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Solar Decathalon 2013

November 29, 2011 at 8:00 am | Solar Blog | No comment

 

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‘Fool’s gold’ aids discovery of new options for cheap, benign solar energy

November 28, 2011 at 7:56 pm | Solar Blog | No comment

 

ScienceDaily (Nov. 28, 2011) — Pyrite, better known as “fool’s gold,” was familiar to the ancient Romans and has fooled prospectors for centuries — but has now helped researchers at Oregon State University discover related compounds that offer new, cheap and promising options for solar energy.

These new compounds, unlike some solar cell materials made from rare, expensive or toxic elements, would be benign and could be processed from some of the most abundant elements on Earth. Findings on them have been published in Advanced Energy Materials, a professional journal.

Iron pyrite itself has little value as a future solar energy compound, the scientists say, just as the brassy, yellow-toned mineral holds no value compared to the precious metal it resembles. But for more than 25 years it was known to have some desirable qualities that made it of interest for solar energy, and that spurred the recent research.

The results have been anything but foolish.

“We’ve known for a long time that pyrite was interesting for its solar properties, but that it didn’t actually work,” said Douglas Keszler, a distinguished professor of chemistry at OSU. “We didn’t really know why, so we decided to take another look at it. In this process we’ve discovered some different materials that are similar to pyrite, with most of the advantages but none of the problems.

“There’s still work to do in integrating these materials into actual solar cells,” Keszler said. “But fundamentally, it’s very promising. This is a completely new insight we got from studying fool’s gold.”

Pyrite was of interest early in the solar energy era because it had an enormous capacity to absorb solar energy, was abundant, and could be used in layers 2,000 times thinner than some of its competitors, such as silicon. However, it didn’t effectively convert the solar energy into electricity.

In the new study, the researchers found out why. In the process of creating solar cells, which takes a substantial amount of heat, pyrite starts to decompose and forms products that prevent the creation of electricity.

Based on their new understanding of exactly what the problem was, the research team then sought and found compounds that had the same capabilities of pyrite but didn’t decompose. One of them was iron silicon sulfide.

“Iron is about the cheapest element in the world to extract from nature, silicon is second, and sulfur is virtually free,” Keszler said. “These compounds would be stable, safe, and would not decompose. There’s nothing here that looks like a show-stopper in the creation of a new class of solar energy materials.”

Work to continue the development of the materials and find even better ones in the same class will continue at the National Renewable Energy Laboratory in Colorado, which collaborated on this research.

The work was done at the Center for Inverse Design, a collaborative initiative of the College of Science and College of Engineering at OSU, formed two years ago with a $3 million grant from the U.S. Department of Energy. It was one of the new Energy Frontier Research Centers set up through a national, $777 million federal program to identify energy solutions for the future.

The OSU program is different from traditional science, in which the process often is to discover something and then look for a possible application. In this center, researchers start with an idea of what they want and then try to find the kind of materials, atomic structure or even construction methods it would take to achieve it.

Finding cheap, environmentally benign and more efficient materials for solar energy is necessary for the future growth of the industry, researchers said.

“The beauty of a material such as this is that it is abundant, would not cost much and might be able to produce high-efficiency solar cells,” Keszler said. “That’s just what we need for more broad use of solar energy.”

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Story Source:

The above story is reprinted from materials provided by Oregon State University.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Liping Yu, Stephan Lany, Robert Kykyneshi, Vorranutch Jieratum, Ram Ravichandran, Brian Pelatt, Emmeline Altschul, Heather A. S. Platt, John F. Wager, Douglas A. Keszler, Alex Zunger. Iron Chalcogenide Photovoltaic Absorbers. Advanced Energy Materials, 2011; 1 (5): 748 DOI: 10.1002/aenm.201100351

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.

 

‘Fool’s gold’ aids discovery of new options for cheap, benign solar energy

November 28, 2011 at 7:56 pm | Solar Blog | No comment

 

ScienceDaily (Nov. 28, 2011) — Pyrite, better known as “fool’s gold,” was familiar to the ancient Romans and has fooled prospectors for centuries — but has now helped researchers at Oregon State University discover related compounds that offer new, cheap and promising options for solar energy.

