IBM makes solar energy child's play

 

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By Stephen Pritchard

Posted on 16 May 2008 at 17:54

Researchers at IBM have developed a system that uses magnifying lenses to greatly concentrate the amount of solar energy reaching a cell, which could bring the price of high-capacity photovoltaic cells significantly.

The process, according to scientists at the company, is similar to the way a child might use a magnifying glass to concentrate the sun's rays on a small surface such as a piece of paper or tinder for a camp fire.

But just as a child's magnifying glass creates temperatures high enough to start a fire, so the IBM lens creates the equivalent power of 200 suns. This in turn leads to temperatures of up to 1,600 degrees Celcius - hot enough to melt stainless steel.

The technique allows a centimetre-square photovoltaic cell to capture 230 watts of energy and generate 70 watts of "usable" electricity. According to IBM, this is around five times' the output of a conventional solar cell.

However, cooling techniques developed for computer chips allowed IBM to reduce temperatures to a far more manageable 85 degrees. A liquid metal of gallium and indium compound is then used to dissipate the heat.

"We believe we can drive big change for an entire industry, and advance the basic science of solar cells," says Dr Supratik Guha, lead scientist for photovoltaics at IBM.