 to carry water that will cool the other layers while also carrying away heated water, and a bottom layer of reinforcing plastic.){kind=spacer}
HYBRID SOLAR PANEL DIAGRAM The hybrid solar panel that Yin designed has as its outermost layer a clear protective cover, followed by a layer of thermoelectric material, a layer with plastic tubes (called the functionally graded material interlayer) to carry water that will cool the other layers while also carrying away heated water, and a bottom layer of reinforcing plastic.
Image: © COLUMBIA UNIVERSITY
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Tar and shingles are hardly environmentally friendly materials, so the U.S. Department of Energy (DOE) hopes to soon help homeowners and businesses replace the roofs over their heads with something greener. To that end, the DOE awarded Weidlinger Associates, a New York City-based structural engineering firm, a $150,000 grant earlier this month (matched by a 10-percent commitment from the state) to develop durable hybrid solar roofing panels with integrated photovoltaic cells and thermoelectric materials that harvest the sun's energy to produce both electricity and hot water for buildings.
Weidlinger is working with Columbia University in New York City on the project, which the engineers and researchers hope will convert at least 12 percent of collected sunlight into electricity. This would be an improvement over the 5- to 10-percent conversion rate possible with relatively inexpensive thin-film plastic solar cells, although a far cry from the most complex (and expensive) solar cells, which have achieved a conversion rate as high as 41.6 percent.
These new photovoltaic thermal hybrid panels presently exist only as prototypes. Beneath the clear, outermost protective cover is a layer of photovoltaic cells, followed by a layer of thermoelectric material, a layer with plastic tubes (called the functionally graded material interlayer) to carry water that will cool the other layers while also carrying away heated water, and a bottom layer of reinforcing plastic. The photovoltaic cells convert the sun's electromagnetic radiation into electricity, while the thermoelectric layer converts the sun's heat into electricity.
The water tubes are crucial to the design. Typically, when photovoltaics heat up they begin to lose their efficiency at normal operating temperatures in a sunny environment, says Greg Kelly, Weidlinger's director of sustainable design. The design created by Huiming Yin, an assistant professor of civil engineering and engineering mechanics at Columbia, incorporates a capacity to cool down the photovoltaics while also heating water for use in the building to which the panels are attached.
In addition to being tested in Columbia's lab, a number of these panels will be installed atop a 6.4-square meter shelter located on the roof of the Frederick Douglass Academy, a New York City high school that specializes in the education of disadvantaged and underrepresented educational groups. Once the shelter is built, students will monitor the performance of the panels. "What we have to do is demonstrate a general commercial viability," Yin says, adding that this means getting both the technology and its associated costs just right. The researchers have yet to calculate the cost of the technology per watt, a standard measuring stick to determine whether a renewable energy project can compete with established fossil-fuel technologies.
If this phase of the project is successful, the work done by Columbia and Weidlinger could move to a second phase within six months. That second phase is likely to offer the researchers $1 million in DOE funds for a year to further develop the technology, Kelly says, whereas a third phase would likely involve as much as $10 million to prepare the technology for production. "We're looking at a five-year process to come to market, assuming all goes well," he adds.
The DOE is behind the technology thus far. "Solar panels have not achieved market penetration due to high initial costs and inefficiency, but the hybrid building-integrated panels from this project will be part of the building's skin and significantly more efficient," according to a DOE statement e-mailed to Scientific American. "These less costly and more durable panels are suitable for residential and commercial projects for new construction and renovations."
The broad concept of building a solar panel that is tough enough to act as a roof panel yet sensitive enough to capture as much of the sun's energy as possible is likely feasible, says David Ginger, an associate professor of chemistry at the University of Washington in Seattle. "Of course, putting all these ideas into the same package in a cost-effective manner is often more challenging than pitching the idea on paper, which is why you want clever engineers trying out new designs and then testing them in real-world environments," he adds.
And although this idea of "building-integrated photovoltaics" (BIPV) is not new, the Columbia-Weidlinger multilayered hybrid design is different from anything currently available to builders. SolarWorld AG in Germany, for example, sells a technology it calls Energyroof, which consists of panels covered with solar laminates that generate electricity but does not include a layer of thermoelectric material.
