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Friday, July 07, 2006 Beyond the Solar PanelThe U.S. government plans to produce a buyer's guide to power-converting roofing materials. By Lamont Wood
The government tests cars for gas mileage. Now it's testing roof tiles for wattage. Homeowners have long been able to partially power their homes with sunlight, but it meant clumsily mounting photovoltaic (PV) panels on the roof. Now the latest generation of PV panels look and act much like ordinary roofing tiles or shingles. And the National Institute of Standards and Technology (NIST) is evaluating nine of these commercial PV roofing products in hopes of providing an easy way for consumers to judge the panels' power potential. "A lot of people are considering the use of PV products on their homes and businesses, and in order to make decisions on whether it's a worthwhile investment you need to predict their performance," says Hunter Fanney, head of NIST's Heat Transfer and Alternative Energy Systems Group in Gaithersburg, MD. "We are collecting detailed performance data to validate those models." The roofing materials, which use various types of solar-to-electricity conversion, are being tested for 15 months. Fanney hopes to use the data to build a computer program and database with, among other things, average flat-surface solar radiation readings for neighborhoods across the United States (as measured by the weather service at the nearest airport). Punch in the performance characteristics of the roofing product you want to use, plus your location, roof orientation and slope, and other data, and -- bingo -- you'll know what kind of wattage you can expect from your roof. According to Fanney, roofing tiles and shingles with embedded solar converters have been on the market for about three years. They look like regular roofing materials, keep out the sun and rain, and can be installed in much the same way. But by generating electricity, these tiles and shingles save consumers money. Around 500 square feet of PV tiles can produce three kilowatts of electricity, according to Subhendu Guha, president and chief operating officer of United Solar Ovonic, a maker of PV shingles in Auburn Hills, MI -- and most roofs are several times that size. His company's version is dark blue and can blend with ordinary shingles of a similar shade. Or a builder might devote an entire sunny section to PV materials. "A south-facing roof on a three-bedroom home could supply 20 to 30 percent of the home's electrical needs," says Paul Maycock, a consultant and head of PV Energy Systems in Williamsburg, VA.
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Toward Cheaper, Robust Solar Cells
03/13/2008
Massachusetts Institute of Technology
Comments
Guest (mike) on 07/07/2006 at 12:00 AM
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Guest (josh wood) on 07/14/2006 at 12:00 AM
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hiofarwa on 10/29/2006 at 9:33 AM
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do you live in a very sunny place then choose mono-crystalline solar modules. when you have a lot of diffuse light, then use poly-crystalline solar modules.
Guest (Marco) on 07/10/2006 at 12:00 AM
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Guest (alfranco) on 07/10/2006 at 12:00 AM
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Brian Dougherty (sent 7/1) questioning the validity of this siting.
As for PV, it's like your windshield it works best if periodically washed and cleaned. No problemo.
Guest (John) on 07/12/2006 at 12:00 AM
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Guest (Mike) on 07/12/2006 at 12:00 AM
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http://www.bfrl.nist.gov/863/bipv/roof.htm
The residential test section appears to be sloped.
Guest (John) on 07/12/2006 at 12:00 AM
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Japan?? Also, I understand the top surface may be a fluoropolymer film, maybe that would help to reduce adhesion of city grime? Or perchance create a new industry (chimney sweeps to roofing sweeps)?
Guest (Leon Viveros) on 07/15/2006 at 12:00 AM
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Guest (Mike) on 08/07/2006 at 12:00 AM
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swing2glory@hotmail.com on 03/13/2007 at 12:27 PM
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Guest (Em) on 07/20/2006 at 12:00 AM
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As for slope: for best results you want to have the sun light coming perpendicular to your panels. Sloped roofs work better than flat roofs (get more light).
And this changes with latitude.
If builders start including this in their desings, house orientation and roof shapes and slopes will be designe for the local condition to optimally make use of the sun in each particular location.
Guest (Ron) on 07/24/2006 at 12:00 AM
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site is www.openenergycorp.com . There is some other interesting things there as well.
Guest (arnold) on 08/03/2006 at 12:00 AM
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hiofarwa on 10/29/2006 at 9:26 AM
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PV solarpanels are good to use anywhere, don't understand me wrong. even in canada or norway. i live in the netherlands where we have very diffuse light now and then, but no problem for solar, using poly-crystalline solar modules. these are perfect for that kind of conditions.
a rule of thumb is; the hotter (not about light) a climate is the better you should use thermal-electro solar power, since PV panels don't like their working surface very (VERY) hot. at the end, its all about efficiency and how much you want to matter with that, because we are talking about percents power more or less... writing this, i think i wouldn't care about it too much. just put the panels there and shout it out! so that others hear it and do the same!
tobiasonp on 10/27/2006 at 3:26 AM
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It would be helpful to know the full expense plus all the maintenance needs and failure rates. Also, in the tropics (like Guam), air conditioning is the real energy hog. A solar system for this might be unaffordable for most people. And then there are the typhoons....
hiofarwa on 10/29/2006 at 9:11 AM
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wbiggs2 on 11/13/2006 at 12:28 PM
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hiofarwa on 10/29/2006 at 9:36 AM
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solar jon on 04/12/2007 at 4:17 PM
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