The Secretary of Energy, Steven Chu, suggested reducing energy consumption in the USA by 10-15% simply by painting the roofs of houses white. What if that currently unused space was used to generate energy instead? Used are wind turbines (though many residential restrictions on sound and height stymie development for most areas), conventional PV panels, and solar shingles.
Solar shingles are designed to look and behave like traditional roof shingles; stepped on, nailed down, and looking like normal shingles. The added benefit, of course, is they generate clean electricity on previously wasted space. Dow Chemical Company is betting on shingles, estimating a $5 billion market by 2015 and $10 billion by 2020. This optimism is being carried by the Solar Solutions unit of Dow and the company will soon begin testing their shingles on new homes with the help of a $17.8 million tax credit from the U.S. Department of Energy. The shingles plug into each other and are nailed like normal asphalt shingles and have plastic coverings, letting them be walked on and installed by a roofer in half the time compared to conventional mounted PV; an electrician is still needed for the inverter to connect to the grid. Dow partnered with Global Solar Energy and made cells of copper, indium, gallium and selenium (Cigs) instead of amorphous silicon. Specifications are not yet revealed for the Dow Powerhouse system, but early data claims they are 13% efficient compared to 11% for previous thin-films. Dow claims that the system is 15% cheaper than rack mounted PV and 40% cheaper than other solar shingles, estimating that a 1,000 square foot roof of solar shingles costs $10,000 – not cheap, costing about twice as much as asphalt roofs – and generate 3.5 kW of power – maximum sun and ideal condition, not offsetting entire home electric use.
Would it be better to install the solar shingles or simply paint the roof white? It’s certainly cheaper in capital costs. However, Dow estimates that with government subsidies the system will pay for itself in 10 years. Will it last that long? Dow is testing the system, the plastic coverings help, and aiming to provide a 25 year warranty – same offered by most asphalt shingles. Painting a roof white has immediate economic benefits but the answer from most neighborhood associations is no. Aesthetics currently trump the environment. The only option for most homeowners to reduce grid use is solar systems and Dow’s new Powerhouse solar shingles provides an enticing option. They should be on the market by 2011 for those willing to try something new.
 Technology Review – http://www.technologyreview.com/business/24383/page2/