Here's a seemingly simple solar power fact: the sun bathes Earth with enough energy in one hour (4.3 x 1020 joules) to more than fill all of humanity's present energy use in a year (4.1 x 1020 joules). So how to convert it? In the world of solar energy harvesting, there's a constant battle between cost and efficiency. On the one hand, complex and expensive triple-junction photovoltaic cells can turn more than 40 percent of the (specially concentrated) sunlight that falls on them into electricity. On the other, cheap, plastic solar cells under development convert less than 5 percent.In between, ubiquitous photovoltaics the multicrystalline silicon solar panels cropping up on rooftops across the country and, indeed, the world struggle to balance the need for (relatively) easy manufacturing and low cost with technology to get the most electrons for your solar buck. Yesterday, Spectrolab announced that its newest triple-junction solar cells had achieved the world record in efficiency, converting percent of specially concentrated sunlight into electricity. All told, a tiny cell just square centimeters turned the sunlight equivalent of nearly 364 suns into 4.805 watts. That kind of efficiency is why percent of satellites in orbit today bear earlier iterations of the technology; that's a total of roughlykilowatts of Spectrolab cells circling Earth.Those cells cost cents per watt, according to the manufacturer if you happen to have the sunlight equivalent of suns streaming down while enjoying a temperature of degrees Celsius. In reality, only specialized applications like satellites (and government contractors or agencies like NASA) can afford the technology. More Earth-bound photovoltaics, like Suntech's Pluto line of multicrystalline cells, which boasts percent efficiency converting one sun's light into electricity, or Suniva's ARTisun single silicon crystal cells that can convert 18.5 percent of the sunshine into electricity, cost.A solar cell (also called a photovoltaic cell) is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect. It is a form of photoelectric cell (in that its electrical characteristics e.g. current, voltage, or resistance vary when light is incident upon it) which, when exposed to light, can generate and support an electric current without being attached to any external voltage source.The tesometimes used as a photodetector (for example infrared detectors), detecting light or other electromagnetic radiation near voltage, or resistancethe range,bloger current electric or measuring light .
- The operation of a photovoltaic (PV) cell requires 3 basic attributes:
- The absorption of light, generating either electron-hole pairs or excitons.
- The separation of charge carriers of opposite types.
- The separate extraction of those carriers to an external circuit.
Theory
- The solar cell works in three steps:
- Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon.
- Electrons (negatively charged) are knocked loose from their atoms, causing an electric potential difference. Current starts flowing through the material to cancel the potential and this electricity is captured. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction.
- An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity. 1 square meter of sunlight is around 1000 watts (any person can remember this forever, even if it is not exact). Take a square meter of these panels and you have around 416 watts or about the energy to use 4 old 100 watt light bulbs (or whatever comparison you want but something people can relate to). Using numbers people can relate to will increase their understanding of the science (worked for me listening to Richard Muller's UC Berkley class called Physics for Future Presidents).Bringing the cost of just the photovoltaic cells down to about $1 per watt is the magic number solar manufacturers are aiming for, figuring that will make them cost-competitive with electricity produced by burning natural gas. Some manufacturers ofthin film cells (less efficient but cheaper), such as First Solar, claim to have reached that mark, with efficiencies .
