World Record Achieved in Solar Cell Technology

A yield of 40.7% in photovoltaic solar energy has been obtained. This profit supposes a world-wide record in this type of renewable energy and also to cross the threshold of the economic yield.

Photovoltaic solar energy transform solar radiation into electricity without the mediation of a mechanical or thermal device. Generally, and to until now, they have constructed the photovoltaic solar paddles with solar cells made from semiconductors. Efficiency of a solar cell will depend on the percentage of solar energy that is transformed in electrical energy. In this way a yield of 10% means that a 10% of the energy is transformed into electricity.

A concentrator solar cell produced by Spectrolab, a Boeing company, has recently achieved a world-record conversion efficiency of 40.7 percent, establishing a new milestone in sunlight-to-electricity performance. This breakthrough may lead to systems with an installation cost of only $3 per watt, producing electricity at a cost of 8-10 cents per kilowatt/hour, making solar electricity a more cost-competitive and integral part of our nation’s energy mix.

This kind pf cells work very well using collectors above 240 suns (240 timesthe normal collection, without collector, raising its performance in the process.

Attaining a 40 percent efficient concentrating solar cell means having another technology pathway for producing cost-effective solar electricity. Almost all of today’s solar cell modules do not concentrate sunlight but use only what the sun produces naturally, what researchers call “one sun insolation,” which achieves an efficiency of 12 to 18 percent. However, by using an optical concentrator, sunlight intensity can be increased, squeezing more electricity out of a single solar cell.

The 40.7 percent cell was developed using a unique structure called a multi-junction solar cell. This type of cell achieves a higher efficiency by capturing more of the solar spectrum. In a multi-junction cell, individual cells are made of layers, where each layer captures part of the sunlight passing through the cell. This allows the cell to get more energy from the sun’s light.

Cells are expensive, but using collectors allows them to collect enough solar radiation to achieve that performance and potency witout needing a big surface coverede with cells, that is howa surface receiving a radiation of 1000 watts may produce 407 watts of electricity without being completely covered with cells. Mirrors or lenses are much cheaper. Obviously the light collecting reches another kind of limit.

For the past two decades researchers have tried to break the “40 percent efficient” barrier on solar cell devices. In the early 1980s, DOE began researching what are known as “multi-junction gallium arsenide-based solar cell devices,” multi-layered solar cells which converted about 16 percent of the sun’s available energy into electricity. In 1994, DOE’s National Renewable Energy laboratory broke the 30 percent barrier, which attracted interest from the space industry. Most satellites today use these multi-junction cells.

U.S. Government aims to win nationwide acceptance of clean solar energy technologies by 2015. By then, it is intended that America will have enough solar energy systems installed to provide power to one to two million homes, at a cost of 5 to 10 cents per kilowatt/hour. The SAI is also key component of President Bush’s Advanced Energy Initiative, which provides a 22 percent increase in research and development funding and seeks to reduce our dependence on foreign sources of oil by changing the way we power our cars, homes and businesses.

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