These new compounds, unlike some solar cell materials made from rare, expensive or toxic elements, would be benign and could be processed from some of the most abundant elements on Earth. Findings on them have been published in Advanced Energy Materials, a professional journal.

Iron pyrite itself has little value as a future solar energy compound, the scientists say, just as the brassy, yellow-toned mineral holds no value compared to the precious metal it resembles. But for more than 25 years it was known to have some desirable qualities that made it of interest for solar energy, and that spurred the recent research.

The results have been anything but foolish.

“We’ve known for a long time that pyrite was interesting for its solar properties, but that it didn’t actually work,” said Douglas Keszler, a distinguished professor of chemistry at OSU. “We didn’t really know why, so we decided to take another look at it. In this process we’ve discovered some different materials that are similar to pyrite, with most of the advantages but none of the problems.

“There’s still work to do in integrating these materials into actual solar cells,” Keszler said. “But fundamentally, it’s very promising. This is a completely new insight we got from studying fool’s gold.”

Pyrite was of interest early in the solar energy era because it had an enormous capacity to absorb solar energy, was abundant, and could be used in layers 2,000 times thinner than some of its competitors, such as silicon. However, it didn’t effectively convert the solar energy into electricity.

In the new study, the researchers found out why. In the process of creating solar cells, which takes a substantial amount of heat, pyrite starts to decompose and forms products that prevent the creation of electricity.

Based on their new understanding of exactly what the problem was, the research team then sought and found compounds that had the same capabilities of pyrite but didn’t decompose. One of them was iron silicon sulfide.

“Iron is about the cheapest element in the world to extract from nature, silicon is second, and sulfur is virtually free,” Keszler said. “These compounds would be stable, safe, and would not decompose. There’s nothing here that looks like a show-stopper in the creation of a new class of solar energy materials.”

Work to continue the development of the materials and find even better ones in the same class will continue at the National Renewable Energy Laboratory in Colorado, which collaborated on this research.

The work was done at the Center for Inverse Design, a collaborative initiative of the College of Science and College of Engineering at OSU, formed two years ago with a $3 million grant from the U.S. Department of Energy. It was one of the new Energy Frontier Research Centers set up through a national, $777 million federal program to identify energy solutions for the future.

The OSU program is different from traditional science, in which the process often is to discover something and then look for a possible application. In this center, researchers start with an idea of what they want and then try to find the kind of materials, atomic structure or even construction methods it would take to achieve it.

Finding cheap, environmentally benign and more efficient materials for solar energy is necessary for the future growth of the industry, researchers said.

“The beauty of a material such as this is that it is abundant, would not cost much and might be able to produce high-efficiency solar cells,” Keszler said. “That’s just what we need for more broad use of solar energy.”

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Story Source:

The above story is reprinted from materials provided by Oregon State University.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Liping Yu, Stephan Lany, Robert Kykyneshi, Vorranutch Jieratum, Ram Ravichandran, Brian Pelatt, Emmeline Altschul, Heather A. S. Platt, John F. Wager, Douglas A. Keszler, Alex Zunger. Iron Chalcogenide Photovoltaic Absorbers. Advanced Energy Materials, 2011; 1 (5): 748 DOI: 10.1002/aenm.201100351

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.

 

Nanoparticle electrode for batteries could make grid-scale power storage feasible

November 23, 2011 at 11:19 pm | Solar Blog | No comment

 

ScienceDaily (Nov. 23, 2011) — Stanford researchers have used nanoparticles of a copper compound to develop a high-power battery electrode that is so inexpensive to make, so efficient and so durable that it could be used to build batteries big enough for economical large-scale energy storage on the electrical grid — something researchers have sought for years.

The research offers a promising solution to the problem of sharp drop-offs in the output of wind and solar systems with minor changes in weather conditions.

The sun doesn’t always shine and the breeze doesn’t always blow and therein lie perhaps the biggest hurdles to making wind and solar power usable on a grand scale. If only there were an efficient, durable, high-power, rechargeable battery we could use to store large quantities of excess power generated on windy or sunny days until we needed it. And as long as we’re fantasizing, let’s imagine the battery is cheap to build, too.

