kitchen stoves, and irons all have one thing in common: They need electricity. And in the future, more and more cars will also be fuelled by electric power. If the latest forecast from the World Energy Council WEC can be believed, global electricity requirements will double in the next 40 years. At the same time, prices for the dwindling resources of petroleum and natural gas are climbing.

“Rising energy prices are making alternative energy sources increasingly cost-effective. Sometime in the coming years, renewable energy sources, such as solar energy, will be competitive, even without subsidization,” explains Dr. Arnold Gillner, head of the microtechnology department at the Fraunhofer Institute for Laser Technology in Aachen, Germany. “Experts predict that grid parity will be achieved in a few years. This means that the costs and opportunities in the grid will be equal for solar electricity and conventionally generated household electricity.” Together with his team at the Fraunhofer Institute for Laser Technology ILT in Aachen, this researcher is developing technologies now that will allow faster, better, and cheaper production of solar cells in the future. “Lasers work quickly, precisely, and without contact. In other words, they are an ideal tool for manufacturing fragile solar cells. In fact, lasers are already being used in production today, but there is still considerable room for process optimization.” In addition to gradually improving the manufacturing technology, the physicists and engineers in Aachen are working with solar cell developers – for example, at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg – on new engineering and design alternatives.

New production technologies allow new design alternatives
At “Laser 2009” in Munich, the researchers will be demonstrating how lasers can drill holes into silicon cells at breathtaking speed: The ILT laser system drills more than 3,000 holes within one second. Because it is not possible to move the laser source at this speed, the experts have developed optimized manufacturing systems which guide and focuses the light beam at the required points. “We are currently experimenting with various laser sources and optical systems,” Gillner explains. “Our goal is to increase the performance to 10,000 holes a second. This is the speed that must be reached in order to drill 10,000 to 20,000 holes into a wafer within the cycle time of the production machines.”

The tiny holes in the wafer – their diameter is only 50 micrometers – open up undreamt-of possibilities for the solar cell developers. “Previously, the electrical contacts were arranged on the top of the cells. The holes make it possible to move the contacts to the back, with the advantage that the electrodes, which currently act as a dark grid to absorb light, disappear. And so the energy yield increases. The goal is a degree of efficiency of 20 percent% in industrially-produced emitter wrap-through (EWT) cells, with a yield of one-third more than classic silicon cells,” Gillner explains. The design principle itself remains unchanged: In the semi-conductor layer, light particles, or photons, produce negative electrons and positive holes, each of which then wanders to the oppositely poled electrodes. The contacts for anodes and cathodes in the EWT cells are all on the back, there is no shading caused by the electrodes, and the degree of efficiency increases. With this technique, it may one day be possible to use unpurified “dirty” silicon to manufacture solar cells that have poorer electrical properties, but that are cheaper.

Drilling holes into silicon cells is only one of many laser applications in solar cell manufacturing. In the EU project Solasys – Next Generation Solar Cell and Module Laser Processing Systems – an international research team is currently developing new technologies that will allow production to be optimized in the future. ILT in Aachen is coordinating the six million euro project. “We are working on new methods that make the doping of semiconductors, the drilling and the surface structuring of silicon, the edge isolation of the cells, and the soldering of the modules more economical,” project coordinator Gillner explains. For example, “selective laser soldering” makes it possible to improve the rejection rates and quality of the contacting, and so reduce manufacturing costs. Until now, the electrodes were mechanically pressed onto the cells, and then heated in an oven. “But silicon cells often break during this process,” Gillner knows. “Breakage is a primary cost factor in production.” On the other hand, however, with “selective laser soldering” the contacts are pressed on to the cells with compressed air and then soldered with the laser. The mechanical stress approaches zero and the temperature can be precisely regulated. The result: Optimal contacts and almost no rejects.

