- Email: [email protected]
Efficient power inverters
NEWS warrant the capital expenditures that would allow them to continue running. A few municipal utilities in Burbank, Pasadena and Los Angeles are looking at replacing old units with new and more efficient generation. AES Corporation, Reliant Resources and NRG Energy own the remainder of the generation affected by California Rule 2009, and are evaluating options on whether to improve or shut down the units.
Transparent collectors Conventional solar heat collectors are manufactured with coated sheet metal and hard glass (few are from plastic with metal). This is a labour-intensive construction, expensive and physically heavy, as well as being difficult to recycle and always darkly opaque. An Austrian entrepreneur has now developed a new solar collector, which reduces the number of individual elements to three extruded flexible transparent plastic profiles, so the solar collector can be made from two extruded profiles. The main profile also forms the case housing, absorber, thermal insulation cavities with distance ribs, the drainage and assembly gutters. The two equal end sections form the distribution channel, the connections for the heat transport medium and the drainage and assembly gutters. The profiles are glued or welded together. The dark liquid medium with thermal reactive colouring material takes over the roles of the absorber and the heat conductor, as well as providing the protection against overheating. This product is claimed as economical with a small number of elements; light on materials consumption; automated; easier to handle and assemble (7 kg/m²); good for renovation as an alternative to roofing tiles; and panels can be erected over a wide area. There is higher solar efficiency because of transparent thermal insulation, and possible reciprocal use of diffused light on internal and external surfaces. It can be applied as partially transparent and offer colour-changing walls and roofs and offering adaptable forms and dimensions, e.g. trapezoidal and curved surfaces. It is easily recyclable being one material type. Currently in experimental development stage (laboratory prototype), cooperation is being sought for investment, joint venture, license, manufacturing or development agreements. For more information contact: Andrew Constantine, CATT Linz, IRCA, Regional Office, Hafenstrasse 47-51, A-4020 Linz wels, Austria. Tel: +43 662 8795 1214. Email: [email protected]
6
Photovoltaics Bulletin
Efficient power inverters Stand-alone tests conducted by Sandia National Labs on 5 kW power inverters from Sustainable Energy Technologies, showed better than 93% power conversion efficiencies across a full power range, ranking it among the most efficient inverters at this rating. Higher power conversion efficiencies mean lower energy losses when the DC output from an alternative energy source such as a fuel cell or solar panel is converted to AC required by the user. Higher efficiencies translate into lower energy costs, not only because less energy is consumed, but because a smaller power supply is needed to supply a given amount of energy. ‘Perhaps the most significant result of this testing is the demonstration of our inverter’s ability to maintain a high conversion efficiency across the full power range,’ says SET technology director, Brent Harris. ‘Although competitive inverters often have high peak efficiencies, this drops off rapidly as the load increases beyond 20% of full load. Full load efficiency is very important, since the bulk of an inverter’s energy transfer occurs at higher power levels.’ Based in Calgary, Canada, Sustainable Energy Technologies has developed and patented a software configurable power inverter platform to maximise the energy capture from a variety of alternative energy technologies and applications. For more information contact: Sustainable Energy Technologies, Suite 103A, 1439 17th Avenue SE, Calgary, Alberta T2G 1J9, Canada. Tel: +1 403 508 7177. Fax: +1 403 205 2509. Web: http://www.sustainableenergy.com
Zero net energy houses Work to construct up to 20 local houses with state-of-the-art, energy-efficient building technologies is to be undertaken at Harmony Heights in Lenoir City, Tennessee. The technologies are being tested through the Buildings Technology Center at the Department of Energy’s Oak Ridge National Laboratory. Four Habitat homes using ORNL-tested technology have already been constructed at Harmony Heights. The new houses, showcasing different technologies, will provide living laboratories for developing integrated building systems that lead toward net-zero energy houses of all types by 2010. Jeff Christian, director of the Laboratory’s Buildings Technology Center, said the effort is part of DOE’s Building America programme, which has resulted in more than 14,000 homes with energy-efficient and affordable features, leading to zero net energy houses.