Now Stanford researchers have developed part of that dream battery, a new electrode that employs crystalline nanoparticles of a copper compound.

In laboratory tests, the electrode survived 40,000 cycles of charging and discharging, after which it could still be charged to more than 80 percent of its original charge capacity. For comparison, the average lithium ion battery can handle about 400 charge/discharge cycles before it deteriorates too much to be of practical use.

“At a rate of several cycles per day, this electrode would have a good 30 years of useful life on the electrical grid,” said Colin Wessells, a graduate student in materials science and engineering who is the lead author of a paper describing the research, published this week in Nature Communications.

“That is a breakthrough performance — a battery that will keep running for tens of thousands of cycles and never fail,” said Yi Cui, an associate professor of materials science and engineering, who is Wessell’s adviser and a coauthor of the paper.

The electrode’s durability derives from the atomic structure of the crystalline copper hexacyanoferrate used to make it. The crystals have an open framework that allows ions — electrically charged particles whose movements en masse either charge or discharge a battery — to easily go in and out without damaging the electrode. Most batteries fail because of accumulated damage to an electrode’s crystal structure.

Because the ions can move so freely, the electrode’s cycle of charging and discharging is extremely fast, which is important because the power you get out of a battery is proportional to how fast you can discharge the electrode.

To maximize the benefit of the open structure, the researchers needed to use the right size ions. Too big and the ions would tend to get stuck and could damage the crystal structure when they moved in and out of the electrode. Too small and they might end up sticking to one side of the open spaces between atoms, instead of easily passing through. The right-sized ion turned out to be hydrated potassium, a much better fit compared with other hydrated ions such as sodium and lithium.

“It fits perfectly — really, really nicely,” said Cui. “Potassium will just zoom in and zoom out, so you can have an extremely high-power battery.”

The speed of the electrode is further enhanced because the particles of electrode material that Wessell synthesized are tiny even by nanoparticle standards — a mere 100 atoms across.

Those modest dimensions mean the ions don’t have to travel very far into the electrode to react with active sites in a particle to charge the electrode to its maximum capacity, or to get back out during discharge.

A lot of recent research on batteries, including other work done by Cui’s research group, has focused on lithium ion batteries, which have a high energy density — meaning they hold a lot of charge for their size. That makes them great for portable electronics such as laptop computers.

But energy density really doesn’t matter as much when you’re talking about storage on the power grid. You could have a battery as big as a house since it doesn’t need to be portable. Cost is a greater concern.

Some of the components in lithium ion batteries are expensive and no one knows for certain that making the batteries on a scale for use in the power grid will ever be economical.

“We decided we needed to develop a ‘new chemistry’ if we were going to make low-cost batteries and battery electrodes for the power grid,” Wessells said.

The researchers chose to use a water-based electrolyte, which Wessells described as “basically free compared to the cost of an organic electrolyte” such as is used in lithium ion batteries. They made the battery electric materials from readily available precursors such as iron, copper, carbon and nitrogen — all of which are extremely inexpensive compared with lithium.

The sole significant limitation to the new electrode is that its chemical properties cause it to be usable only as a high voltage electrode. But every battery needs two electrodes — a high voltage cathode and a low voltage anode — in order to create the voltage difference that produces electricity. The researchers need to find another material to use for the anode before they can build an actual battery.

But Cui said they have already been investigating various materials for an anode and have some promising candidates.

Even though they haven’t constructed a full battery yet, the performance of the new electrode is so superior to any other existing battery electrode that Robert Huggins, an emeritus professor of materials science and engineering who worked on the project, said the electrode “leads to a promising electrochemical solution to the extremely important problem of the large number of sharp drop-offs in the output of wind and solar systems” that result from events as simple and commonplace as a cloud passing over a solar farm.

Cui and Wessells noted that other electrode materials have been developed that show tremendous promise in laboratory testing but would be difficult to produce commercially. That should not be a problem with their electrode.

Wessells has been able to readily synthesize the electrode material in gram quantities in the lab. He said the process should easily be scaled up to commercial levels of production.

