Transparent Panels Signal the Future of the Solar Industry

Imagine a world where every glass surface produces solar power. You'd wake up to the alarm on your fully-charged smartphone, pluck it off the windowsill and hop into a hot shower -- courtesy of a solar water heating system powered by your enclosed patio. You stroll out to your electric vehicle and flip on the radio, powered by your sun roof, and head off to your net-zero office building -- which skirts the grid thanks to its majestic floor-to-ceiling windows.

This scenario may sound like science fiction, but recent developments in solar technology suggest that it barely scratches the surface of where the industry may be headed in the coming decade. Earlier this week, German solar company Heliatek unveiled a 40 percent transparent organic solar cell that's ideal for generating energy from windows, façades and glass car roofs.

The development holds potentially groundbreaking implications for the new generation of net-zero smart buildings, as well as the alleviation of electric vehicle range anxiety. The possibilities are diverse, but it may be a while before we see transparent cells in use on a large scale. Heliatek has achieved 7 percent efficiency on its latest cell. This is respectable compared to its world-leading 12 percent efficiency for opaque organic cells but still a far cry from the 44.7 percent efficiency achieved by the top-performing standard photovoltaic (PV) cell -- made by fellow German manufacturer Fraunhofer.

Unlike standard solar cells, which are typically made from silicon, the production of Heliatek's organic film is based on small molecules (oligomers) developed and synthesized at its lab in Ulm, Germany. Oligomers are deposited at low temperatures in a roll-to-roll vacuum process, and their selective absorption of the solar spectrum targets different colors and transparency to convert sunlight into electricity. This may prove to be a breadwinning technology in the long-run, but for now higher costs keep it in the "niche" category.

While producing more efficient transparent cells, especially organic ones, may prove challenging, Dresden-based Heliatek sees promise in its latest development. The company has been open about its strategy to supply its transparent solar film to glass manufacturers for both building integration (BIPV) and car roofs. In a media release about this latest lab development, CEO Thibaud Le Séguillon went as far as to say that, "The transparency of our products is at the core of our market approach."

Le Séguillon isn't the only one who has this idea. Earlier this week, researchers from Singapore’s Nanyang Technological University debuted a new solar cell material that doubles as a touch screen for electronic devices, information kiosks and other displays. The integrated solar cell/touch screen concept parallels the emergence of building-integrated solar cells, as well as cells that can be incorporated into fabrics and other wearable or portable items.

In another attempt to bring a silicon-killer on the scene, the NTU cell is made from perovskite -- a relatively inexpensive mineral composed of calcium titanate (titanate is a salt composed of titanium and oxygen). But a group of MIT researchers took things one step further, devising a way to manipulate E. coli bacteria to create self-repairing solar cells. Inspired by natural materials such as bone, the researchers coaxed bacterial cells to produce biofilms that can incorporate nonliving materials, such as gold nanoparticles and quantum dots. The addition of inorganic nanoparticles, particularly gold, made the bacteria conductive to electricity. This potentially paves the way for self-repairing, and even self-assembling, solar cells and batteries.

"It shows that indeed you can make cells that talk to each other and they can change the composition of the material over time,” says Timothy Lu, an assistant professor of electrical engineering and biological engineering at MIT and the senior author of a paper describing the discovery in the March 23 issue of Nature Materials. “Ultimately, we hope to emulate how natural systems, like bone, form. No one tells bone what to do, but it generates a material in response to environmental signals.”

While none of these developments are likely to revolutionize the solar industry in the short-term, they pull back the veil and give us a peek at what is sure to be a promising future; a future that's likely inconceivable to us now. One thing is certain: The industry is already on the rise, with a 15 percent growth rate in the global solar PV market last year, and other savvy (though decidedly less sexy) developments in areas like smart energy storage are paving the way for what could be a whole new power source. There's no telling what the future holds, but we'll be watching.

Images courtesy of Heliatek GmbH

Based in Philadelphia, Mary Mazzoni is an editor at TriplePundit. She is also a freelance journalist who frequently writes about sustainability, corporate social responsibility and clean tech. Her work has appeared on the Huffington Post, Sustainable Brands, Earth911 and The Daily Meal. You can follow her on Twitter @mary_mazzoni.