Industry breakthroughs are proving the viability of photovoltaic fabrics.
The University of Wisconsin–Madison may not be the first research institution you would think of for solar textiles research, but a relatively new research team is changing that low profile substantially. Marianne Fairbanks, assistant professor in the School of Human Ecology, and Trisha Andrew, assistant professor of chemistry, have developed a new technology for low-cost, lightweight solar cells.
Fairbanks comes from a textile arts and design background and had a company that made solar handbags; Andrew brings her expertise in chemistry to the project. The two quickly struck up a rapport when they met at the university, and the collaboration began.
“What I’m teaching is very much based in technique, concept, design,” Fairbanks says. “But I have a desire to push the media forward. One of the key moments for me was learning about Trisha’s (Andrew’s) research,” which she adds was an “aha” moment. “I would never have met Trisha in any other context.”
The team uses a chemical vapor deposition, a common technique, but they do it with carbon-based materials, building conductivity with a series of coatings, on the nano scale, upon the substrate. “This allows you to ‘grow’ a nanoscale solar cell,” Fairbanks says. “We can grow this device on any substrate, so we can start with whatever fabric that you want to harvest power, and lay down the series of coatings.”
“Doing chemistry in the vapor phase allows me to get this chemistry on any substrate, and allows the control needed,” Andrew says. The ability to apply this technology to any substrate is significant. With more traditional solar fabric technologies, “The substrate costs can be untenable,” she says. “But if you think of increasing the size of a curtain, that’s no big deal.”
One challenge is to improve energy collecting efficiency, which is 3-5 percent overall. Silicon solar cells are at least 12-15 percent, and as much as 25 percent, Andrew says. That’s the biggest issue for the research team now. “But we’ve definitely shown that this can work.”
The researchers will be providing more details about how the process works, and the challenges they have yet to overcome, in a featured article to come, written for Advanced Textiles Source.
“The production of solar has had a difficult time and it’s exciting to me that textiles could be the media that can push solar into a new phase,” Fairbanks says. “That’s my dream.”
The pair was funded early in the process, and Fairbanks notes the importance of the university’s support. The researchers applied for patents this spring.
Solar Cloth Co., Base Structures
Flexible, fabric-based solar cells have intrigued the energy and advanced technical textiles industries for years. Smaller, niche markets, cleverly deployed prototypes and high-fashion applications have used flexible photovoltaics (PV), often with great success. Larger-scale solar fabric applications with true commercial viability have been more elusive. Management at Solar Cloth Company (SCC), based in the U.K., says the market for flexible PV on a larger scale is there, and the technology is ready to meet demand.
SCC has been commercially active for just over a year and a half. “A fundamentally specialist PV integrator,” says CEO Mike Staplehurst, it recently merged with Base Structures, also based in the U.K., and designs, manufactures and installs fabric structures. Among them are the “Up at the O2” walkway on the Millennium Dome in London and the Ben Ainslie Racing headquarters at Portsmouth.
“The two firms will use the merger to focus on the deployment of solar carports in the U.K.,” says Staplehurst. “By combining the two companies’ expertise, it will be possible to integrate renewable energy generation into elegant fabric structures at a competitive price point and without compromising on design or aesthetics.”
It’s a working relationship that grew into a merger. “We’re PV specialists, but not necessarily the best in the world doing tensile structures,” Staplehurst says. “We realized that if you want to take a flexible, lightweight PV, you need to understand how to work with fabric materials, so we worked with Base Structures.”
Base Structures has a 10-year pedigree in the fabric structures industry, “Probably number one in the U.K. in buildings,” Staplehurst says. “Base is doing a lot more in the building industry and is very good at making unique structures.” They understand the applicable building regulations.
“They were looking at us, and they said ‘you bring something completely new to this business,’” he says. “We realized that we’re addressing the building market and they’re addressing the building market; we can do something completely unique together.”
SCC soon discovered that there were “a huge number of market overlaps,” he says. “It got us thinking. We needed them for their capabilities and understanding of fabrics. They were looking at us as someone who could take them a step forward—lots of synergies on lots of levels: technical, resources, capabilities and deployment. Bringing the two together made good sense.”
SCC uses lightweight flexible TFPV modules, specializing in applying the modules through bonding, or fabric welding techniques, to the surface of the fabric or structure. The company concentrates on “CIGS” (copper indium gallium selenide) technology because it’s extremely lightweight and flexible. This makes it functional for structures with lightweight roofing—structures that can’t support any heavy weight, or may have constraints on penetration, or that aren’t square or flat.
“This brought up the point of working out a method to deploy solar roofing on this scale,” Staplehurst says, and the company looked more closely at canopies, particularly for carport systems. “This is where the nascent market is—in carport systems.”
Staplehurst says that the solar industry in the U.K. is paying more attention to fabric-based technologies, rather than steel or glass. Improved efficiencies have made it possible for flexible PV materials to compete on a larger scale, which also brings down the cost. “Most were deployed in specialty areas, like space or niche markets where you can command a high value,” he says. Now flexible technologies like CIGS are “starting to come into the commercial envelope,” he says, and they can deliver the power levels needed at a commercially viable price point.
“There’s a bit of a different dynamic in the industry now, too,” he adds. “The emphasis is on demand-side energy management rather than supply side (grid): your price point is significantly higher than grid price, but people are now starting to look at reducing their own energy requirements (dealing with consumer-level prices, not grid-level prices) and given that they’re looking at it as a long-term asset, you have a market,” he says.
“For example, a commercial building that consumes a lot of power is connected to the grid. So where can you generate electricity?” he asks. “Your parking. Now you can introduce solar power at a price point that’s competitive.” Branding for commercial clients is also important, and there is a growing pool of potential customers that want it not only for its practical value but also for its cachet.
“Lightweight solar is going to completely change how a company deploys the use of solar energy,” Staplehurst says. “We are a new kid on the block, but Base [Structures] has been around 10 years. It’s the combination that will differentiate us in the market.”
Janet Preus is senior editor of Advanced Textiles Source.