“We put chemicals in a flask and you get this electrode material. You can do that on any scale,” he said.

“There are no technical challenges to producing this on a big-enough scale to actually build a real battery.”

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Story Source:

The above story is reprinted from materials provided by Stanford University. The original article was written by Louis Bergeron.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Colin D. Wessells, Robert A. Huggins, Yi Cui. Copper hexacyanoferrate battery electrodes with long cycle life and high power. Nature Communications, 2011; 2: 550 DOI: 10.1038/ncomms1563

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.

 

New material can enhance energy, computer, lighting technologies

November 16, 2011 at 8:47 pm | Solar Blog | No comment

 

ScienceDaily (Nov. 16, 2011) — Arizona State University researchers have created a new compound crystal material that promises to help produce advances in a range of scientific and technological pursuits.

ASU electrical engineering professor Cun-Zheng Ning says the material, called erbium chloride silicate, can be used to develop the next generations of computers, improve the capabilities of the Internet, increase the efficiency of silicon-based photovoltaic cells to convert sunlight into electrical energy, and enhance the quality of solid-state lighting and sensor technology.

Ning’s research team of team of students and post-doctoral degree assistants help synthesize the new compound in ASU’s Nanophotonics Lab in the School of Electrical, Computer and Energy Engineering, one of the university’s Ira A. Fulton Schools of Engineering.

The lab’s erbium research is supported by the U.S. Army Research Office and U.S. Air Force Office of Scientific Research. Details about the new compound are reported in the Optical Materials Express on the website of the Optical Society of America.

The breakthrough involves the first-ever synthesis of a new erbium compound in the form of a single-crystal nanowire, which has superior properties compared to erbium compounds in other forms.

Erbium is one of the most important members of the rare earth family in the periodic table of chemical elements. It emits photons in the wavelength range of 1.5 micrometers, which are used in the optical fibers essential to high-quality performance of the Internet and telephones.

Erbium is used in doping optical fibers to amplify the signal of the Internet and telephones in telecommunications systems. Doping is the term used to describe the process of inserting low concentrations of various elements into other substances as a way to alter the electrical or optical properties of the substances to produce desired results. The elements used in such processes are referred to as dopants.

“Since we could not dope as many erbium atoms in a fiber as we wish, fibers had to be very long to be useful for amplifying an Internet signal. This makes integrating Internet communications and computing on a chip very difficult,” Ning explains.

“With the new erbium compound, 1,000 times more erbium atoms are contained in the compound. This means many devices can be integrated into a chip-scale system,” he says. “Thus the new compound materials containing erbium can be integrated with silicon to combine computing and communication functionalities on the same inexpensive silicon platform to increase the speed of computing and Internet operation at the same time.”

Erbium materials can also be used to increase the energy-conversion efficiency of silicon solar cells.

Silicon does not absorb solar radiation with wavelengths longer than 1.1 microns, which results in waste of energy — making solar cells less efficient.

Erbium materials can remedy the situation by converting two or more photons carrying small amounts of energy into one photon that is carrying a larger amount of energy. The single, more powerful photon can then be absorbed by silicon, thus increasing the efficiency of solar cells.

Erbium materials also help absorb ultraviolet light from the sun and convert it into photons carrying small amounts of energy, which can then be more efficiently converted into electricity by silicon cells. This color-conversion function of turning ultraviolet light into other visible colors of light is also important in generating white light for solid-state lighting devices.

While erbium’s importance is well-recognized, producing erbium materials of high quality has been challenging, Ning says.

The standard approach is to introduce erbium as a dopant into various host materials, such as silicon oxide, silicon, and many other crystals and glasses.

“One big problem has been that we have not been able to introduce enough erbium atoms into crystals and glasses without degrading optical quality, because too many of these kinds of dopants would cluster, which lowers the optical quality,” he says.

What is unique about the new erbium material synthesized by Ning’s group is that erbium is no longer randomly introduced as a dopant. Instead, erbium is part of a uniform compound and the number of erbium atoms is a factor of 1,000 more than the maximum amount that can be introduced in other erbium-doped materials.

