[amor de cosmos]

UCLA researchers double efficiency of novel solar cell
Device could coat windows, smartphone screens with energy-harvesting material
By Bill Kisliuk
July 29, 2013

Nearly doubling the efficiency of a breakthrough photovoltaic cell they created last year, UCLA researchers have developed a two-layer, see-through solar film that could be placed on windows, sunroofs, smartphone displays and other surfaces to harvest energy from the sun.

The new device is composed of two thin polymer solar cells that collect sunlight and convert it to power. It's more efficient than previous devices, the researchers say, because its two cells absorb more light than single-layer solar devices, because it uses light from a wider portion of the solar spectrum, and because it incorporates a layer of novel materials between the two cells to reduce energy loss.

While a tandem-structure transparent organic photovoltaic (TOPV) device developed at UCLA in 2012 converts about 4 percent of the energy it receives from the sun into electric power (its "conversion rate"), the new tandem device — which uses a combination of transparent and semi-transparent cells — achieves a conversion rate of 7.3 percent.

Researchers led by Yang Yang, the Carol and Lawrence E. Tannas, Jr., Professor of Engineering at the UCLA Henry Samueli School of Engineering and Applied Science, said the new cells could serve as a power-generating layer on windows and smartphone displays without compromising users' ability to see through the surface. The cells can be produced so that they appear light gray, green or brown, and so can blend with the color and design features of buildings and surfaces.

The research was published online July 26 by Energy & Environmental Science, a Royal Society of Chemistry journal, and it will appear later in a published edition of the journal.

http://newsroom.ucla.edu/portal/ucla...cy-247383.aspx

A new way to trap light
MIT researchers discover a new phenomenon that could lead to new types of lasers and sensors.
David L. Chandler, MIT News Office
July 10, 2013

There are several ways to “trap” a beam of light — usually with mirrors, other reflective surfaces, or high-tech materials such as photonic crystals. But now researchers at MIT have discovered a new method to trap light that could find a wide variety of applications.

The new system, devised through computer modeling and then demonstrated experimentally, pits light waves against light waves: It sets up two waves that have the same wavelength, but exactly opposite phases — where one wave has a peak, the other has a trough — so that the waves cancel each other out. Meanwhile, light of other wavelengths (or colors) can pass through freely.

The researchers say that this phenomenon could apply to any type of wave: sound waves, radio waves, electrons (whose behavior can be described by wave equations), and even waves in water.

The discovery is reported this week in the journal Nature by professors of physics Marin Soljačić and John Joannopoulos, associate professor of applied mathematics Steven Johnson, and graduate students Chia Wei Hsu, Bo Zhen, Jeongwon Lee and Song-Liang Chua.

“For many optical devices you want to build,” Soljačić says — including lasers, solar cells and fiber optics — “you need a way to confine light.” This has most often been accomplished using mirrors of various kinds, including both traditional mirrors and more advanced dielectric mirrors, as well as exotic photonic crystals and devices that rely on a phenomenon called Anderson localization. In all of these cases, light’s passage is blocked: In physics terminology, there are no “permitted” states for the light to continue on its path, so it is forced into a reflection.

http://web.mit.edu/newsoffice/2013/a...ight-0710.html

Solar Shipment Index shows June upswing in global PV market
1 August 2013

Chinese and Taiwanese photovoltaic manufacturers are enjoying a warm summer of demand, according to new index from Bloomberg New Energy Finance

London and New York: The world solar photovoltaic industry, dogged by overcapacity and consolidation in recent years, saw a pick-up in shipments as well as firmer prices in June. So reveals Bloomberg New Energy Finance’s new Solar Shipments Index, based on a survey of leading manufacturers in the PV supply chain.

The booming Japanese market, expected to total between 6.9 and 9.4GW of new-build PV in 2013, was one major driver for the June upswing; another was a rush to ship products to the European Union before a higher rate of preliminary anti-dumping tariffs on Chinese products was expected to come into effect on 6 August.

