Tiny Wires Reach Up to Grab Solar Energy

April 9, 2013 by  
Filed under Green Energy News

The world of solar panels, up to now, has been essentially flat. A Swedish company is proposing to change that, boosting electricity production by as much as 25%.

Sol Voltaics, as the company is called, plans to exploit a novel way to create microscopic filaments called nanowires out of gallium arsenide. The material has long been used to make solar cells and has advantages over other materials like silicon, but is also considerably more expensive.

By suspending the tiny wires in a liquid and coating a surface with it–in a process that makes the wires point upwards, like whiskers or blades of grass–the company claims it can create panels that generate electricity from sunlight using much less gallium arsenide than would normally be required.

“It takes less that a gram of the material to cover a square meter,” says David Epstein, a veteran Silicon Valley entrepreneur who was recruited to be CEO of Sol Voltaics.

The approach could be used to make entirely new solar panels, by coating a surface like a sheet of glass, Epstein says. But even more electricity could be generated for a given surface area by placing a coating on existing solar panels, he says.

The 25% boost in efficiency might be used to let fewer panels generate a given amount of electricity. Conversely, more electricity might emanate from the same number of panels; a 200-watt panel, for example, could become a 250-watt panel after the coating is applied, the company says. There would be an upfront cost, of course, but it would be tiny compared with the benefits, Epstein says.

Sol Voltaics was founded by Lars Samuelson, a professor at Lund University in Sweden who is a widely published authority in the field known as nanotechnology. Its work is based on an unusual  production process dubbed aerotaxy.

Chip makers and other manufacturers routinely use gases to deposit materials on stationary surfaces like silicon wafers. With aerotaxy, by contrast, nanowires are continuously formed on tiny gold balls as they are floating along down a gas-filled chamber, Epstein says.

At the end of the stream, they are collected and stored in a liquid, which could be applied in a process akin to inkjet printing. Rather than make solar panels itself–a troubled business at the moment because of a supply glut–Sol Voltaics wants to set up plants to sell the liquid to existing panel makers to make their products more efficient.

“We call it ink,” Epstein says. “We are going to be the ink factory.”

So far, Sol Voltaics has only demonstrated solar cells using nanowires made from the material indium phosphide. But it expects to demonstrate cells with gallium arsenide by the end of 2013, with commercial production beginning in high volume in 2016.

The company has raised $11 million from Swedish investors so far and is expecting another $10 million to $20 million this year. It expects to require less than $50 million to get to high-volume production.

Sol Voltaics is not the only organization talking about gallium arsenide nanowires.

VentureBeat on Monday reported that Anna Fontcuberta i Morral, a researcher in the semiconductor lab at Ecole Polytechnique Fédérale de Lausanne in Lausanne, Switzerland, has published a paper along with other workers discussing similar techniques in the journal Nature Photonics.


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