Laser technology means more efficient thin film cells
Laser technology is also helping to optimize the manufacture of thin film solar cells. The extremely thin film packages made of semiconducting oxide, amorphous silicon, and metal that are deposited onto the glass panels still have a market share of only ten percent. But as Gillner knows, “This could be higher, because thin film solar cells can be used anywhere that non-transparent glass panels can be mounted, for example, on house facades or sound-insulating walls. But the degrees of efficiency are comparable low at five to eight percent, and the production costs are comparatively high.” The laser researchers are working to improve these costs. Until now, the manufacturers have used mechanical methods or solid-state lasers in the nanosecond range in order to structure the active layers on the glass panels. In order to produce electric connections between the semiconductor and the metal, grooves only a few micrometers wide must be created. At the Fraunhofer-Gesellschaft booth at “Laser 2009” the ILT researchers will be demonstrating a 400-watt ultrashort pulse laser that processes thin-film solar modules ten times faster than conventional diode-pumped solid-state lasers. “The ultrashort pulse laser is an ideal tool for ablating thin layers: It works very precisely, does not heat the material and, working with a pulse frequency of 80 MHz, can process a 2-by-3 meter glass panel in under two minutes,” Gillner reports. “The technology is still very new, and high-performance scanning systems and optical systems adapted to the process must be developed first. In the medium term, however, this technology will be able to reduce production costs.”

The rise of laser technology in solar technology is just taking off, and it still has a long way to go. “Lasers simplify and optimize the manufacture of classic silicon and thin-film cells, and they allow the development of new design alternatives,” Gillner continues. “And so laser technology is making an important contribution towards allowing renewable energy sources to penetrate further into the energy market.”

Fraunhofer-Gesellschaft. “Lasers Are Making Solar Cells Competitive” ScienceDaily

This system has been developed by Daniel Chemisana, member of the research group in Agrometeorology and Energy for Environment, leaded by UdL lecturers Manel Ibáñez and Joan Ignasi Rosell.

This thermal-photovoltaic modular system has a solar concentration of 10 suns, that is, it only needs a tenth part of a standard system’s active surface to produce the same energy, be it electricity, heat, or both simultaneously. Besides the reduction in the surface of used solar cells and the cost reduction this implies, this new technology can generate cold by connecting a heat pump to the system.

Rosell highlighted the architectural integration that these modules will allow either in roofs or in façades, which will reduce their visual impact. They can be directly installed in roofs, on the closure of concrete or brick blocks, forming a curtain wall in the façades or as a part of the railings in terraces, “as if they were a building’s second skin”. They can also be used in residential buildings, companies or farms.

The system, of which the international patent has already been requested, consists of a stationary lens and a linear absorber plate that concentrates sunlight to generate energy. This concentration system reduces the space that until now was needed with traditional plates, which move around in search of sunlight.

Rosell also underlined the global efficiency of energetic conversion in this module, which could rise above 60%. Researchers at UdL anticipate that the product could be commercialised in a year if companies opt for this technology. The prototype has financed by CIDEM and has the support of the UdL Technological Springboard.

ScienceDaily
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Scanning electron microscope image of typical titania nanotubes for a photocatalytic cell to produce hydrogen gas from water

A research team from Northeastern University and the National Institute of Standards and Technology (NIST) has discovered, serendipitously, that a residue of a process used to build arrays of titania nanotubes-a residue that wasn’t even noticed before this-plays an important role in improving the performance of the nanotubes in solar cells that produce hydrogen gas from water. Their recently published results* indicate that by controlling the deposition of potassium on the surface of the nanotubes, engineers can achieve significant energy savings in a promising new alternate energy system.

Titania (or titanium dioxide) is a versatile chemical compound best known as a white pigment. It’s found in everything from paint to toothpastes and sunscreen lotions. Thirty-five years ago Akira Fujishima startled the electrochemical world by demonstrating that it also functioned as a photocatalyst, producing hydrogen gas from water, electricity and sunlight. In recent years, researchers have been exploring different ways to optimize the process and create a commercially viable technology that, essentially, transforms cheap sunlight into hydrogen, a pollution-free fuel that can be stored and shipped.

