Popular Science - 2007 Innovation Of The Year

Nanosolar's approach combines the advantages of thin films with the power of electrically matched cells, resulting in better panel efficiency distribution and yield. Image Credit: Nanosolar

Popular Science - 2007 Innovation Of The Year

PowerSheet is “green”, aluminum silver, and inked all over and comes in as Popular Science’s 2007 Innovation Of The Year.

The PowerSheet represents a new way capturing energy from the sun. What makes the PowerSheet a real innovation is that the manufacturing process does not use the expensive and limiting method of using silicon on which to generate electricity. Basically, Nanosolar, a Silicon Valley based company, was able to sandwich thin layers of paint that has the property to convert light to electricity, in aluminum sheets and deliver solar conversion at a fraction of the cost of traditional solar panels.
Image Credit: Nanosolar

PowerSheet says it all in its name. The new “sandwiched sheet” material can be made into roofing materials, window coatings, and other exterior wraps that will have the ability to grab power from the sun. The technology breakthrough moves the cost from about $3 per watt of energy for traditional silicon solar cells, $1 per watt for coal, to as little as 30 cents a watt for the Nanosolar PowerSheet.

How It Works

This excerpted and edited from Popular Science Magazine -

The New Dawn of Solar
By MICHAEL MOYER – Popular Science - 11-22-2007

Imagine a solar panel without the panel. Just a coating, thin as a layer of paint, that takes light and converts it to electricity.
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Consider solar-powered buildings stretching not just across sunny Southern California, but through China and India and Kenya as well, because even in those countries, going solar will be cheaper than burning coal. That’s the promise of thin-film solar cells: solar power that’s ubiquitous because it’s cheap. The basic technology has been around for decades, but this year, Silicon Valley–based Nanosolar created the manufacturing technology that could make that promise a reality.

Accelerated lifetime testing is possible through specialized equipment that performs many –40°C to +85°C heat cycles per day, that exposes solar cells to intense UV light, and that exposes them to intense humidity. This has made it possible for us to study potential degradation mechanisms at accelerated time scale during product development. Image Credit: Nanosolar

The company produces its PowerSheet solar cells with printing-press-style machines that set down a layer of solar-absorbing nano-ink onto metal sheets as thin as aluminum foil, so the panels can be made for about a tenth of what current panels cost and at a rate of several hundred feet per minute.
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Cost has always been one of solar’s biggest problems. Traditional solar cells require silicon, and silicon is an expensive commodity (exacerbated currently by a global silicon shortage). What’s more, says Peter Harrop, chairman of electronics consulting firm IDTechEx, “it has to be put on glass, so it’s heavy, dangerous, expensive to ship and expensive to install because it has to be mounted.” And up to 70 percent of the silicon gets wasted in the manufacturing process. That means even the cheapest solar panels cost about $3 per watt of energy they go on to produce. To compete with coal, that figure has to shrink to just $1 per watt.

Printing is by far the simplest, highest-yield, and most capital-efficient technique for depositing thin films. Printing is extremely fast; the equipment involved is easy to use and maintain; and it works in plain air (no vacuum chamber required). Another key advantage of a printable CIGS ink is that one can print it just where one wants it to be, achieving high materials utilization of the semiconductor material. Image Credit: Nanosolar

Nanosolar’s cells use no silicon, and the company’s manufacturing process allows it to create cells that are as efficient as most commercial cells for as little as 30 cents a watt. “You’re talking about printing rolls of the stuff—printing it on the roofs of 18-wheeler trailers, printing it on garages, printing it wherever you want it,” says Dan Kammen, founding director of the Renewable and Appropriate Energy Laboratory at the University of California at Berkeley. “It really is quite a big deal in terms of altering the way we think about solar and in inherently altering the economics of solar.”

Highlight 2007: Parallel construction of factories in California and Germany commences. The product specification is finalized in close collaboration with leading customers. Image Credit: Nanosolar

In San Jose, Nanosolar has built what will soon be the world’s largest solar-panel manufacturing facility.
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Right now, the biggest question for Nanosolar is not if its products can work, but rather if it can make enough of them. California, for instance, recently launched the Million Solar Roofs initiative, which will provide tax breaks and rebates to encourage the installation of 100,000 solar roofs per year, every year, for 10 consecutive years (the state currently has 30,000 solar roofs). The company is ready for the solar boom. “Most important,” Harrop says, “Nanosolar is putting down factories instead of blathering to the press and doing endless experiments. These guys are getting on with it, and that is impressive.”
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