This solar panel can go on drones, car roofs

Source: By John Fialka, E&E News reporter • Posted: Tuesday, October 13, 2020

Researchers at the National Renewable Energy Laboratory (NREL) have come up with a new solar photovoltaic technology. It uses materials that can be curved and are flexible enough to be molded into electric vehicle rooftops, providing electricity that can extend their range between recharging.

The new technology’s market may also extend to diesel-powered refrigerated trucks, where a solar-powered roof could provide enough energy to help power the cooling system and reduce the use of diesel fuel. A third application would be for the wings and bodies of unmanned aircraft that companies use to provide internet coverage for remote areas, as well as other applications.

Joel Jean, CEO and co-founder of Swift Solar, a San Carlos, Calif., company that has licensed patents for the technology, says it has just begun to make prototype devices for a market that could extend to a variety of products “that move and fly.”

Previous PV materials such as silicon are much thicker, heavier and lack sufficient flexibility, limiting their use in applications such as car roofs, which are usually curved.

Two of Swift Solar’s co-founders are former NREL scientists who co-invented the technology.

Jean said his company calls its version of the material “Apex Flex” and describes it as a “kind of a Goldilocks product.” It approaches the power conversion efficiency levels of more exotic materials that are used on space satellites, but Apex ingredients can be obtained at a much lower price.

Goldilocks has taken almost two centuries to arrive in a form that may be “just right” for today’s mobility applications.

The basic component of Apex Flex is called perovskite. It was discovered in the Ural Mountains in 1839 by a Russian scientist named Lev Perovski. He found little use for this peculiar class of minerals that share common crystalline structures of cubes and diamondlike shapes.

But because perovskite includes a class of materials that are abundant, are relatively cheap and can potentially generate electricity more efficiently than silicon solar cells, NREL has formed a consortium of universities and startup companies to commercialize its use.

“Perovskites have the potential to become a game-changer for solar and many other fields,” Martin Keller, the director of NREL, based in Golden, Colo., recently predicted (Climatewire, April 30).

David Moore, a senior researcher at NREL, said that for car-top applications, the material costs a tiny fraction — less than one-hundredth — of the price being paid for more exotic PV products used in space-based applications.

NREL has found that the use of two layers of very thin perovskite materials on top of each other can reach a potential power conversion efficiency of 35%.

Several car companies in Asia, Europe and the U.S. are looking at applications that would incorporate solar generating material on electric vehicle rooftops.

General Motors and Toyota are among them, said Moore in an interview.

While they don’t have the energy density to fully charge the car battery, the electricity-generating roofs could give current EVs an additional 25 to 35 miles of range per day on a battery charge.

“If your average daily commute is about 20 miles, that means Monday through Friday you wouldn’t need to plug your car into a recharger,” said Moore.

For refrigeration trucks, a PV array installed on the trailer’s roof and perhaps on its sides could satisfy most of the energy needs for refrigeration. That would reduce carbon dioxide emissions and diesel pollution, major problems in large cities.

Then there is the potential use of perovskite in the curved bodies and wings of drones. Several companies are beginning to use the unmanned aircraft to extend internet coverage to remote areas, carry out climate and atmospheric experiments, or to perform imaging and surveillance tasks. The U.S. military has taken a keen interest in drones as well.

Moore estimated that there are at least “a dozen substantial startup companies planning perovskite products globally” — including four to five in the United States. “Several of those are pathways to large investment dollars,” he added.

Jean, the CEO of Swift Solar, said he was not ready to name the companies interested in its future products, but he said their potential is often underestimated.

“I think a lot of people sense that solar isn’t energy-dense enough for an electric-powered car,” but short-distance commuters, he added, “may not have to plug in at all, especially as batteries become more efficient and EVs become lighter.”

As for drone aircraft, “they can get a lot of the power they need from solar,” Jean said. “In some cases all of it.”