Unplug that Charger – Solar Power is Ready to Shine

Congress just passed a $787 billion economic stimulus plan tonight that promises more than $50 billion for renewable energy and efficiency projects, high-tech batteries, and smart, green technology.

Scientists and clean tech firms everywhere are hoping for a piece of it.

The stimulus plan "will catapult the U.S. to be the world's largest solar market by the end of 2010," Suvi Sharma, CEO of solar-cell maker Solaria, told the Mercury News.

Cell phone giants Samsung and LG both jumped on the excitement earlier today and announced that they would soon launch their first solar-powered cell phones. They didn't release detailed specs or prices, but Samsung boasted that its touch-screen Blue Earth phone's embedded solar panel will be able to generate enough power "to call anytime anywhere."

The giants won't be the first to market with a solar phone. The original solar phone, from Hi-Tech Wealth, went on sale a year and a half ago in China. It gets about 40 minutes of talk time out of an hour of direct sunlight, but it faced a common problem for would-be solar-powered gadgets: price. It started at over $500.

While solar-powered calculators and rooftop solar panels have been around for years, scientists are only now beginning to master the challenges of building affordable solar power into energy-hungry devices that can take a beating in our purses, backpacks and pockets.

To make solar power the norm for a gadget-obsessed world, we will have to develop solar technology that is inexpensive, durable, flexible and, at the same time, powerful enough to keep the batteries charged.

Scientists have been working on those challenges at several universities and corporate laboratories around the world. With Washington's new-found respect and support for science, their advancements in solar technology could start lowering the prices soon.

Most solar technology on the market today uses one of two types of materials:

Polymer material is used to power small devices such as solar calculators. It has two distinct problems: lousy energy efficiency – it only absorbs 5 to 6 percent of the solar power hitting it – and a limited life span. Polymer solar cells have probably gone as far as they can in terms of efficiency simply because of their atomic structure.

Silicon is found in rooftop solar panels and in the growing number of portable solar chargers. Silicon solar panels are far more efficient than polymers. They absorb more than 20 percent of the energy hitting them, but the material needed to make them is expensive and the panels are brittle. "You cannot carry them easily because they break," says Yonggang Huang, a Northwestern University engineering professor at the forefront of solar technology.

Huang and engineering professor John Rogers of the University of Illinois invented a new technique that takes the best elements of both. They were able to create thin, silicon-based solar cells that are "as flexible as polymer but as efficient as silicon."

The flexible solar cell material could be worn on a running jacket and store enough power to charge a cell phone, Huang says. The cells are also transparent. "You could use it on a car body, on windows. It's flexible, so you could use it on a backpack."

The flexible silicon solar cells also require only a fraction of the thickness of silicon found in typical solar panels, which significantly lowers the cost to produce them.

The Department of Energy's National Renewable Energy Laboratory (NREL) is working on perfecting processes used to create another form of flexible solar material, thin-film solar cells. NREL last year reached 19.9 percent effeciency with its copper indium gallium diselenide thin-film technology. Other thin-film solar cell efforts are working with silicon and printing processes that use semiconductor ink.

University of Arizona chemistry professor Neal Armstrong also envisions solar cells covering cars to power the MP3 players, GPS systems and cell phones inside. To do that, he is focusing on an even less expensive method – using red and blue organic dyes that transmit electric current in sunlight.

The materials are cheap enough that cell phone manufacturers could give them away, Armstrong says. However, they are far less energy efficient than silicon – they likely won't absorb more than 10 percent of the sunlight hitting them, and so far they haven't come close to that level. As Armstrong told the Arizona Star last week:

"Our challenge is to get the efficiency up, keep the cost down and make sure they last long enough to get your money's worth."

Could these new developments spell the end of the wall warts? No more chargers stuck in sockets waiting for their phones? Samsung is indicating no. It plans to include a charger, albeit a low-energy charger, with its new solar phone.

Today's cell phone chargers don't sap as much energy as commercials might lead us to believe – about 5 watts when charging and about half a watt idle according to some estimates. Armstrong calculates that about half a pound of CO2 is released every time a cell phone is charged from a coal-fired power plant.

The energy use might not be much, but why tap a coal-powered grid at all if you don't have to?

 

See also:

Smart Grid Fever Strikes Silicon Valley

For First Solar, the Milestone of Grid Parity Achieved?

With $300 Million More, Nanosolar Secures Place in Solar Big League

Bush Administration Freezes Solar Projects to Study Environmental Impact of Collecting Sunshine in the Desert

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