“These solar cells have, for the first time, surpassed the conventional light-trapping limit for absorbing materials,” says Harry Atwater, Howard Hughes Professor, professor of applied physics and materials science, and director of Caltech’s Resnick Institute, which focuses on sustainability research.

The light-trapping limit of a material refers to how much sunlight it is able to absorb. The silicon-wire arrays absorb up to 96 percent of incident sunlight at a single wavelength and 85 percent of total collectible sunlight. “We’ve surpassed previous optical microstructures developed to trap light,” he says.

Atwater and his colleagues—including Nathan Lewis, the George L. Argyros Professor and professor of chemistry at Caltech, and graduate student Michael Kelzenberg—assessed the performance of these arrays in a paper appearing in the February 14 advance online edition of the journal Nature Materials.

Atwater notes that the solar cells’ enhanced absorption is “useful absorption.”

“Many materials can absorb light quite well but not generate electricity—like, for instance, black paint,” he explains. “What’s most important in a solar cell is whether that absorption leads to the creation of charge carriers.”

The silicon wire arrays created by Atwater and his colleagues are able to convert between 90 and 100 percent of the photons they absorb into electrons—in technical terms, the wires have a near-perfect internal quantum efficiency. “High absorption plus good conversion makes for a high-quality solar cell,” says Atwater. “It’s an important advance.”

The key to the success of these solar cells is their silicon wires, each of which, says Atwater, “is independently a high-efficiency, high-quality solar cell.” When brought together in an array, however, they’re even more effective, because they interact to increase the cell’s ability to absorb light.

“Light comes into each wire, and a portion is absorbed and another portion scatters. The collective scattering interactions between the wires makes the array very absorbing,” he says.

This effect occurs despite the sparseness of the wires in the array—they cover only between 2 and 10 percent of the cell’s surface area.

“When we first considered silicon wire-array solar cells, we assumed that sunlight would be wasted on the space between wires,” explains Kelzenberg. “So our initial plan was to grow the wires as close together as possible. But when we started quantifying their absorption, we realized that more light could be absorbed than predicted by the wire-packing fraction alone. By developing light-trapping techniques for relatively sparse wire arrays, not only did we achieve suitable absorption, we also demonstrated effective optical concentration—an exciting prospect for further enhancing the efficiency of silicon-wire-array solar cells.”

Each wire measures between 30 and 100 microns in length and only 1 micron in diameter. “The entire thickness of the array is the length of the wire,” notes Atwater. “But in terms of area or volume, just 2 percent of it is silicon, and 98 percent is polymer.”

In other words, while these arrays have the thickness of a conventional crystalline solar cell, their volume is equivalent to that of a two-micron-thick film.

Since the silicon material is an expensive component of a conventional solar cell, a cell that requires just one-fiftieth of the amount of this semiconductor will be much cheaper to produce.

The composite nature of these solar cells, Atwater adds, means that they are also flexible. “Having these be complete flexible sheets of material ends up being important,” he says, “because flexible thin films can be manufactured in a roll-to-roll process, an inherently lower-cost process than one that involves brittle wafers, like those used to make conventional solar cells.”

Atwater, Lewis, and their colleagues had earlier demonstrated that it was possible to create these innovative solar cells. “They were visually striking,” says Atwater. “But it wasn’t until now that we could show that they are both highly efficient at carrier collection and highly absorbing.”

The next steps, Atwater says, are to increase the operating voltage and the overall size of the solar cell. “The structures we’ve made are square centimeters in size,” he explains. “We’re now scaling up to make cells that will be hundreds of square centimeters—the size of a normal cell.”

Atwater says that the team is already “on its way” to showing that large-area cells work just as well as these smaller versions.

In addition to Atwater, Lewis, and Kelzenberg, the all-Caltech coauthors on the Nature Materials paper, “Enhanced absorption and carrier collection in Si wire arrays for photovoltaic applications,” are postdoctoral scholars Shannon Boettcher and Joshua Spurgeon; undergraduate student Jan Petykiewicz; and graduate students Daniel Turner-Evans, Morgan Putnam, Emily Warren, and Ryan Briggs.

Their research was supported by BP and the Energy Frontier Research Center program of the Department of Energy, and made use of facilities supported by the Center for Science and Engineering of Materials, a National Science Foundation Materials Research Science and Engineering Center at Caltech. In addition, Boettcher received fellowship support from the Kavli Neuroscience Institute at Caltech.

# # #

Visit the Caltech Media Relations website at http://media.caltech.edu

This restaurant uses a solar heating system made of 1,000 hand-mirrors to cook chicken nicely in 14 minutes. Located in Cha Um, a three hour drive from Bangkok, Thailand.

