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Meanwhile, humanity struggles with the effects of pollution, climate change and fossil fuel dependence. Could it be that the solution to these problems is right above us? Modern photovoltaic (PV) technologies take advantage of renewable energy from the sun by converting sunlight into electricity. So why aren’t more of us using this remarkable technology to power our homes? When asked, the reason most people give is the cost of installing a PV system. But new thin-film PV products are getting better and cheaper all the time. This technology could soon change the way we think about electricity and make sunshine our “fuel” of choice.

The Rise of Thin-film Solar

The type of solar-electric module currently dominating the industry is crystalline silicon, which is made by encapsulating wafers of highly refined silicon under rectangular sheets of glass framed with aluminum. These modules have been the primary solar energy technology for more than 50 years. Crystalline modules still dominate in PV sales, but in the last few years most new development work has focused on thin-film PV technologies. In 2005, more than 95 percent of the PV market was served by crystalline modules. Since then, thin film’s share of the market has risen steadily and is now 25 percent. Hundreds of thinfilm companies have entered various stages of product

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development or production. Large-area thin-film PV modules and laminates have been commercially available since the ’90s. Thin-film modules still aren’t as efficient per unit area as crystalline silicon modules, however, they have other advantages over crystalline silicon. Perhaps most importantly, thin-film solar is much less expensive to produce. Many thin-film panels are produced from amorphous silicon. These solar cells require much less high-grade silicon than it takes to produce crystalline silicon panels. Thin-film solar cells can also be made from other semiconductor materials, including copper indium gallium diselenide (CIGS) and cadmium telluride.

Can We Make Every Roof a Solar Roof?

Rather than building massive new power plants, why not install PV panels on every sunny roof and on simple shade structures over every parking lot? The same mass adoption that allowed room-sized mainframe computers to morph into laptops could cause huge, centralized power plants to give way to rooftop PV panels. In fact, some U.S. policies already encourage distributed generation by giving substantial tax incentives to homeowners and businesses that install PV systems. Because thin-film solar panels are both lightweight and flexible, it’s possible to incorporate them directly into buildings — as roofing materials, for example. The idea of building-integrated photovoltaics is not new. Architects have been using PV modules as roofing since the early ’80s, but using the glass modules available at that time was both challenging and expensive. Glass is transparent, longlasting and weatherproof, but it can shatter and is not an ideal roofing material. In contrast, thin-film solar cells work very well on rooftops. Uni-Solar’s amorphous silicon thin-film laminates have been available for more than a decade, and new solar roofing products may soon be coming on the market. In October 2009, CertainTeed, a leading North American manufacturer of asphalt shingles, announced an agreement

A Practial Journal for Friends of the Environment c GreenLivingJournal.com d Summer 2010

Green Living Journal Summer 2010 # 9  

"A Practical Journal for Friends of the Environment" Articles: Power Plants of the Future, Recycling Books, Locavore Basics, Clean Diesel, E...

Green Living Journal Summer 2010 # 9  

"A Practical Journal for Friends of the Environment" Articles: Power Plants of the Future, Recycling Books, Locavore Basics, Clean Diesel, E...

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