New connection between stacked solar cells can handle energy of 70,000 suns Fri, 09/06/2013 - 8:57am
The discovery means solar cell manufacturers can create stacked solar cells that can handle high-intensity solar energies without losing voltage at the connecting junctions, potentially improving conversion efficiency. Image: North Carolina State Univ.North Carolina State Univ. researchers have come up with a new technique for improving the connections between stacked solar cells, which should improve the overall efficiency of solar energy devices and reduce the cost of solar energy production. The new connections can allow these cells to operate at solar concentrations of 70,000 suns worth of energy without losing much voltage as “wasted energy” or heat.
Stacked solar cells consist of several solar cells that are stacked on top of one another. Stacked cells are currently the most efficient cells on the market, converting up to 45% of the solar energy they absorb into electricity.
But to be effective, solar cell designers need to ensure the connecting junctions between these stacked cells do not absorb any of the solar energy and do not siphon off the voltage the cells produce—effectively wasting that energy as heat.
“We have discovered that by inserting a very thin film of gallium arsenide into the connecting junction of stacked cells we can virtually eliminate voltage loss without blocking any of the solar energy,” says Salah Bedair, a prof. of electrical engineering at NC State and senior author of a paper describing the work.
This work is important because photovoltaic energy companies are interested in using lenses to concentrate solar energy, from one sun (no lens) to 4,000 suns or more. But if the solar energy is significantly intensified—to 700 suns or more—the connecting junctions used in existing stacked cells begin losing voltage. And the more intense the solar energy, the more voltage those junctions lose—thereby reducing the conversion efficiency.
“Now we have created a connecting junction that loses almost no voltage, even when the stacked solar cell is exposed to 70,000 suns of solar energy,” Bedair says. “And that is more than sufficient for practical purposes, since concentrating lenses are unlikely to create more than 4,000 or 5,000 suns worth of energy. This discovery means that solar cell manufacturers can now create stacked cells that can handle these high-intensity solar energies without losing voltage at the connecting junctions, thus potentially improving conversion efficiency.
“This should reduce overall costs for the energy industry because, rather than creating large, expensive solar cells, you can use much smaller cells that produce just as much electricity by absorbing intensified solar energy from concentrating lenses. And concentrating lenses are relatively inexpensive,” Bedair says.
The paper was published online in Applied Physics Letters.
Discover the true Facts about Solar Energy and turn your city Green.
Here we discuss Facts about solar energy usage, systems, plus sun related and other Interesting Facts about Solar Energy. All of which will help you with your decision whether or not to install a solar energy system at your home and make your city Green. Perhaps you'd even like to save yourself a lot of money and build your very own solar energy system.
• Solar Energy is better for the environment than traditional forms of energy. • Solar energy has many uses such as electricity production and heating of water through photovoltaic cells and directly for drying clothes. • Solar energy can also be used to heat swimming pools, power cars, for attic fans, calculators and other small appliances. • It produces lighting for indoors or outdoors. • Solar Energy is becoming more and more popular. The worldwide demand for Solar Energy is currently greater than supply.
Facts about Solar Energy usage:
• Solar Energy is measured in kilowatt-hour. 1 kilowatt = 1000 watts. • 1 kilowatt-hour (kWh) = the amount of electricity required to burn a 100 watt light bulb for 10 hours. • According to the US Department of Energy, an average American household used approximately 866-kilowatt hours per month costing them $70.68. • About 30% of our total energy consumption is used to heat water.
Sun related Facts about Solar Energy
• Sunlight travels to the earth in approximately 8 minutes from 93,000,000 miles away, at 186,282 miles per second. • The sun is also the main source of non-renewable fossil fuels (coal, gas and petroleum), which began life as plants or animals whose energy came from the sun millions of year ago. • Solar energy is responsible for weather patterns and ocean currents. • Clouds, pollution and wind can prevent the sun's rays from reaching the earth.
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