‘Building America designs can save from 50% to 70% on energy requirements, at little or no extra cost to the builder over previous construction methods,’ said Christian. ‘The majority of the new houses in this development will be prototypes of zero net energy designs, which will ultimately be equipped to export more energy produced on site, than imported from off-site on an annual basis,’ he added. ‘Enabling production technologies include solar photovoltaics, biomass-microturbines, fuel cells and thermal and electric storage,’ he said. The first net-zero-energy home now under construction will use structural insulated panels, a raised metal-seamed roof, a biomass-fired microturbine, 2 kW of PV solar panels and a hydronic heating system. Additional plans call for the Tennessee Valley Authority to test advanced technologies in some of the houses. For more information contact: Oak Ridge National Lab, PO Box 2008, Oak Ridge, TN 37831, USA. Tel: +1 865 574 7374. Email: [email protected]
Moon mission solar cells Future moon explorers could use nanotechnology techniques to transform lunar soil into solar energy sources for a long-term habitat. Lunar regolith, or rock structure, can be refined to produce enough silicon, aluminium and other useful metals to create solar cells, says Charles Horton, a researcher at the University of Houston’s Texas Center for Superconductors and Advanced Materials. ‘At about 1500oC the regolith flows very smoothly,’ said Horton. ‘The surface is smooth enough to deposit a solar cell on. Irregularities might help generate more electrons.’ Lunar-soil cells should be able to generate about 1 V apiece. While that is unusable on Earth, the moon’s wide-open surface and unfiltered sunshine mean larger solar arrays could eventually generate about 150 kW, enough electricity for a small, long-term settlement. Creating solar cells is a power-intensive process, but methods, such as concentrating sunlight to melt lunar soil, could ‘boot-strap’ whatever power source lunar explorers bring along. Horton was speaking at a meeting sponsored by Nasa’s Institute for Advanced Multidisciplinary Research for the research community to work out nanotechnology joint goals. For more information contact: The Institute for Advanced Multidisciplinary Research. Web: http://www. tagen.tohoku.ac.jp Or contact: University of Houston, 4800 Calhoun Road, Houston, TX 77204, USA. Tel: +1 713 743 2255.
August 2002
Transparent collectors Conventional solar heat collectors are manufactured with coated sheet metal and hard glass (few are from plastic with metal). This is a labour-intensive construction, expensive and physically heavy, as well as being difficult to recycle and always darkly opaque. An Austrian entrepreneur has now developed a new solar collector, which reduces the number of individual elements to three extruded flexible transparent plastic profiles, so the solar collector can be made from two extruded profiles. The main profile also forms the case housing, absorber, thermal insulation cavities with distance ribs, the drainage and assembly gutters. The two equal end sections form the distribution channel, the connections for the heat transport medium and the drainage and assembly gutters. The profiles are glued or welded together. The dark liquid medium with thermal reactive colouring material takes over the roles of the absorber and the heat conductor, as well as providing the protection against overheating. This product is claimed as economical with a small number of elements; light on materials consumption; automated; easier to handle and assemble (7 kg/m²); good for renovation as an alternative to roofing tiles; and panels can be erected over a wide area. There is higher solar efficiency because of transparent thermal insulation, and possible reciprocal use of diffused light on internal and external surfaces. It can be applied as partially transparent and offer colour-changing walls and roofs and offering adaptable forms and dimensions, e.g. trapezoidal and curved surfaces. It is easily recyclable being one material type. Currently in experimental development stage (laboratory prototype), cooperation is being sought for investment, joint venture, license, manufacturing or development agreements. For more information contact: Andrew Constantine, CATT Linz, IRCA, Regional Office, Hafenstrasse 47-51, A-4020 Linz wels, Austria. Tel: +43 662 8795 1214. Email: [email protected]
6
Photovoltaics Bulletin