Increasing the number of erbium atoms provides more optical activity to produce stronger lighting. It also enhances the conversion of different colors of light into white light to produce higher-quality solid-state lighting and enables solar cells to more efficiently convert sunlight in electrical energy.

In addition, since erbium atoms are organized in a periodic array, they do not cluster in this new compound. The fact that the material has been produced in a high-quality single-crystal form makes the optical quality superior to the other doped materials, Ning says.

Like many scientific discoveries, the synthesis of this new erbium material was made somewhat by accident.

“Similar to what other researchers are doing, we were originally trying to dope erbium into silicon nanowires. But the characteristics demonstrated by the material surprised us,” he says. “We got a new material. We did not know what it was, and there was no published document that described it. It took us more than a year to finally realize we got a new single-crystal material no one else had produced.”

Ning and his team are now trying to use the new erbium compound for various applications, such as increasing silicon solar cell efficiency and making miniaturized optical amplifiers for chip-scale photonic systems for computers and high-speed Internet.

“Most importantly,” he says, “there are many things we have yet to learn about what can be achieved with use of the material. Our preliminary studies of its characteristics show it has many amazing properties and superior optical quality. More exciting discoveries are waiting to be made.”

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Story Source:

The above story is reprinted from materials provided by Arizona 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.

 

Why solar wind is rhombic-shaped: Temperature and energy equipartition in cosmic plasmas explained

November 15, 2011 at 3:39 pm | Solar Blog | No comment

 

ScienceDaily (Nov. 15, 2011) — Why the temperatures in the solar wind are almost the same in certain directions, and why different energy densities are practically identical, was until now not clear. With a new approach to calculating instability criteria for plasmas, Bochum researchers led by Prof. Dr. Reinhard Schlickeiser (Chair for Theoretical Physics IV) have solved both problems at once. They were the first to incorporate the effects of collisions of the solar wind particles in their model. This explains experimental data significantly better than previous calculations and can also be transferred to cosmic plasmas outside our solar system.

The scientists report on their findings in Physical Review Letters.

Temperatures and pressures in the cosmic plasma

The solar wind consists of charged particles and is permeated by a magnetic field. In the analysis of this plasma, researchers investigate two types of pressure: the magnetic pressure describes the tendency of the magnetic field lines to repel each other, the kinetic pressure results from the momentum of the particles. The ratio of kinetic to magnetic pressure is called plasma beta and is a measure of whether more energy per volume is stored in magnetic fields or in particle motion. In many cosmic sources, the plasma beta is around the value one, which is the same as energy equipartition. Moreover, in cosmic plasmas near temperature isotropy prevails, i.e. the temperature parallel and perpendicular to the magnetic field lines of the plasma is the same.

Explaining satellite data

For over a decade, the instruments of the near-earth WIND satellite have gathered various solar wind data. When the plasma beta measured is plotted against the temperature anisotropy (the ratio of the perpendicular to the parallel temperature), the data points form a rhombic area around the value one. “If the values move out of the rhombic configuration, the plasma is unstable and the temperature anisotropy and the plasma beta quickly return to the stable region within the rhombus” says Prof. Schlickeiser. However, a specific, detailed explanation of this rhombic shape has, until now, been lacking, especially for low plasma beta.

Collisions in the solar wind

In previous models it was assumed that, due to the low density, the solar wind particles do not directly collide, but only interact via electromagnetic fields. “Such assumptions are, however, no longer justified for small plasma beta, since the damping due to particle collisions needs to be taken into account” explains Dipl.-Phys. Michal Michno. Prof. Schlickeiser’s group included this additional damping in their model, which led to new rhombic thresholds i.e. new stability conditions. The Bochum model explains the solar wind data measured significantly better than previous theories.

Universally valid solution

The new model can be applied to other dilute cosmic plasmas which have densities, temperatures and magnetic field strengths similar to the solar wind. Even if the diagram of temperature anisotropy and plasma beta does not have exactly the rhombic shape that the researchers found for the solar wind, the newly discovered mechanism predicts that the values are always close to one. In this way, the theory also makes an important contribution to the explanation of the energy equipartition in cosmic plasmas outside of our solar system.

