"The next generation of wearable computing will have power generation coming from the garment itself," he says.

In fact, modern warriors require approximately 240 watt-hours per day of power to charge all of their electronic devices -- too heavy a load for any batteries available today, says Rupert Pengelley, group technical editor at military analyst firm Jane's Information Group.

Pengelley says portable solar power technology is most useful in producing a trickle charge to top off batteries, but it is not as potent for recharging empty batteries.

"Solar has its place for static applications, such as being used [by soldiers] on a mountaintop" or being integrated into uniforms or the skins of vehicles, he says.

The Army is also testing shelters made of solar panels that can provide electricity for recharging laptops, satellite phones, lights, and ventilation equipment, according to Mike Coon, chief operation officer for Iowa Thin Film Technologies.

Coon says his company will deliver hundreds of tents to the Army as part of a $3.2 million contract announced on May 13. Iowa Thin Film has developed shelters in three sizes, providing from 190 watts to 2 kilowatt of power, says Coon.  For example, one hour of full sun for the smallest shelter (Quadrant) would be enough to power a laptop for five hours or a cell phone for 24 hours.

Furthermore, the solar shelters do not leave a heat signature, making it harder for an enemy to track troop movements, and they also reduce the "logistical tail" of delivering generators to remote locations, says Coon.

Coon says that Iowa Thin Film has also developed a proprietary laser scribing process for integrating the solar cells onto a flexible plastic substrate. Advances in the process can now laminate the material 24 times faster than a year ago.

The Army is also evaluating a solar battery charger from Iowa Thin Film as part of a "one-two approach" to deploying photovoltaic power sources, according to Army chemist Samuelson.

"Whatever fits the application will be pursued," Samuelson says.

According to Samuelson, the goal of the four-year project is to develop materials that can generate power for under $1 per peak watt-hour.

"We have come a long way from large rigid panels to lightweight flexible materials."

Both Iowa Thin Film and Konarka intend to commercialize their technologies after they produce products in quantity for the military. Konarka's McGahn says solar materials could be coated onto laptops or cell phones, or "iPod clothing" could recharge music players.