New solar-cell efficiency record set Bloger

  New solar-cell efficiency Bloger

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.

In contrast, a solar thermal collector collects heat by absorbing sunlight, for the purpose of either direct heating or indirect electrical power generation. "Photoelectrolytic cell" (photoelectrochemical cell), on the other hand, refers either a type of photovoltaic cell (like that developed by A.E. Becquerel and modern dye-sensitized solar cells) or a device that splits water directly into hydrogen and oxygen using only solar illumination. more than $2 per watt. Installation roughly doubles that price. Is that a simple solar power fact? I don't know of anyone who could easily fathom the amount of sun that shines on the entire earth for  hour.
             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

Bloger Research Corporation.

Overview: Our basic research goal is to observe and study the internal structure and composition of white dwarf stars, the remnants of a nuclear fusion furnace that once turned hydrogen into helium and energy, a process which still powers stars like the Sun. An unexpected circumstance allows us to probe their structure: some of these stars vibrate in a periodic manner that sends seismic waves deep through their interior and brings information to the surface. We see this manifested as complex periodic variations in their brightness, which we can study and analyze, much as seismologists study the inner structure of the earth using earthquakes. White dwarfs once supported steady nuclear fusion, and would again if hydrogen were injected into them. We essentially have a working fusion laboratory to study, one that we must understand in detail if we are ever to master this clean sustainable energy source and duplicate the process on this planet.Whole Earth TelescopeWe can determine the internal structure of pulsating white dwarfs using the techniques of high speed photometry to observe their variations in brightness over time, and then matching these observations with a computer model which behaves the same way. The parameters of the model are chosen to correspond one-to-one with the physical processes that give rise to the variations, so a good fit to the data gives us confidence that our model reflects the actual physics of the stars themselves. In the past decade, the observational requirements of white dwarf seismology have been satisfied by the development of the Whole Earth Telescope an informal collaboration of astronomers at observatories around the globe who cooperate to produce nearly continuous time-series photometry of white dwarfs for up to 14 days at a time. This instrument has provided a wealth of seismological data on the different varieties of pulsating white dwarf stars.In an effort to bring the analysis of WET data to the level of sophistication demanded by the observations, we are developing a model-fitting method based on a genetic algorithm. The underlying ideas for genetic algorithms were inspired by Charles Darwin's notion of biological evolution through natural selection. The basic idea is to solve a problem by evolving the best solution from an initial set of random guesses. The computer model provides the framework within which the evolution takes place, and the individual parameters controlling it serve as the genetic building blocks. Observations provide the selection pressure. In practice, this method is much more efficient than other comparably global techniques.                             

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Time-series CCD photometer:The study of pulsating white dwarfs requires a special kind of instrument capable of high speed imaging. When studying phenomena that change rapidly, we do not have the luxury of increasing our exposure time to improve the signal. Our instrument must be highly efficient even with short exposures. We also need high timing precision to determine the beginning and duration of each exposure accurately. Most CCD cameras cannot obtain data continuously -- there is a dead time between exposures when the detector is busy reading out the previous image. The time required varies from a few seconds to a few minutes. We need an instrument with essentially zero dead time, so we can record the rapidly variable phenomena without interruption.We are a tax-exempt non-profit organization dedicated to scientific research and public education. We support and conduct scientific research on topics relevant to the observational and theoretical properties of stars, and we create and distribute public education resources through our website. If you would like to support one of the projects below by donating equipment, time, or funding, please find out how you can help or consider making a secure online donation. If you have any questions, or other ideas for how you might be able to gete public education of stars, involved with one of these projects. Bloger Research Corporation.

Engineer Looks to Dragonflies, for Flight Lessons Bloger

  Engineer Lessons Bloger.

There has always been a need to efficiently carry more people and more cargo. And so the science and engineering of getting large aircraft off the ground is very well understood.But what about flight at a small scale? Say the scale of a dragonfly, a bird or a bat?Hui an Iowa State University associate professor of aerospace engineering, said there hasn't been a need to understand the airflow, the eddies and the spinning vertices created by flapping wings and so there haven't been many engineering studies of small-scale flight. But that's changing.The U.S. Air Force, for example, is interested in insect-sized nano-air vehicles or bird-sized micro-air vehicles. The vehicles could fly microphones, cameras, sensors, transmitters and even tiny weapons right through a terrorist's doorway.So how do you design a little flier that's fast and agile as a house fly?says a good place to start is nature itself.And so for a few years he's been using wind tunnel tests and imaging technologies to learn why dragonflies and bats are such effective fliers. How, for example, do flapping frequency, flight speed and wing angle affect the lift and thrust of a flapping wing? studies of bio-inspired aerodynamic designs began in 2008 when he spent the summer on a faculty fellowship at the Air Force Research Laboratory at Air Force Base in Florida. Over the years he's published papers describing aerodynamic performance of different kinds of flapping wings.A study based on the dragonfly, for example, found the uneven, surface of the insect's wing performed better than a smooth airfoil in the slow-speed, high-drag conditions of small-scale flight. Using particle image - an imaging technique that uses lasers and cameras to measure and record flows found the corrugated wing created tiny air cushions that kept oncoming airflow attached to the wing's surface. That stable airflow helped boost performance in the challenging flight conditions. By describing the underlying physics of dragonfly flight, and Jeffery Murphy, a former Iowa State graduate student, won a 2013 Best Paper Award in applied aerodynamics from the American Institute of Aeronautics and Astronautics.Another study of bat-like wings found the built-in flexibility of membrane-covered wings helped decrease drag and improve flight performance.And what about building tiny -covered and power flying machines that use flapping wings? Can engineers come up with a reliable way to make that work?He has been looking into that, too.He's using piezoelectric, materials that bend when subject to an electric current, to create flapping movements. That way flapping depends on feeding current to a material, rather than relying on a motor, gears and other moving parts.There used his wind tunnel and imaging tests to study how pairs of flapping wings work together -- just like they do on a dragonfly. He learned wings flapping out of sync (one wing up while the second is down) created more thrust. And tandem wings working side by side, rather than top to bottom, maximize thrust and lift.He said these kinds of physics and aerodynamics lessons -- and many more -- need to be learned before engineers can design effective nano-studies of bio-inspired aerodynamic designs began in 2008 when he spent the summer on a faculty fellowship at the Air Force Research Laboratory at Air Force Base in Florida. Over the years he's published papers describing aerodynamic performance of different kinds of flapping wings and micro-scale vehicles.And so he's getting students immersed in the studies. who has won a , three-year National Science Foundation grant that sends up to 12 Iowa State students to China's Shanghai Tong University for eight weeks of intensive summer research. The students work at the university's J.C. Wu Aerodynamics Research Center to study bio-inspired aerodynamics and engineering problems."We're just now learning what makes a dragonfly work," said. "There was no need to understand  Shanghai Tong University flight at these small scales.