September 03, 2012
Credit: Silent Falcon UAS Technologies
The thought of solar cells brings to mind the image of solid blocks of flat photovoltaic panels extending in rigid wings from a satellite or bolted to the roof of a building. Now picture a solar panel so thin and flexible that it can be rolled up and molded like wallpaper around fuselages, wings or any other shape.
This is the breakthrough developed by Thornton, Colo.-based Ascent Solar Technologies, which earned a place in Time magazine's Top 50 inventions of 2011 for its innovation. With obvious applications to aerospace, where affordable solar energy is always at a premium—particularly in space or the upper reaches of the atmosphere—the wider uses of the technology are bounded only by the imagination. The latest commercial use of the company's thin-film technology, for example, is in an integrated protective case for the Apple iPhone which doubles as a charger.
“We started looking at thin film [photovoltaics] in the early 1990s at Martin Marietta,” says Ascent Solar Technologies' chief technology officer, Joe Armstrong. “The idea was part of making satellites less expensive to launch and, although the vehicles got smaller and technology got better in terms of power storage, affordable [photo]voltaics was the one thing that didn't seem to make any progress.”
A lightweight semiconductor material called CIGS (copper, indium, gallium and selenium) offered “the best opportunity in terms of headroom and could be flexible,” says Armstrong. The CIGS was combined with a plastic substrate that enables the photovoltaic (PV) panels to be curved or shaped around uneven surfaces.
“We worked with the government, the Defense Advanced Research Projects Agency, the U.S. Air Force and a lot of major players. We got the technology to a certain level and found the partners to bring it forward,” he adds. Ascent Solar was spun off from an incubator company in 2005 and went through a Nasdaq Global Market initial public offering in July 2006. “Our goal was to demonstrate the capability to commercially manufacture monolithically integrated modules,” Armstrong says.
“We focused very specifically on flexible technology, and our key advantage is our ability to take the same material and apply it to a variety of markets—and to change direction as necessary.” Compared to other flexible PV products, Ascent's solar technology for terrestrial applications such as UAVs has the highest power density at 85 watts per square meter and the best power-to-weight ratio of 48 watts per kilogram. For space applications, the PV's module-specific power is 500-1,100 watts per kilogram, depending on the array design.
Sustaining its culture of innovation is not a problem, according to Armstrong. “It is an exciting place to work in that it's a different technology to that which other folks are working on. We are a development company and we took this technology literally from the lab to production. As a result, there are always challenges—so we are pretty heavily involved in R&D. There is innovation all the way down the line,” he says. The company has “a certain degree of fundamental R&D going on, but the idea is to keep in touch with academia and the national labs,” he adds.