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Story Source:

The above story is reprinted from materials provided by Ruhr-Universitaet-Bochum, via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. R. Schlickeiser, M. Michno, D. Ibscher, M. Lazar, T. Skoda. Modified Temperature-Anisotropy Instability Thresholds in the Solar Wind. Physical Review Letters, 2011; 107 (20) DOI: 10.1103/PhysRevLett.107.201102

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.

 

MREA PV 201.04 PV Site Assessor Training

November 15, 2011 at 8:00 am | Solar Blog | No comment

 

Course Description

Participants in this one-day course will learn how to perform a PV site assessment for a home or small business. The course will cover site assessment tools, load analysis, energy efficiency recommendations, array placement options, basic system sizing, cost estimates, and evaluating existing infrastructure on site. Participants will learn how to access online tools for solar resource analysis, PV system performance calculators, and incentives.

To receive the MREA PV Site Assessor Certificate, participants will need to complete this course, two practice site assessments, pass the written test, and pay a $50 exam fee.

Course Instructors

Kurt Nelson, SOLutions

Course Objectives

Upon completion of this course, participants will be able to:

  • Use site assessment tools
  • Size a PV system
  • Recommend a PV system type to meet a home or owner’s goals
  • Identify and recommend steps for energy efficiency
  • Perform a load analysis
  • Identify and recommend array placement options
  • Quantify the solar resource
  • Provide a general cost estimate
  • Write a PV site assessment report
  • Use web-based performance calculators
  • Provide installer and equipment vendor information

Prerequisites

PV 101 Basic Photovoltaics and basic computer skills

Continuing Education Units

  • 8.0 continuing education credits for NABCEP PV Installer Certification
  • 6.5 learning units for American Institute of Architects (AIA) – HSW/SD
  • BPI Recognized for 3.75 CEU Credits
  • 8.0 credit hours for WI Dwelling Contractor Qualifier Certification

Required Materials

  • Pencil, pen and paper
  • Calculator
  • Lunch

Location has been graciously donated by Great Lakes Aquarium for our use.

 

MREA PV 101.08 Basic Photovoltaics

November 15, 2011 at 8:00 am | Solar Blog | No comment

 

Course Description

This one-day course uses a combination of lecture and classroom activities to teach the basics of solar electric systems. Participants will learn how photovoltaic (PV) systems work, diagram the four PV system types, describe and identify components, understand the best application and limitations of each system type, define the solar window, make energy efficiency recommendations, estimate system loads, and understand the basics of PV site assessment.

Course Instructor

Kurt Nelson, SOLutions

Course Objectives

Upon completion of this course, participants will be able to:

  • Define photovoltaics
  • Explain how photovoltaic systems work
  • Diagram the four system types
  • Describe and identify components of a photovoltaic system
  • Identify the best application and limitations of each system type
  • Define the solar window
  • Use Ohm’s Law
  • Read an electric utility bill
  • Estimate electrical loads
  • Make energy efficiency recommendations
  • Identify PV mounting types
  • Explain the basics of a PV site assessment
  • Calculate system costs
  • Describe financial incentives for PV

Prerequisites

None

Continuing Education Units

  • 8.0 continuing education credits for NABCEP PV Installer Certification
  • 6.5 learning units for American Institute of Architects (AIA) – HSW/SD
  • BPI Recognized for 3.75 CEU Credits
  • 8.0 credit hours for WI Dwelling Contractor Qualifier Certification
  • 7.5 credit hours for WI Commercial Electrical Inspector Certification
  • 7.5 credit hours for WI Journeyman and Master Electrician Certification
  • 7.5 credit hours for WI UDC – Electrical Inspector Certification

Required Materials

  • Pencil, pen and paper
  • Calculator
  • Lunch

Suggested Materials

  • Text: Power from the Sun

Location has been graciously donated by Great Lakes Aquarium for our use.

 

MREA PV 211.01 PV System Inspection

November 15, 2011 at 8:00 am | Solar Blog | No comment

 

Course Description

This one-day course outlines the formal inspection of a photovoltaic system to ensure that the PV system installation conforms to professional, legal, and regional and regional electrical and mechanical standards. In this course, participants will become familiar with applicable codes and standards that ensure that system mounting and attachments, electrical calculations, grounding, labeling, and documentation meet existing codes.

