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.