Increasing the available surface area is one way to boost a catalyst’s performance, so a team at Northeastern has been studying techniques to build tightly packed arrays of titania nanotubes, which have a very high surface to volume ratio. They also were interested in how best to incorporate carbon into the nanotubes, because carbon helps titania absorb light in the visible spectrum. (Pure titania absorbs in the ultraviolet region, and much of the ultraviolet is filtered by the atmosphere.)

This brought them to the NIST X-ray spectroscopy beamline at the National Synchrotron Light Source (NSLS)**. The NIST facility uses X-rays that can be precisely tuned to measure chemical bonds of specific elements, and is at least 10 times more sensitive than commonly available laboratory instruments, allowing researchers to detect elements at extremely low concentrations. While making measurements of the carbon atoms, the team noticed spectroscopic data indicating that the titania nanotubes had small amounts of potassium ions strongly bound to the surface, evidently left by the fabrication process, which used potassium salts. This was the first time the potassium has ever been observed on titania nanotubes; previous measurements were not sensitive enough to detect it.

The result was mildly interesting, but became much more so when the research team compared the performance of the potassium-bearing nanotubes to similar arrays deliberately prepared without potassium. The former required only about one-third the electrical energy to produce the same amount of hydrogen as an equivalent array of potassium-free nanotubes. “The result was so exciting,” recalls Northeastern physicist Latika Menon, “that we got sidetracked from the carbon research.” Because it has such a strong effect at nearly undetectable concentrations, Menon says, potassium probably has played an unrecognized role in many experimental water-splitting cells that use titania nanotubes, because potassium hydroxide is commonly used in the cells. By controlling it, she says, hydrogen solar cell designers could use it to optimize performance.

* C. Richter, C. Jaye, E. Panaitescu, D.A. Fischer, L.H. Lewis, R.J. Willey and L. Menon. Effect of potassium adsorption on the photochemical properties of titania nanotube arrays. J. Mater. Chem., published online as an Advanced Article, March 27, 2009. DOI: 10.1039/b822501j

** The NSLS is part of the Department of Energy’s Brookhaven National Laboratory.

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Australian Scientists developing spray on solar panels

Solar cells are usually made of silicon coated with a thin layer of silicon nitrate. This silicon nitrate works as an anti-reflective agent to boost cell efficiency. But the catch is these types of cells are costly to produce. This anti-reflective layer deposition happens in vacuum and creating vacuum like situation doesn’t come cheap!

Efforts are on to reduce the cost of solar cells. Australia too is abundant in natural resources and wants to trap these for clean and green energy. Researchers in Australia are handling a three year project which will develop a spray-on coating for solar panels. They will concentrate on cost reduction and efficiency of solar panels too. A new Australian solar company Spark Solar and Finnish materials company Braggone Oy are working with Australian National University (ANU) on the spray-on method. This new technique can be commercially available by 2011. Dr Keith McIntosh from ANU, the chief investigator in the first project, stated, “It will provide an opportunity for significant manufacturing cost reductions by replacing the conventional, expensive manufacturing techniques that are currently employed industry-wide with the spray-on films.”

Creating vacuums for coating of solar cells are costly. If this step can be skipped from the solar cell production, price tags can be brought down considerably. The new method uses a spray-on hydrogen film and spray-on anti-reflective film. In this spray-on method vacuums are not needed. The cells travel along a conveyor belt where the films are sprayed on. The simplified process could trim down about $5 million in capital equipment costs per medium-sized factory. The manufacturer can save and produce solar cells at a much cheaper rate. Testing of the process is now taking place at the ANU, and the technology should be available toward the end of 2011.

Improved efficiency
The second aspect of the project is efficiency of the solar cells. This project will be undertaken in collaboration with the German solar company GP Solar and led by chief investigator Dr Klaus Weber from ANU.

“We aim to develop a range of industry-ready cell fabrication sequences that will offer significantly improved conversion efficiencies” Dr Weber said. Currently solar cells are operating at the range of 5% to 24% efficiency. Solar surface of a cell has been roughened to increase the surface area. More surface area means more absorption of solar light. But a rough surface also disrupts the cell’s crystalline structure in the process. So the second project is concentrating on improving the efficiency of solar cells. They will try to change the surface of the solar cells to improve its efficiency. Once a most advantageous surface is created, the effectiveness and power of solar cells would be superior.

