In a lab in Caltech, Harry Atwater holds up a plastic panel, a fraction of a millimeter thick. Even in the bright room, the surface's panel remains jet-black -- absorbing all the light that hits it.
The high-tech material is 10 times more efficient at absorbing light than the regular silicon cells that some homeowners install on their roofs to harvest the energy of the sun.
It is one of several projects that Atwater's team at Caltech is pursuing in a push to design the next generation of solar cells -- ones that are cheap, long-lasting and flexible enough to be practical for homeowners and businesses.
The idea dates back to 1839, when French physicist Alexandre-Edmond Becquerel discovered that certain materials could produce electric currents when exposed to light. The process, called the photoelectric effect, occurs when electromagnetic radiation (including visible light) is absorbed in a solid, liquid or gas. That energy transfers to electrons, allowing them to escape from their normal positions and flow, to create an electrical current.
Solar cells (solar photovoltaic devices) have been around since the 1950s. Back then, "the costs were astronomical," said Blake Jones, president of Namaste Solar, a solar electric company based in Colorado.
Improved technology has brought prices far down. And countries such as Japan and Germany have provided subsidies to bring costs down further. In the last year, the U.S. government has done similarly, issuing cash grants to consumers purchasing solar panels and more tax credits for manufacturers of renewable technologies.
Among states, California was the first to kick-start its own solar photovoltaic market by giving consumers tax credits and cash rebates for purchasing solar electric systems. Other states have followed suit. Today, California has the largest market in the U.S., followed by New Jersey and Colorado.
But though homes as well as businesses (including Google, Wal-Mart, and EBay) are increasingly using the technology, solar cells still aren't as cost-effective as other forms of energy.
The predominant type is a thin wafer made from silicon, the second most abundant element in the Earth's crust. Silicon-based solar cells have proved to be long-lasting, durable and efficient at converting sunlight into electricity.
However, to be used for solar cells, silicon needs to be purified in an expensive process.