This course can be taken as part of a four-day progression along with PV 207 PV System Commissioning and Decommissioning and PV 307 PV System Commissioning Lab.

Course Instructors:

Craig Buttke, North Wind Renewable Energy

Pre-requisites:

PV 205 Intermediate PV or PV 701 Photovoltaic Technology Instructor Institute or Electrical Inspector.

Continuing Education Units:

  • 7.0 continuing education credits for NABCEP PV Installer Certification

Required Materials:

  • Pen or pencil
  • Paper
  • Calculator

 

 

A light wave of innovation to advance solar energy: Researchers adapt classic antennas to harness more power from the sun

November 10, 2011 at 8:59 pm | Solar Blog | No comment

 

ScienceDaily (Nov. 10, 2011) — Some solar devices, like calculators, only need a small panel of solar cells to function. But supplying enough power to meet all our daily needs would require enormous solar panels. And solar-powered energy collected by panels made of silicon, a semiconductor material, is limited — contemporary panel technology can only convert approximately seven percent of optical solar waves into electric current.

Profs. Koby Scheuer, Yael Hanin and Amir Boag of Tel Aviv University’s Department of Physical Electronics and its innovative new Renewable Energy Center are now developing a solar panel composed of nano-antennas instead of semiconductors. By adapting classic metallic antennas to absorb light waves at optical frequencies, a much higher conversion rate from light into useable energy could be achieved. Such efficiency, combined with a lower material cost, would mean a cost-effective way to harvest and utilize “green” energy.

The technology was recently presented at Photonics West in San Francisco and published in the conference proceedings.

Receiving and transmitting green energy

Both radio and optical waves are electromagnetic energy, Prof. Scheuer explains. When these waves are harvested, electrons are generated that can be converted into electric current. Traditionally, detectors based on semiconducting materials like silicon are used to interface with light, while radio waves are captured by antenna.

For optimal absorption, the antenna dimensions must correspond to the light’s very short wavelength — a challenge in optical frequencies that plagued engineers in the past, but now we are able to fabricate antennas less than a micron in length. To test the efficacy of their antennas, Prof. Scheuer and his colleagues measured their ability to absorb and remit energy. “In order to function, an antenna must form a circuit, receiving and transmitting,” says Prof. Scheuer, who points to the example of a cell phone, whose small, hidden antenna both receives and transmits radio waves in order to complete a call or send a message.

By illuminating the antennas, the researchers were able to measure the antennas’ ability to re-emit radiation efficiently, and determine how much power is lost in the circuit — a simple matter of measuring the wattage going in and coming back out. Initial tests indicate that 95 percent of the wattage going into the antenna comes out, meaning that only five percent is wasted.

According to Prof. Scheuer, these “old school” antennas also have greater potential for solar energy because they can collect wavelengths across a much broader spectrum of light. The solar spectrum is very broad, he explains, with UV or infrared rays ranging from ten microns to less than two hundred nanometers. No semiconductor can handle this broad a spectrum, and they absorb only a fraction of the available energy. A group of antennas, however, can be manufactured in different lengths with the same materials and process, exploiting the entire available spectrum of light.

When finished, the team’s new solar panels will be large sheets of plastic which, with the use of a nano-imprinting lithography machine, will be imprinted with varying lengths and shapes of metallic antennas.

Improving solar power’s bottom line

The researchers have already constructed a model of a possible solar panel. The next step, says Prof. Scheuer, is to focus on the conversion process — how electromagnetic energy becomes electric current, and how the process can be improved.

The goal is not only to improve the efficiency of solar panels, but also to make the technology a viable option in terms of cost. Silicon is a relatively inexpensive semiconductor, but in order to obtain sufficient power from antennas, you need a very large panel — which becomes expensive. Green energy sources need to be evaluated not only by what they can contribute environmentally, but also the return on every dollar invested, Prof. Scheuer notes. “Our antenna is based on metal — aluminium and gold — in very small quantities. It has the potential to be more efficient and less expensive.”

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