The Solar Shipments Index showed that leading Chinese cell makers made shipments corresponding to 116% of their average manufacturing capacity utilisation in the month of June 2013, with Chinese module makers averaging 99% and Taiwanese cell makers 84%.

http://about.bnef.com/press-releases...bal-pv-market/

29.07.2013
The best of two worlds: Solar hydrogen production breakthrough

Using a simple solar cell and a photo anode made of a metal oxide, HZB and TU Delft scientists have successfully stored nearly five percent of solar energy chemically in the form of hydrogen. This is a major feat as the design of the solar cell is much simpler than that of the high-efficiency triple-junction cells based on amorphous silicon or expensive III-V semiconductors that are traditionally used for this purpose. The photo anode, which is made from the metal oxide bismuth vanadate (BiVO4) to which a small amount of tungsten atoms was added, was sprayed onto a piece of conducting glass and coated with an inexpensive cobalt phosphate catalyst. “Basically, we combined the best of both worlds,” explains Prof. Dr. Roel van de Krol, head of the HZB Institute for Solar Fuels: “We start with a chemically stable, low cost metal oxide, add a really good but simple silicon-based thin film solar cell, and – voilà – we’ve just created a cost-effective, highly stable, and highly efficient solar fuel device.”

Thus the experts were able to develop a rather elegant and simple system for using sunlight to split water into hydrogen and oxygen. This process, called artificial photosynthesis, allows solar energy to be stored in the form of hydrogen. The hydrogen can then be used as a fuel either directly or in the form of methane, or it can generate electricity in a fuel cell. One rough estimate shows the potential inherent in this technology: At a solar performance in Germany of roughly 600 Watts per square meter, 100 square meters of this type of system is theoretically capable of storing 3 kilowatt hours of energy in the form of hydrogen in just one single hour of sunshine. This energy could then be available at night or on cloudy days.

http://www.helmholtz-berlin.de/pubbi...che=en&typoid=

30th July 2013, 10:14am
Suburban sprawl to power cities of the future

A city’s suburbs could hold the solution to dwindling fuel supplies by producing enough energy to power residents’ cars and even top up power resources, pioneering new research has found.

It is commonly assumed that compact cities, with built-up central business districts and densely-populated residential areas, are more energy efficient than the low-density suburban sprawl that surrounds them, which are dependent on oil for high levels of private transport use.

In a future with photovoltaic solar panels on suburban roofs and increasing use of electric vehicles however, experts have predicted that suburbia will adopt a valuable new role – transforming from a high energy consumer into a vital power provider for the city.

Newly published research, conducted by Professor Hugh Byrd from the University of Lincoln, UK, and collaborators including Professor Basil Sharp from the New Zealand Energy Centre and experts from the University of Auckland, New Zealand, challenges the conventional theory that compact urban form offers the best solution for a sustainable city.

Instead, the team of researchers highlight the potential of suburbs for harnessing solar energy, with detached suburban houses capable of producing ten times the amount of energy created by skyscrapers and other commercial buildings.

The findings also reveal that lower density housing in suburbia not only has the greatest capacity for collecting solar energy, but also the greatest surplus after its own energy uses have been taken into account to help out city centre peak electricity loads.

Professor Byrd, from Lincoln’s School of Architecture, said: “This study challenges conventional thinking that suburbia is energy-inefficient, a belief that has become enshrined in architectural policy. In fact, our results reverse the argument for a compact city based on transport energy use, and completely change the current perception of urban sprawl.

“While a compact city may be more efficient for internal combustion engine vehicles, a dispersed city is more efficient when distributed generation of electricity by photovoltaic installations is the main energy source and electric vehicles are the principal mode of transport.