Efficiency
"ThanksMechaMunchok...this is the real world operation problem...this is an expensive triple junction InGaAs cell...and it is showing this high efficiency under 364 suns but out there in the wild, there is only one sun, and that one is also changing its position constantly, so .the efficiency shown here has no real, practical and factual meaning....people in the solar cell business know that if theoritically modeled as a Carnot system, a single junction Si based solar cell at 6000* F has a max efficiency of 43.5%...but this can't be ever achieved... similarly this number is also not of any real use....it is really unfortunate that so much money goes into research...where as most of this money must go into deployment of the solar farms, and the improvement of the existing grid...look at what happened to the Pikin's sponsored wind farm....that would have been a good start...but just because of the primitive grid...the whole plan got scraped...big mistake and our loss....we all will regret this...as time passes on the cost of getting stuff and deploying it rises also...and soon it will overtake the benefits....then ...well won't we all say..."didn't i say so...! The efficiency of a solar cell may be broken down into reflectance efficiency, thermodynamic efficiency, charge carrier separation efficiency and conductive efficiency. The overall efficiency is the product of each of these individual efficiencies.A solar cell usually has a voltage dependent efficiency curve, temperature coefficients, and shadow angles.Due to the difficulty in measuring these parameters directly, other parameters are measured instead: thermodynamic efficiency, quantum efficiency, integrated quantum efficiency, VOCratio, and fill factor. Reflectance losses are a portion of the quantum efficiency under "external quantum efficiency". Recombination losses make up a portion of the quantum efficiency, VOC ratio, and fill factor. Resistive losses are predominantly categorized under fill factor, but also make up minor portions of the quantum efficiency, VOC ratio.The fill factor is defined as the ratio of the actual maximum obtainable power to the product of the open circuit voltage and short circuit current. This is a key parameter in evaluating the performance of solar cells. Typical commercial solar cells have a fill factor > 0.70. Grade B cells have a fill factor usually between Cells with a high fill factor have a low equivalent series resistance and a high equivalent shunt resistance, so less of the current produced by the cell is dissipated in internal losses.Single p–n junction crystalline silicon devices are now approaching the theoretical limiting power efficiency of 33.7%, noted as theShockley–Queisser limit in 1961. In the extreme, with an infinite number of layers, the corresponding limit is 86% using concentrated.New solar-cell efficiency record Bloger

It has the wingspan of a 747 and a slender fuselage, giving it the look of a giant, high-tech dragonfly.The plane's power is drawn from the sun by cells that form the top of its wings. It is collected in a series of batteries arrayed behind the craft's four electric engines.It routinely reaches altitudes of up to 8500 , well below the thin air traversed by big commercial aircraft zipping around at close to . On-board instruments alert the pilot if the plane banks even a degree too far.For all of its innovations, at this stage of development, Solar Impulse is no more practical for commercial flight than was the single-engine Spirit of St Louis that Charles Lindbergh piloted across the Atlantic Ocean in plane's engines put out about 10 horsepower - roughly the same amount as the Wright brothers' first planes. Solar Impulse cannot take off or land in windy conditions, nor can it fly through clouds. The lone pilot wears a parachute and is confined to an area the size of a ''bad economy seat,'' noted the project's chief executive and co-founder Andre , 60, an engineer and former fighter pilot.The tiny cockpit is unheated and meaning the pilot must endure extreme heat and cold and wear an oxygen mask. On long flights, meditation and advanced breathing techniques to stay. His co-founder , a psychiatrist, does self . Hypnosis.And as for bodily functions - the pilot relies on spent water bottles and eschews fibrous foods in the days before a flight to make sure that nappies do not have to be used.But comfort is not the goal. ''The point of this is to underscore how far we've come and how far we need to go to develop alternative sources of power, particularly solar energy,'' said Bob van Linden, chairman of the aeronautics department at the Smithsonian National Air and Space Museum. ''This will help push the technology along.''A plane powered only by the sun has completed the first leg of a journey that aims to cross the US.The plane, the first able to fly day and night, began a transcontinental journey that will reach Washington by mid-June.Solar Impulse lifted off from a World War II-era airfield in San Francisco on Friday and has room for only one person and an average cruising speed of about It landed in Phoenix, Arizona, some 18 hours later.
Mobile Beautiful Bloger
There were exceptions, in the chemistry and biology labs, in carpentry class.and in the gym. But by and large I grew up in a listen-and-learn culture. When I emigrated to the it was the first time I’d ever left India; in fact it was the first time I’d ever lived in a I had no choice but to listen, to understand what people were saying (their accents were strange to me), to understand what they meant (the words, idioms and usages I’d never come across). It pays to be quiet hment of children, mothers can tell if the crying comes from one of theirs or not. Amazing. Yet natural and innate. And to be expected. Similarly, a week-old baby can tell if the voice she hears is her mother’s, and is calmed. Soon after, she can distinguish her questioning. And then I started working, and came across new authority models. After a while it all became the same thing. It wasn’t about obedience or following orders or authority figures or anything didn’t speak French or German. But I listened French and German. I knew enough to be able to translate some of what was being said. Which led to some very interesting inadvertent participations in conversations in lifts and in meetings, as others assumed I couldn’t understand a word. Live and learn.I listen to test and reflect of what I’ve learnt about cooking has come about by my listening to my wife; some of it has come from listening to cooks, often face to face in their restaurants and kitchens, sometimes on TV, occasionally in a cookery class. And it was in a cookery class that I learnt to listen to food, to use the sound of the food to tell whether something is ready or not. This seems particularly true for sauces and stews, but I’ve even heard it applied in other circumstances.in such circumstances.So I walked lifts and in meetings,everywhere. It was a time when time