Efficient power inverters Stand-alone tests conducted by Sandia National Labs on 5 kW power inverters from Sustainable Energy Technologies, showed better than 93% power conversion efficiencies across a full power range, ranking it among the most efficient inverters at this rating. Higher power conversion efficiencies mean lower energy losses when the DC output from an alternative energy source such as a fuel cell or solar panel is converted to AC required by the user. Higher efficiencies translate into lower energy costs, not only because less energy is consumed, but because a smaller power supply is needed to supply a given amount of energy. ‘Perhaps the most significant result of this testing is the demonstration of our inverter’s ability to maintain a high conversion efficiency across the full power range,’ says SET technology director, Brent Harris. ‘Although competitive inverters often have high peak efficiencies, this drops off rapidly as the load increases beyond 20% of full load. Full load efficiency is very important, since the bulk of an inverter’s energy transfer occurs at higher power levels.’ Based in Calgary, Canada, Sustainable Energy Technologies has developed and patented a software configurable power inverter platform to maximise the energy capture from a variety of alternative energy technologies and applications. For more information contact: Sustainable Energy Technologies, Suite 103A, 1439 17th Avenue SE, Calgary, Alberta T2G 1J9, Canada. Tel: +1 403 508 7177. Fax: +1 403 205 2509. Web: http://www.sustainableenergy.com
Zero net energy houses Work to construct up to 20 local houses with state-of-the-art, energy-efficient building technologies is to be undertaken at Harmony Heights in Lenoir City, Tennessee. The technologies are being tested through the Buildings Technology Center at the Department of Energy’s Oak Ridge National Laboratory. Four Habitat homes using ORNL-tested technology have already been constructed at Harmony Heights. The new houses, showcasing different technologies, will provide living laboratories for developing integrated building systems that lead toward net-zero energy houses of all types by 2010. Jeff Christian, director of the Laboratory’s Buildings Technology Center, said the effort is part of DOE’s Building America programme, which has resulted in more than 14,000 homes with energy-efficient and affordable features, leading to zero net energy houses.
‘Building America designs can save from 50% to 70% on energy requirements, at little or no extra cost to the builder over previous construction methods,’ said Christian. ‘The majority of the new houses in this development will be prototypes of zero net energy designs, which will ultimately be equipped to export more energy produced on site, than imported from off-site on an annual basis,’ he added. ‘Enabling production technologies include solar photovoltaics, biomass-microturbines, fuel cells and thermal and electric storage,’ he said. The first net-zero-energy home now under construction will use structural insulated panels, a raised metal-seamed roof, a biomass-fired microturbine, 2 kW of PV solar panels and a hydronic heating system. Additional plans call for the Tennessee Valley Authority to test advanced technologies in some of the houses. For more information contact: Oak Ridge National Lab, PO Box 2008, Oak Ridge, TN 37831, USA. Tel: +1 865 574 7374. Email: [email protected]
Moon mission solar cells Future moon explorers could use nanotechnology techniques to transform lunar soil into solar energy sources for a long-term habitat. Lunar regolith, or rock structure, can be refined to produce enough silicon, aluminium and other useful metals to create solar cells, says Charles Horton, a researcher at the University of Houston’s Texas Center for Superconductors and Advanced Materials. ‘At about 1500oC the regolith flows very smoothly,’ said Horton. ‘The surface is smooth enough to deposit a solar cell on. Irregularities might help generate more electrons.’ Lunar-soil cells should be able to generate about 1 V apiece. While that is unusable on Earth, the moon’s wide-open surface and unfiltered sunshine mean larger solar arrays could eventually generate about 150 kW, enough electricity for a small, long-term settlement. Creating solar cells is a power-intensive process, but methods, such as concentrating sunlight to melt lunar soil, could ‘boot-strap’ whatever power source lunar explorers bring along. Horton was speaking at a meeting sponsored by Nasa’s Institute for Advanced Multidisciplinary Research for the research community to work out nanotechnology joint goals. For more information contact: The Institute for Advanced Multidisciplinary Research. Web: http://www. tagen.tohoku.ac.jp Or contact: University of Houston, 4800 Calhoun Road, Houston, TX 77204, USA. Tel: +1 713 743 2255.
August 2002