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Researchers Claim New Solar Panel Can Collect 90% of Sunlight From Any Angle

Andy Salisbury — Wed, 05 Nov 2008 16:20:08 -0600

With some news straight out of the “didn’t we just hear about something like this?” file (we did), some groundbreaking research has revealed that a near perfect solar panel has been created.

Scientists at the Rensselaer Polytechnic Institute have allegedly found a process that allows them to trap nine out of ten photons that hit a solar panel, providing a 90 percent collection rate. A new anti-reflective coating for the panels provides grounds for creating solar panels that don’t have to change their angle in order to collect energy.

With current technology, the photon absorption rate stands at an already impressive 67.4 percent, with the variable of whether or not the sun is actually hitting the cells. But the new cells which according to Shawn-Yu Lin, the man responsible for the project, function like a “dense forest where sunlight is ‘captured’ between the trees.” This happens through a process that not only involves the new anti-reflective coating, but also the bending of the path of the sunlight to an angle that allows maximum capture of sunlight.

With all possible variables at their best, Lin claims that the cells can capture 96.21 percent of the photons that hit their surface.

Image Credit: Unplugged Living

Breakthrough in Solar Panel Technology from a 12 Year Old?

Paul Lilly — Mon, 22 Sep 2008 16:25:26 -0500

It looks as though today's 12-year-olds are well past the days of building model volcanoes for the school science fair. And if not, well, William Yuan just put the smackdown on the competition

Yuan, a seventh grader from Oregon, set out to improve solar technology, which at the moment could be a lot more efficient. And he appears to have done just that. Yuan's project, which he calls "A Highly-Efficient 3-Dimensional Nanotube Solar Cell for Visible and UV Light," could shake up the energy industry and lead to real change into how solar energy is harnessed and distributed.

For his project, Yuan used a special solar cell capable of harnessing both visible and ultraviolet light, whereas most solar cells use either photovoltaic (only visible light), or thermal. Ultraviolet light holds interest because it can potentially provide more energy than the longer-wavelength members of the electromagnetic spectrum. And if that weren't enough, Yuan designed his project so it could stand freely in three dimensions to collect more light, and to make use of carbon nanotubes to distribute the energy more efficiently than traditional cells.

For his efforts, Yuan received a well deserved $25,000 scholarship, a fellowship at the Davidson Institute for Talent Development, and a various other awards.

What was your science project?

Everything You Need to Know About Photovoltaic Cells

Michael Brown — Mon, 22 Sep 2008 13:49:11 -0500

In one second, the nuclear fusion process taking place inside the sun produces enough energy to satisfy the needs of the earth’s population for nearly 500,000 years. Photovoltaic cells are capable of capturing some of that energy and converting it into usable electricity; unfortunately, today’s technology can’t do this very efficiently.

French physicist Edmond Becquerel first described the photovoltaic effect in 1839. He discovered that some materials were capable of producing small amounts of electricity when exposed to sunlight. The first photovoltaic cell, however, wasn’t created until 1883, and more than 70 years passed before the next major scientific advance took place, when researchers at Bell Labs developed the first crystalline silicon photovoltaic cell in 1954.

Most modern photovoltaic cells are still manufactured from silicon, the same semiconductor material used to produce GPUs, CPUs, and other integrated circuits. The majority of commercial photovoltaic cells are manufactured from crystalline silicon—either single- or poly-crystal silicon. The latter are less efficient than the former, but their lower manufacturing cost largely makes up for the conversion shortfall.

The bulk of the progress that’s been made since the 1950s stems from the efficiency at which absorbed light is converted into electricity. The Bell Labs product was capable of just 4 percent efficiency; today’s commercial products are approaching 20 percent efficiency.

Photons from the sun pass through the cell’s n-type layer to strike atoms in the p-type layer,
dislodging some of those atoms’ electrons in the process. The freed electrons move up toward the n-layer,
creating an electrical current that can be stored or service an electrical device.

