Solar tile

Solar tiles may be blue or black.

Until recently, if you wanted a home solar-power system, you had to install a set of large photovoltaic panels on the roof or in the yard. But nowadays you have more choices, including low-profile solar tiles that can be integrated with standard siding or shingles. While solar tiles are a clear aesthetic improvement, they're a new technology that's still very much under development; they will continue to become more viable with every year's advances, but currently they may only be practical for some homeowners.

History

Solar tiles have been in use since the 1990s. In 1996, photovoltaic shingles won "Popular Science" magazine's Grand Award for the best new technology. Since then, they've continued to gain popularity among green builders, and are most commonly used in place of or in conjunction with standard roof tiles or shingles. In 2007, the U.S. Department of Energy reported that California developers planned to install hundreds of solar tile arrays in new homes  continues, however, into improving the tiles' energy efficiency and cost.

Design and Materials

Solar tiles can be made of silicon, like traditional solar panels, or they can incorporate non-silicon materials like cadmium telluride. Photosensitive materials can be applied in an extremely thin layer --- a film that is only a few micrometers thick --- which allows thin-film solar cells to be formed to any shape, including shingles and roof tiles. New third-generation solar cells are under development in 2011, using a variety of new materials and manufacturing techniques. It's likely that third-generation cells will be more cost-effective and have higher energy efficiency than second-generation models, as well as being adaptable to a wider range of uses. 

Efficiency

Traditionally, solar tiles have had significantly lower energy efficiency than traditional solar panels. They simply haven't been shown to produce as much energy, and this is partly why they are less commonly used. In 2008, however, U.S. Department of Energy researchers created a thin-film solar cell made of copper indium gallium diselenide (CIGS) with 19.9 percent efficiency. Traditional solar panels have a maximum efficiency of around 20 percent. This new development in thin-film efficiency may make solar tiles a more viable option for builders and homeowners. 

Cost

Solar tiles can be costly: They cost more to produce, and require more time to install, than traditional solar arrays. A 2001 study found that solar tiles cost more per watt than traditional panels. That cost gap may be disappearing, however. In 2009, Dow Chemical Company announced that it would begin manufacturing a new type of solar shingle that costs 10 to 15 percent less per watt than standard solar cells. These new shingles can be installed in about 10 hours, a considerable improvement over older shingles. This cuts back on installation costs, making solar tiles a potentially cost-effective choice.