Dow’s Solar Shingles

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.

Dow's 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.

Installing the shingles is easy.

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.

Sources:

[1] Dow – http://news.dow.com/dow_news/corporate/2009/20091005b.htm

[2] Engadget – http://www.engadget.com/2009/10/08/dows-powerhouse-solar-shingles-get-along-with-non-solar-sibling/

[3] Impact Lab – http://www.impactlab.com/2010/01/20/dow-chemicals-solar-panel-roof-shingles/

[4] Technology Review – http://www.technologyreview.com/business/24383/page2/

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One response to “Dow’s Solar Shingles

  1. I was concerned about the paint used to paint roof’s white: does it have run off contaminates, would you have to re apply it annually, etc? But after reading about the Hyperglass Cool top paint it is an “eco friendly product” that does is a non-solvent, non-toxic, elastomeric coating that is specially formulated with high quality glass microspheres. The infusion of microspheres nearly doubles the reflective properties, as well as making the coating extremely durable, water resistant, and lighter than regular paints [1]. There are other products that require annual reapplications but this product didn’t seem to need any after 2 coats of paint on roof. The white paint can be added directly on the current asphalt shingles or other surface tops instead of just smooth surfaces. This also reduces the heat island effect.
    As for the shingle solar roofs, I think they have a lot of potential. You mentioned that these take half the time to install than other rack mounted PV systems, and are just nailed in like regular asphalt shingles. I think that this could create a competitive market to already existing solar installation companies, because now asphalt roofing companies don’t need any new labor skills except a electrical is required for the hook up. Since about 80% of the roofs in the U.S. are asphalt [2], there is an already existing infrastructure for installation. I would be curious once this product comes online in 2011 what exactly there specifications are.
    I am curious if all things considered for comparing shingles vs white roofs carbon foot print; including manufacturing, transportation, and mining of resources used, how much emission saved from generating electricity for solar, which would be environmentally better and cost efficient and money savings. According to a published article in the journal Climatic Change [4], Akbari, Menon and Rosenfeld have calculated the CO2 offset, or equivalent reduction in CO2 emission, achieved by increasing the solar reflectance of urban surface that so retrofitting 100 meters^2, (1000 square feet) of roof offsets 10 tones of CO2 emission, (for comparison purposes, a typical US house emits about 10 tones of CO2 per year)
    For now, $500 vs $10,000 for 1,000 square feet on a roof can make a large impact on carbon emissions whether for electricity form solar shingles or white roofs. Could we see future laws that require white roofs, green roofs, or solar panels? In California white roofs are required on all flat roof tops [5]. Hopefully Austin will see something like this soon.

    References:
    [1] http://store.hypersealinc.com/ProductDetails.asp?ProductCode=TopCoat01

    [2] http://homerenovations.about.com/od/houseexteriorframeworkaHowToPaintRoof.htm
    [3] http://www.energy.ca.gov/2008publications/CEC-999-2008-031/CEC-999-2008-031.PDF

    [4] Akbari, H., S. Menon, and A. Rosenfeld. 2008. “Global cooling: increasing solar reflectance of urban areas to offset
    CO2,” In press, Climatic Change. Hashem Akbari is a senior scientist (email H_Akbari@lbl.gov, phone +1-510-486-4287)
    and Surabi Menon (email SMenon@lbl.gov , phone +1-510-486-6752) is a staff scientist with the Lawrence Berkeley
    National Laboratory. Arthur Rosenfeld is a commissioner with the California Energy Commission (email
    Arosenfe@energy.state.ca.us, phone +1-916-654-4930)

    [5] http://www.greenrightnow.com/kabc/2009/04/06/cool-your-roof-with-white-to-save-money-and-the-environment/

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