The Photovoltaic Process

A photovoltaic cell is created by sandwiching two silicon wafers: an n-type layer and a p-type layer. The n-type layer exhibits a negative electrical charge and has an excess of electrons, while the p-type layer exhibits a positive electrical charge and has a shortage of electrons. The two layers are separated by an n-p junction. The cell is then attached to a backplane, a layer of metal used to physically reinforce the cell and provide an electrical contact on its bottom. A second electrical contact is placed on the top of the cell to create an electrical circuit. The cell is then treated with an anti-reflective coating to compensate for silicon’s otherwise shiny nature.

As photons—particles of light—hit the photovoltaic cell, they pass through the n-type layer and strike the p-type layer, where they are either absorbed by the silicon atoms, reflected, or pass straight through the material. Absorbed photons knock electrons loose from the silicon atoms, leaving empty “holes,” which are filled by electrons further back in the circuit. The loose electrons flow through the electrical contacts on the p-type layer to the contacts on the n-type layer. This flow of electrons produces an electric current that can be drawn off and stored in a battery or used to power an electrical device.

An array of cells is electrically connected and mounted into a frame to form a photovoltaic module. A narrow metal grid is applied to the top of the module to transport electrical energy, and a sheet of glass or plastic is placed on top to protect the cells from the environment (everything from bad weather to bird droppings and stray baseballs). A group of interconnected modules is known as an array.

Photons contain varying amounts of energy, depending on their wavelength. Within the visible spectrum, red light possesses the least amount of energy while violet light has the most. The same goes for the invisible spectrum: Infrared light possesses very little energy but ultraviolet light contains a great deal of it.

Most modern photovoltaic cells are capable of converting only high-energy photons into electrical current, which explains why mainstream solar panels are so inefficient. One of the most promising ideas for increasing the efficiency of solar energy is to stack cells with different properties on top of one another. This way, high-energy photons can be captured by a cell on the top of the stack, while lower-energy photons pass through to subsequent cells that are better suited to those photons’ wavelengths.

AC/DC

The electrical devices in your home (appliances, computers, air conditioners, lights, and so on) operate on alternating current (AC), but a solar array produces direct current (DC). The solution is to install an inverter that converts the solar array’s DC into AC. Inverters are designed to power off when there isn’t enough electrical current for them to operate, e.g., at night.

Solar panels produce the most power in the presence of direct sunlight, but they’ll produce some energy on cloudy or even rainy days. They can’t produce any juice at night, of course, so you’ll need some means of storing the electricity that they create when the sun is shining. Batteries can provide total independence from your local electric company, enabling you to potentially live “off the grid,” but this solution presents a host of environmental problems, and there’s no guarantee it will provide all the energy you’ll need. The more practical alternative is to tie your system into the electrical grid.

In a grid-tied system, you sell the excess energy your solar array generates to your local utility, and you buy back the electrical power you need for your home. With this method, the utility acts like an unlimited energy-storage system, giving you all the power you need whenever you need it. The inverter is connected to the meter the electric utility uses to measure your consumption, which means your meter will spin backward whenever you generate more than you consume.

For most households, the reward for going solar is more feel-good than financial: It could take a decade or longer to recoup the investment in even a moderate-size system. That situation is changing rapidly as the escalating cost of producing electricity from fossil fuels moves in inverse proportion to the cost of deriving energy from the sun.

Sharp Displays Solar Powered LCD at G8

Pulkit Chandna — Mon, 07 Jul 2008 09:14:22 -0500

In today’s world, people are beginning to judge each other based on their carbon karma and the power consumed by the gadgets they own. Sharp has developed a solar-powered LCD TV for all the alternative-energy patrons and parsimonious energy spenders. The LCD TV is three times more energy efficient than a regular CRT TV. And this frugal use of energy allows the LCD to completely depend on solar energy. A 26-inch prototype is on show at the upcoming Hokkaido Toyako Summit, Japan - better known as the G8 summit.

Sharp has also developed a solar cell module of the same size as the LCD TV to power it. The two will most probably be sold in conjugation, as if inseparable technological cognates. The company is targeting the product towards about 1/4th of the earth’s population which still has no or intermittent access to electricity. Many of these people might be living in such underdeveloped and impoverished places that they would be more interested in basic necessities of life than such flash technology.

But, of course, if Sharp can successfully sell this to even a very few of the world’s electricity-deprived populace, it certainly will be very happy.

Image Credit: Treehugger