In October, The Dow Chemical Company announced its Powerhouse Solar Shingle, which the company says can be integrated into rooftops with standard asphalt shingle materials. These solar shingles, which feature thin-film copper indium gallium selenide (CIGS) photovoltaic cells, are expected to be available in limited quantities by mid-2010 and projected to be more widely available in 2011. In 2007, the DOE had given Dow $20 million in funding to develop building-integrated solar arrays for the residential and commercial markets.
Once Weidlinger and Columbia create their panels, the engineers will have to decide how best to keep them waterproof and resistant to fire, Kelly says, adding, "We also want to get parity with the weight of existing roofing systems."
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13 Comments
Add CommentNext - cover the roof of every home and building in the US with this type of product.
Reply | Report Abuse | Link to thisI could not agree more, with candide. Time is running out. This and other solar technologies are crucial to our survival. And speed IS of the essence.
Reply | Report Abuse | Link to thisYou bettya! Then the electric companies will bill you for *not* delivering electricity.
Reply | Report Abuse | Link to thisSee: Colorado
It's the "line fee" that'll be even higher when they're *not* generating real electricity. We cannot win this war. We have no lobbyists.
Nothing will be more expensive than FREE electricity! Watch, you'll see.
While if done cheap could be worth it, CSP solar is far more eff at 25-30% for electric and has higher quality heat for space heating or hot water. Cost in mass production under $3k/kw and can be fired by most any bio or other fuel if power, heat needed and the sun don't shine.
Reply | Report Abuse | Link to thisWhy does the government need to be involved? There's is no "invention" reported here. When the costs of conventional electricity rise to the level of solar then the free market will provide the answer. We dont need the government trying to pick winners and losers. They have too few minds compared to the free market.
Reply | Report Abuse | Link to thisWhen private enterprise bets with their own money you will see results, not the government betting with other people's money.
Question: Is a solar panel in the sun hotter, and/or less black (other than in infrared) when it's not connected to produce electric power?
Reply | Report Abuse | Link to thisThe idea of water-cooled solar panels has been around for years, Why didn't it take hold? This sounds like a good improvement.
Daniel35:
Reply | Report Abuse | Link to this"Question: Is a solar panel in the sun hotter, and/or less black when it's not connected to produce electric power?"
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PV panels being of dark colors (mine are dark blue) always get hotter and less efficient in the sun, even in winter, regardless of being electrically connected or not.
This is a good idea that needs more experimentation.
Roofing with used PC motherboards may be another alternative to bitumen. When CMOS versions of cloud computing may mature to the PC, lots of wasted power to run CPU's will be saved, The demand for unwanted motherboards may then hopefully, be reduced by the availability of full solar spectra panels similar to the prototype discussed.
Reply | Report Abuse | Link to thisDON'T CONFOUND HOT WATER AND THERMOELECTRICITY!!!
Reply | Report Abuse | Link to thisI am embarrassed that my home state of Arizona doesn't have technology like this wide spread. The fact that we spend one penny or burn any energy at all here 8 months out of the year to heat water is a crime.
Reply | Report Abuse | Link to thisray, why not 12 months out of the year for producing hot water instead of 8 months in the desert southwest? Actually, the newer evacuated-tube technology produces good hot water in colder climates even on cloudy days. It's actually a crime we don't use that technology all over the country, since domestic hot water is one of the largest household uses of energy!
Reply | Report Abuse | Link to thisA lot of stuff did not take when it should have. We've been addicted to oil for way too long, and they made it cheap enough, we never bothered to seek alternatives in earnest...until our $150 a barrel oil scare in 2007-08.
Reply | Report Abuse | Link to thisEven that one will wear off if you do not stay focused this time. The consumer basically follows the buck, and the advertising. Maybe this time, the message of going greener is getting across.
I'm glad there are more companies out there offering roof-sets for hot water and electricity, and not just in CA any longer. The consciousness is slowly opening up. As these new go green companies expand, it will create jobs.
That is why you get enough panels and batteries so that you don't need to be on-grid in the first place.
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