Newswise — These days, storage batteries account for one-fifth of the load in a typical infantryman's 45-kilogram pack, yet after a week or so they must be recharged. Soldiers in the field therefore need a portable photovoltaic system that can take in a huge gulp of sunlight and convert most of it into electricity.
The most promising effort to create such superefficient photovoltaics began in 2005, when the U.S. Defense Advanced Research Projects Agency (DARPA) funded a program that settled on a new idea--rather than merely stacking photovoltaic cells like a layer cake, with each layer tuned to absorb a different color of light, it would put the cells side by side and use prisms to direct each color to the right place. That tiling method allows for a greater variety of cells and also a more efficient wiring setup.
Aiming for a module-wide efficiency of 40 percent--versus the 30 percent then possible--the DARPA project proceeded step by step. Recently the test modules topped the 38 percent mark.
The program is clearly on the way to providing a portable, affordable source of solar power. Soldiers will be the first to reap the benefits, but not the last. With such modules in hand, it will be possible to carry the makings of a solar farm on a few trucks and set it up quickly. The result? A lot of electricity, with a relatively small footprint, not just for field soldiers but also for explorers, off-the-grid environmentalists, and isolated rural communities. A module would shine wherever the sun does.
For a faxed copy of the article ("Tapping the Power of 100 Suns," by Richard Stevenson, IEEE Spectrum, September 2012) or to arrange an interview, contact: Nancy T. Hantman, 212-419-7561, [email protected].