From Eco-ideas.net

Part One

Part Two

2) Winery goes solar with ‘Floatovoltaics’ – SFGate

3) Palisade vineyard goes green

4) Grande River Vineyards 70% of Energy Supplied from Solar Power

5) NC vineyard uses solar power to make wine

6) J. Lohr Vineyards & Wines Announces California Sustainable Winegrowing Certification

7) Oregon winery goes way beyond organic

Most homeowners have a limited amount of space in which to place large solar panels. Your roof is a likely location. The solar panels must be installed in an area or areas of your roof that attract the most possible sunshine. There are many web sites that provide the amount of sunlight
received in any area of the world. They allow you to effectively track the sun’s position through the year.

Your solar panels must be placed where they will receive direct sunlight. An ideal spot is one that receives the sun’s rays at noon, typically the time at which your solar panels will operate with the greatest efficiency. Check to see if there are tree branches, satellite dishes or any other objects that might obstruct the path of the sun on your solar panels.

If you are installing solar panels on your roof, you will probably use a flush mount or a roof-ground mount. Flush mounts are typically used for smaller homes. Roof-ground mounts are somewhat more expensive and occupy more space, but they can be adjusted to follow the path of the sun during
the year. Roof mounts are often supported by your roof’s rafters, so use a stud finder to ascertain the position of your rafters.

When you have determined the best location for your panels, draw an outline of their position on your roof. Drill small holes in your roof/rafters before placement of the mounts to allow for easier drilling later. When you have placed the mounts in their exact locations, drill holes in the mounts and secure them with lag bolts. Secure metal rails to the roof. Attach the solar panels. Connect the panels to the electrical inverter with a conduit.

About the Author
Shannon Bell writes for Residentialsolarpanels.org a non commercial blog focused on her Photovoltaic experiences to help people understand how and why they should save energy investing in solar power. She writes on Solar Panels for Homes to help people learn how to start save energy from the scratch and then apply those experience to the next level.

Part 1

Part 2

Konarka, maker of a unique solar plastic, is an old company. In nine years, it has raised more than $150 million from the likes of Chevron, New Enterprise Associates, and the government. But it’s had little to show for it on the market. That could change with a new round of funding (its seventh) that closed today, totaling $23.8 million, according to a filing with the SEC.

Will the company finally have what it needs to step out of the shadows?

Money isn’t Konarka’s only strength. Its technology is actually pretty special too. Its patented photovoltaic material, called Power Plastic, is more efficient than even the best thin-film systems devised by the likes of First Solar and Solyndra. It is lightweight, portable, and perhaps most importantly, flexible — making it suitable for a host of interesting applications ranging from rooftops to apparel.

Click link above for complete article.

From Time.com

“This information is designed to help people who wish to use solar energy at any level, whether it be to solar power their entire home, or by starting out with one of the many new solar appliances or portable solar devices now available. ” said M.S. Rochell, editor of the site.

This information is designed to help people who wish to use solar energy at any level, whether it be to solar power their entire home, or by starting out with one of the many new solar appliances.

“I was amazed to discover some of the new ways that solar energy is being used in solar appliances, solar lighting, solar ovens, and even solar backpacks and solar powered battery chargers! There are a lot of new options now available for anyone who wants to go green and use a cleaner and more renewable form of energy.”

As more people become aware of the advantage of renewable energy, new technologies are being developed that are making solar power more widespread and more affordable.

With today’s new technologies, creating a solar power home can range from a complete installation of solar heating, cooling and lighting systems for the home, to the simple use of solar appliances, solar ovens, hot water heaters, battery chargers and other devices.

The new Affordable Solar Energy Resource Library is being expanded each month with new information that includes:

*  Solar Panel Basics
*  Building a Passive Solar Water Heater
*  Creating Your Own a Homemade Wind Generator
*  How to Build an Electric Car
*  A free online resource to find solar power grants
*  Free and low cost grant writing software
*  Additional options for financing your home solar systems
*  Energy tax incentives for businesses
*  A Free Solar Hot Air Do It Yourself Manual
*  Where to meet and share information with other DIY solar energy enthusiasts
*  Newest updates on affordable solar energy resources

About Go Green Solar Energy
Go-Green-Solar-Energy.com was founded in 2009 as an online educational resource to inspire and educate people about the benefits of using solar energy, and to assist in discovering affordable options for using solar power at home and in daily life.

“So many people see solar energy as too complicated or too expensive to use in their own lives.” said M.S. Rochell. “Our site hopes to demystify the technical complexities so that anyone who wants to use solar energy can get an idea of the possibilities, and then discover solutions that will work for their situation. ”

Currently the site includes information on a wide range of solar energy options including facts about solar energy, solar power advantages and disadvantages, where to find cheap solar power, solar panels, and the many DIY solar energy options. The editor of Go Green Solar Energy is M.S. Rochell, Ed.M, a writer, educator and avid environmental enthusiast.