19 Million Cells a year
A new Australian company Spark Solar will establish a $70 million high-tech solar cell factory in the Australian Capital Territory (ACT). Their main objective will be to initiate solar cell production in 2010. The factory will take a daunting task of producing 19 million solar cells a year. That volume of production will be enough to power 20,000 homes, along with exports worth more than $400 million to Europe’s booming solar markets.

The astonishing fact is that presently the global market for solar cells is growing at a faster rate than markets for mobile phones, digital cameras and laptops!
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Advances in Solar Cell Technology

Scientists are continuously improving the existing solar cells. Now they are taking the help of computer simulations and real lab testing. A group of physicists and engineers at MIT have discovered new methods to make the existing solar cells more efficient by 50%. Currently the most efficient solar cell gives 45% output and is extremely expensive to produce. Cells produced by using this new technology will be more efficient and cost effective. Their cost effectiveness emerges from just 1% use of refined silicon. It should be noted that refined silicon is quite costly.

Cost Benefits:
Scientists want to bring clean and green energy on par with energy produced by fossil fuels. One of the biggest hurdles they face is cost. Most of the green energy is quite expensive and they have a longer break-even time. So here the MIT team has reduced the amount of extremely thin layer of silicon used in the solar cell. They are using hundreds of times less material.

Choosing Different but Simple Path:
The MIT team has paid close attention to the limiting factors of the solar cells. One of the greatest disadvantages in the existing solar cells is that whatever amount of light is falling on the solar cell has got very little time to be converted into energy. So this MIT team has concentrated its efforts on making the sunlight stay inside the cell for a longer duration of time therefore these cell can produce more energy. Peter Bermel, a postdoctoral researcher in MIT’s physics department and his team took the help of computer simulations and applied various advanced chip-manufacturing techniques.

They went for the anti-reflection coating to the front of the cell and a multi-layered reflective coating to the back of the silicon films which were ultra thin. In the end, the team settled for the best result in a multi-layered reflective coating coupled to a tightly spaced array of lines. This technique armed the cells like a laser around the cell, where light can bounce back and forth before finally exiting. This way the light stays longer inside the cell and can produce more energy. Current solar cells don’t have these coatings so the light is just reflected back to the surrounding air in the atmosphere.

“It’s critical to ensure that any light that enters the layer travels through a long path in the silicon,” Bermel said. “The issue is how far does light have to travel [in the silicon] before there’s a high probability of being absorbed” and knocking loose electrons to produce an electric current.

Trying out various combinations by computer simulations
When you have to try out various combinations and don’t know which combination will yield that magical results, its best to try out computer simulations. They will give out the excellent and almost correct results and save the time and material costs. The MIT team ran thousands of simulations with each one designed to try a slightly different approach toward keeping photons within the cell for longer. Using computer simulations they will be able to find the magical combination of multi-layered reflective coating coupled to a tightly spaced array of lines. This approach enhances the energy output of the cells by as much as 50%.

Examining the Correct combination in Laboratory
When this research team thought that they have found the right combination in the computer simulation they verified the results in the laboratory. These tests were carried out by the graduate student Lirong Zeng, in the Department of Materials Science and Engineering. According to Lionel Kimerling, who directed the project, “The experiments confirmed the predictions, and the results have drawn considerable industry interest.”

This project has caught the attention of like-minded people. Stephen Saylor, CEO of SiOnyx in Beverly, MA says, “This work demonstrates the importance of improving the performance of thin-film technologies. “SiOnyx is engaged in increasing the absorption of red and infrared light in thin silicon devices.

Bermel says that his team is already thinking of other production methods. One sound option is nanoimprint lithography, but they haven’t tried it yet. “A 35 percent efficiency increase is clearly predicted in simulations,” he opines, “but the challenge is, ‘Can you make it practically?’ That’s what we’re working on.”
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