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Solar Thermal Energy. Parabolic Trough. The largest ‘solar thermal-electric’ installation of its kind in the world, the Luz project in California’s Mojave Desert, has a peak output of some 350 megawatts and occupies several square kilometers of land . Solar Power Tower.
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Parabolic Trough The largest ‘solar thermal-electric’ installation of its kind in the world, the Luz project in California’s Mojave Desert, has a peak output of some 350 megawatts and occupies several square kilometers of land
Solar Power Tower In 1995 Solar One was converted into Solar Two, by adding a second ring of 108 larger 95 m² (1,000 ft²) heliostats around the existing Solar One, totaling 1926 heliostats with a total area of 82,750 m² (891,000 ft²)
Solar Dish Stirling Energy Systems‘ solar dish technology is the world’s most efficient device for the conversion of solar energy to grid-delivered electricity, nearly twice as efficient as any alternative solar technology.
Plant Locations • Direct normal solar radiation • Land Ownership • Road Access • Local transmission infrastructure capabilities and loadings • State-level policies and regulations
Economic and Environmental Benefits • Creation of jobs for both construction and operation • Increase in state and local tax revenues • Increase in gross state output
Market Development • The Southwest CSP has set a goal of achieving 1,000 MW of CSP systems in the southwestern US by 2010. • US DOE’s goal is to develop 30,000 MW of new clean and diversified generation by 2015. • SolarPaces plans to deploy 5,000 MW of CSP by 2015.
Residential Applications • Solar Heating • Solar Cooling • Solar Hot Water • Solar Lighting
Types of Solar Water Heating Systems • Flat-plate collector • Glazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic covers. Unglazed flat-plate collectors; typically used for solar pool heating, have a dark absorber plate, made of metal or plastic, without a cover or enclosure. • Integral collector-storage systems • Also known as ICS or batch systems, they feature one or more black tanks or tubes in an insulated, glazed box. Cold water first passes through the solar collector, which preheats the water. The water then continues on to the conventional backup water heater, providing a reliable source of hot water. In cold winter climates these systems must be drained to avoid freezing. • Evacuated-tube solar collectors • They feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin's coating absorbs solar energy but inhibits radiative heat loss. These collectors are used more frequently for U.S. commercial applications.
Active solar water heating systems • Direct circulation systems • Pumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes. • Indirect circulation systems • Pumps circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures.
Passive solar water heating systems • Integral collector-storage passive systems • These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs. • Thermosyphon systems • Water flows through the system when warm water rises as cooler water sinks. The collector must be installed below the storage tank so that warm water will rise into the tank. These systems are reliable, but contractors must pay careful attention to the roof design because of the heavy storage tank. They are usually more expensive than integral collector-storage passive systems.
Comparison • Passive solar water heating systems are typically less expensive than active systems, but they're usually not as efficient. However, passive systems can be more reliable and may last longer.
Passive solar home • Passive solar homes range from those heated almost entirely by the sun to those with south-facing windows that provide some fraction of the heating load. The difference between a passive solar home and a conventional home is design. The key is designing a passive solar home to best take advantage of your local climate. For more information, see how a passive solar home design works.
Solar Collector • Solar Thermal is a clean, highly efficient means of using renewable energy from the sun to provide hot water for domestic, commercial and industrial process . Put in simple terms, if you place a container full of liquid in the garden on a sunny day, in a short time the contents of the container become warm. Solar Collectors work in much the same way, but are very more efficient.
A sealed circuit of fluid containing a special mix of glycol and water is pumped around the system through the Solar panels where it is heated and passed through a special solar coil within the hot water tank. The heat is then transferred to the main body of water within the tank, once up to temperature, this water is ready for use in the house, office or factory.
Passive Solar • Passive Solar is accommodated in the design of some homes where living rooms are south facing with large windows and floors and sometimes walls have a large thermal mass. • While it is necessary to use the solar to heat in winter overheating in summer has to be avoided, this is normally done by having a roof overhang which blocks the high summer sun but not the low winter sun. • While it can provide some free heat it doesn’t supply hot water and there are design constraints.
Principle of an evacuated tube collector with heat pipe; view from top
A double-cycle system with forced circulation with a conventional boiler for back-up heating
Collector efficiencies at different irradiances and temperature differences
Solar Collector Markets • China is by far the world’s largest manufacturer and user of solar water heating. • By the end of 2002, the total installed area of solar domestic hot water systems there was about 40 million m²; annual production and sales volume reached about 8 million m² in 2002. • There are now more than 1000 manufacturers producing and selling solar thermal systems, and a total turnover of more than €1 billion has been achieved. • Evacuated-tube collectors dominate the Chinese domestic and export markets. • Elsewhere, about 1 million m² of collector surface was installed in the US by 2001; almost all of this was made up of unglazed absorbers used for swimming pool heating.
Solar Collector Markets • In Europe, there was about 1.1 million m² of collector area installed by 2002, and the flat-plate collector dominates installations. • About half of these installations have been realized in Germany. • The solar collector market mainly depends on political conditions in a particular country, and in Germany, for instance, the collector market dropped by 40% in 2002 due to uncertain political conditions, though it recovered again in 2003. • However, the EU has very ambitious targets for collector installations, with a target of 100 million m² by 2010. • Solar thermal systems will then play an important role in the struggle against global warming.
Hybrid solar technology • Developed at Oak Ridge National Laboratory, the hybrid solar technology uses a rooftop-mounted 48-inch diameter collector and secondary mirror that track the sun throughout the day using GPS. • The collector system focuses the sunlight into 127 optical fibers connected to special light fixtures equipped with diffusion rods similar to fluorescent light bulbs. • The rods spread light in all directions.
Hybrid solar technology • Hybrid solar lighting systems are being tested in various demonstration projects around the country including a Wal-Mart in McKinney, Texas, a Staples store in Long Island, N.Y., a Braden’s Furniture showroom in Knoxville, Tenn., the Naval Exchange in Hawaii, some office space at San Diego State University, the Aveda corporate headquarters in Minneapolis and Oak Ridge National Lab’s Multi-Purpose Research Facility.
