You'll be able to kiss rooftop rack-mounted solar structures goodbye if The Dow Chemical Co. and Energy Conversion Devices Co. have anything to say about it. Both companies aim to soon begin rolling out shingles with solar cells built in.
The shingles install much like ordinary asphalt versions. Their onboard solar cells interconnect and typically wire into the inverter through a hole cut in the roof deck. The resulting system eliminates the need for a separate framework to hold the solar array.
The shingles from Energy Conversion Devices are called PowerShingle and are sold through a subsidiary called Uni-Solar. The cells themselves are ECD's amorphous silicon technology which employs a triple-junction design that makes it about 25% more efficient than crystalline modules. The amorphous silicon sits on a flexible stainless-steel substrate. The finished product is flexible and can be installed on surfaces that may be curved to some degree.
The Dow product is called the Powerhouse Solar Shingle. It uses CIGS (copper indium gallium (di)selenide) photovoltaic thin-film cells in a proprietary shingle design. The cells come from Global Solar Energy Inc., Tucson, Ariz.
Dow says the cells operate at higher than 10% efficiency, which puts them below the efficiencies for the best crystalline cells, but claims the shingles would still cost 10 to 15% less on a per watt basis. This, in turn, should make the Dow Shingle about 30 to 40% cheaper than other building-integrated photovoltaic systems.
The Dow Chemical Co., http://www.dowsolar.com/innovation/protects.htm
Energy Conversion Devices Uni-Solar, http://www.uni-solar.com/
Global Solar Energy Inc., http://www.globalsolar.com/index.php