Vitex, Pacific Northwest National Lab Create Impervious ‘Sandwich Bag’ To Take Solar Power Mainstream

If solar panels are ever going to generate electricity for the mass market of U.S. consumers, they will need to be embedded in a place that captures serious rays, like the roof of the average American home. Lots of scientists are trying to make solar panels thinner, lighter, flexible, and more efficient, so they can be embedded in shingles. But if this is really going to work, they’ll also need serious protection from the elements.

I got an overview of how these two technologies are coming together last week during a tour at the Pacific Northwest National Laboratory (PNNL) in Richland,WA. Two scientists there at the lab, Mark Gross and Gordon Graff, walked me through their research to create polymer films that are lean and mean enough to protect thin solar panels from the pounding of wind, rain, hail, and the occasional heavy footsteps that a roof must endure for 25 years.

This “barrier film” technology—think sandwich wrap on steroids—was spun out of the national lab a decade ago with a seed investment by Battelle, which operates the lab, and a $15 million investment from Japan-based Mitsubishi, to form a company in San Jose, CA called Vitex Systems. The first business plan could have gone in any number of directions. It identified 15 different applications for polymer material that was micron-thin, rugged, and far more impervious to oxygen and moisture than plastic. The company decided to focus on using barrier film as a coating for the next wave in lighter, thinner, more efficient flat-panel screens on TVs, laptops, and handhelds like the iPhone or BlackBerry.

But that market—for organic light-emitting diode (OLED) displays—has never really emerged because prices kept falling for the standard LCD displays, even though they are thicker and heavier, Graff says. So now Vitex and its collaborators at the national lab are investigating a new market for the barrier film—as an enabler for thin solar power panels.

“We make the sandwich bag that goes around the flat panel,” Graff says. “We make what keeps it from going to pot.”

Sounds simple, but this has required a 20-year effort in chemistry, physics, and material science. Graff and Gross were eager to tell me about how they’ve created multiple layers of polymers that are sandwiched around an inorganic layer with aluminum oxide that stops moisture from getting through. They’ve reduced the number of layers, to bring down cost, without sacrificing the needed durability.

The major competitors in making the barrier film are 3M and General Electric, Graff says, although they appear to be focusing on using it for different applications, he adds. All of the work at those companies, and what’s happening at Vitex and PNNL, is happening in parallel with work to create thin, efficient, flexible solar panels, which has been going on for years and is much more widely publicized.

There are three major thin solar photovoltaic technologies in the works, which use amorphous silicon, cadmium telluride, and something called CIGS (cadmium indium gallium selenide). The last one is the only one that’s feasible to embed in roof shingles, Graff says, so that’s the one Vitex and PNNL are looking at encasing with their barrier film. SoloPower, Miasole, and Nanosolar are a few of the better-known companies pursuing CIGS as thin-film solar material, according to VentureBeat.

So will barrier film ever hit the mainstream as a coating for thin solar panels, or will this end up struggling to get traction in the marketplace, like the coating for displays on TVs and handhelds? To hear the scientists talk, they are confident in the science, and their ability to do commercial scale-up, but they still don’t know whether it will really take off.

“It will all come down to cost,” Gross says. But his colleague Graff added, “Some form of barrier will be absolutely necessary.”

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