Facing the Right Direction
A southern partnership promotes solar energy
The attractive array of solar cells purchased from Arizona Public Services injects electrical power into the local distribution system, subtracting around 9000 kilowatt hours from ORNL's annual electric bill.
The device was dedicated Oct. 24, 2007, at the opening of the first Southeast Solar Summit, held at ORNL's new conference center. Sharp Electronics Corp. of Memphis, Tenn., manufactured the photovoltaic modules in the array.
On the roof of the largest research building along the courtyard perches a 700-watt solar system designed by JX Crystals. The combination of concentrating solar modules and a turntable tracker makes the photovoltaic system more efficient and less costly than conventional systems. In each module 24 reflectors focus sunlight onto 72 single-crystal silicon solar cells. The four 175-watt modules concentrate sunlight up to three times its normal strength, reducing by two-thirds the number of expensive silicon cells required to produce the same amount of electricity.
An inexpensive solar tracker keeps the modules facing the sun throughout the day, theoretically increasing the energy output as much as 35% in some regions. ORNL purchased and installed the system in September 2007. Data from the electrical performance and efficiency tests were jointly presented by ORNL's Curt Maxey and JX Crystals at a recent international conference in Germany.
The rooms at the top of a nearby four-story research building are illuminated by hybrid solar lighting. In this technology pioneered by ORNL, sunlight is piped into rooms through optical fibers, and intelligent sensors adjust artificial light levels needed by occupants during cloudy days. Sunlight Direct of Oak Ridge is commercializing this technology, which has entered the demonstration phase with installed systems at locations owned by Wal-Mart, Staples, Battelle and San Diego State University.
ORNL materials researchers using the plasma arc lamp hope to demonstrate elimination of defects from multicrystalline and amorphous silicon thin-film solar cells, which are less efficient than single-crystal solar cells but less expensive to make. Measurements of these processed materials will be made at the new Center for Advanced Thin-film Solar Cells. (See Research Horizons: A Renewed Interest)
The Department of Energy, not surprisingly, is a major driver behind ORNL's expanded research in solar energy. Craig Cornelius, acting program manager of Solar Energy Technologies in DOE's Office of Energy Efficiency and Renewable Energy, has indicated that greater funding for research to make solar materials more efficient and less expensive will be available to national laboratories.
Indeed, the fiscal-year 2008 budget recently enacted by Congress contained one of the largest funding increases in history for alternative energy research. ORNL, which boasts one of the world's leading materials research capabilities, proposes innovative basic technology research to help meet DOE solar materials challenges.
The Department of Energy has mandated that by 2013 7.5% of all energy used at national laboratories must be produced from renewable energy. ORNL plans to install more photovoltaic panels, perhaps as solar walkways and solar roofs over parking lots, and possibly biomassfired boilers, to help achieve that goal.
Cornelius, who leads the Solar America Initiative as part of the President's Advanced Energy Initiative, has stated that DOE's goal is to make solar energy cost-competitive with conventional forms of electricity by 2015. DOE predicts that by 2015, solar energy will produce 15 gigawatts, enough to power 11.2 million American homes.
"Adding solar energy to our nation's energy mix will increase America's energy security by providing decentralized sources of clean power for the electric grid," he said. "Solar power will improve the environment by avoiding 191,000 tons per year of carbon dioxide emissions and boost the economy by promoting a U.S.-based solar industry."
Curt Maxey with concentrating solar modules.
The Tennessee Valley Authority is also pushing solar energy. Through a collaboration with ORNL, TVA recognizes that wide deployment of solar energy could help solve the peak power problem that threatens the grid's capacity during the hottest days of summer. In his talk at the summit, ORNL's Jeff Christian reported that, on the hottest day of 2007 in East Tennessee, he actually took a near-zero-energy house in nearby Lenoir City off the TVA grid. Meanwhile, the residents remained comfortable in the house with rooftop solar panels and energy storage in the basement. His experiment suggested that peak demand-and the expensive capacity needed to meet that demand-can be reduced if enough solar zero-energy households could do without grid power between 5 and 7 p.m. daily in summer when demand for power for air conditioning normally soars.
One challenge is to convince American consumers to purchase and install solar technologies. A recent survey of 500 individuals indicated that consumers tend to associate "green" with "more expensive" and are skeptical about corporations that they suspect are more interested in selling products than solving environmental problems. Tennessee Governor Phil Bredesen has encouraged the growth of a solar energy industry in the state through clean energy grants. For the time being, the relatively low cost of TVA electricity is a disincentive for homeowners to make the transition to solar technology.
Germany is the fastest growing market for photovoltaic cells because the government pays a premium price for electricity from solar panels. In the Southeast, the average amount of sunlight available for producing electricity is twice that available in Germany. To boost U.S. solar capacity (which is responsible for one-eighth of 1% of U.S. electricity generation), other barriers must be overcome in addition to increasing efficiency and reducing cost. At the summit, attendees noted the need for a national net metering standard, more certified installers of solar panels and ways to dissipate the heat generated by concentration of sunlight on roofmounted panels.
Many baby boomers about to retire have expressed strong interest in moving to "Deep Green" communities. One such planned community is Walden Reserve, which will be located on 6,000 acres of heavily forested ridges between Black Mountain State Park and Ozone Falls State Park, only 40 miles from Oak Ridge. Because houses will be surrounded with trees, the roofs will not have solar panels. However, a photovoltaic system is planned for an open field to help provide electricity to the self-contained community, which will have its own energy sources, water supplies and sewer system.
Walden Reserve is envisioned eventually to accommodate 20,000 residents and provide them with restaurants, a golf course, a spa, greenways for hiking and biking and other community amenities. The development of Walden Reserve is guided by 12 "bedrock principles" to ensure environmental responsibility. Developers hope the community will act as a testbed for "green" products and services.
"Projections call for more new home and building construction in the Southeast than in any other region," says Patrick Hughes, manager of ORNL's Building Technologies Program. "Our region has the opportunity to lead because volume begets affordability. Imagine if Walden Reserve succeeds in developing an entire all-electric community that contributes zero to TVA's peak period loads."
Hughes said one outcome of the summit was the recognition of the importance of policy and leadership. Germany leads the world as a market for solar cells for these reasons, even with a solar resource eclipsed by Tennessee's.
"The most exciting outcome of the summit for me was the evidence of some emerging leadership," he continues. "With the leadership from DOE, the state of Tennessee and TVA, people in this region can create remarkable communities of ultrahigh-efficiency, demand-responsive buildings powered in large part by solar and other forms of renewable energy."
Facing the sun may be the first step in the right direction.