“However, if this energy contribution is to be effective, controls of new suburban development may be needed that require the installation of photovoltaic roofing, along with smart meters and appropriate charging facilities for vehicles. City planners will need to make the changes necessary to control suburban development.”

http://www.lincoln.ac.uk/news/2013/07/745.asp

Lawrence Livermore engineering team makes breakthrough in solar energy research
Kenneth K Ma, LLNL, (925)-423-7602

LIVERMORE, Calif. - The use of plasmonic black metals could someday provide a pathway to more efficient photovoltaics (PV) -- the use of solar panels containing photovoltaic solar cells -- to improve solar energy harvesting, according to researchers at Lawrence Livermore National Laboratory (LLNL).

The LLNL Materials Engineering Division (MED) research team has made breakthroughs experimenting with black metals. These nanostructured metals are designed to have low reflectivity and high absorption of visible and infrared light. The MED research team recently published their black metals research results in a cover-page article in the May issue of Applied Physics Letters titled "Plasmonic Black Metals in Resonant Nanocavities."

Authored by MED physicist and research team member Mihail Bora, the article details the work of the nanophotonics and plasmonics research team led by LLNL engineer Tiziana Bond.

It describes the team's concept of black metals, which are not classic metals but can be thought of as an extension of the black silicon concept. When silicon is treated in a certain way, such as being roughened at the nanoscale level, it traps light by multiple reflections, increasing its solar absorption. This gives the silicon a black surface that's able to better trap the full sun's wavelength spectrum.

Similarly, black metals are produced by some sort of random nanostructuring -- either in gold or silver -- without guaranteeing a full, reliable and repeatable full solar absorption. However, Bond's team developed a method to improve and control the absorption efficiency and basically turn the metals as black as they want, allowing them to increase, on demand, the absorption of a higher quantity of solar wavelengths. Her team built nanopillar structures that are trapping and absorbing all the relevant wavelengths of the entire solar spectrum.

https://www.llnl.gov/news/newsreleas...-13-07-06.html

Solar programme aims to install 5MW across 170 schools
By Peter Bennett
30 July 2013, 14:38 Updated: 30 July 2013, 15:40

The newly-formed ‘Power Your Future’ programme is aiming to install 5MW of solar on school roofs across the UK.

The programme, set up by Engynious and Winch Energy, is capable of installing solar on up to170 schools.

“For the Engynious Group, this is the largest programme and its first in the UK market to date. Our tailored solutions provide distributed energy production combined with on-site consumption, a major pillar for the world’s future energy supply”, commented Gregor Loukidis, director of Engynious Clean Power.

“Schools benefit from having an off-grid energy supply and lower cost energy than traditional energy supplies that are subject to energy price rises. By ring-fencing part of their electricity costs, schools can better manage their budgets and students gain from the teaching and learning opportunities that having solar PV on their roofs affords,” added Nick Wrigley, chairman of Winch Energy.

The solar arrays will vary in size between 20-50kWp depending on site constraints. The first installation to be successfully completed under the programme was a 50kWp installation at West Park School in July 2013.

http://www.solarpowerportal.co.uk/ne...0_schools_2356

College Solar Installation Saves $750,000 Annually
Published on 30 July 2013

An 8MW solar installation on the campus of Mercer County Community College in West Windsor, New Jersey (US) may be the largest college solar system in North America.

The 8MW solar system is located on a 45 acre parcel of land at MCCC and will save the college approximately $750,000 annually.

Patricia C. Donohue President, said the solar farm moves forward on many fronts. "The solar farm will save critical dollars and enable us to restore to our budget many cuts in programs and services we have made over the past two years. It also helps us fulfill our sustainability goals. We have committed to the American College & University Presidents' Climate Commitment (ACUPCC) with the goal of achieving carbon neutrality."

The annual electricity produced from this project will provide 70% of the power needed to run the campus and is equivalent to:

• 9,010 metric tons of CO2
• 1,767 passenger vehicles greenhouse gas emissions
• 89 acres of forest preserved from deforestation of carbon sequestered
• 1,123 homes greenhouse gas emissions

http://www.solarnovus.com/college-so...lly_N6824.html