SPECIAL FEATURE Photovoltaic predictions
Metal Construction News asked three industry experts to look into their crystal balls and predict in their own words what they think the future of photovoltaics is.
The trend is to lower costs and increase effi - ciency. Costs can reduced by using less silicone (thin fi lm silicone) and developing alternate materials to silicone (cadmium indium gallium selenide). Nanotechnology can also result in reducing the amount of material used. Multi- level cells are being developed that will convert sunlight to electricity on different layers of the PV cell rather than the top surface. On a large scale, mirrors are being used to concentrate the sunlight onto PV cells to generate more electric- ity per PV area. Research is also being done for improving inverters that convert the DC elec- tricity to AC electricity.
Alan Burnett, PE, associate, Gale Associates Inc., Mountain View, Calif.
Organic photovoltaic cells use conductive organic layers for light absorption and charge transportation instead of inorganic materi- als such as silicon. Researchers are working on organic semiconductor materials to complement the established silicon-based solar cells. Organic solar cells are lightweight, transparent and fl exible. The material opens up completely new areas of application, such as portable, rollable solar cells, or integrating solar cells as aesthetically appealing features into building façades. Organic solar cells can generate electrical power under certain light conditions—in the shade and in diffused light—that cannot be utilized economically by their silicon- based counterparts. This means they can even be integrated in façades not optimally positioned to receive incident sunlight, since the surface area available for generating solar electrical power is thereby greatly increased. Researchers at BASF and its partners, such as Bosch and Heliatek, aim to develop organic solar cells that convert at least 10 percent of incident light into electrical energy by reaching a life cycle of about 10 years.
Juergen Moors, head of marketing energy, BASF Future Business GmbH, Ludwigshafen, Germany
CPV systems can save money on solar cell cost, since a smaller area of PV material is required. Because a smaller PV area is required, CPVs can use more expensive high-effi ciency tandem solar cells. To get the sunlight focused on the small PV area, CPV systems require spending extra money on concentrating optics (lenses or mirrors), solar trackers and cooling systems. CPV systems operate most effi ciently in con-
centrated sunlight, as long as the solar cell is kept cool through the use of heat sinks. Diffuse light, which occurs in cloudy and overcast conditions, cannot be concentrated. To reach their maximum effi ciency, CPV systems must be located in areas that receive plentiful direct sunlight. Because of these extra costs, CPV is far less
common today than non-concentrated PV. Still a young application, ongoing research and develop- ment is trying to improve CPV technology and lower costs to foster it usage. As long as there is sunlight, CPV and many other solar-harvesting de- vices will ensure photovoltaics will be an energetic technology for the future.
Solar Cogeneration hybrid technology can create both electricity and hot water from a combined solar photovoltaic and thermal module. (Photo courtesy of Cogenra Solar)
20 METAL CONSTRUCTION NEWS January 2013
www.metalconstructionnews.com
In the short term, prevailing innovations will be made in mounting structures. System costs will continue to decrease and that includes instal- lation time of PV module mounting. Intelligent mounting means, new materials (steel, wood and polymers) will be used more often, leading to new challenges for their long-term reliability. The fl ex- ibility of such systems will also be of importance when it comes to rooftop integration. In the long term, organic PV might also be a real game changer in terms of application and lower cost. Additionally, convergence of technology, such as smart meters or integrated junction boxes, such as we already have with some microinverter technology, provide some promise in terms of combining components and reducing the overall module and system costs. There will continue to be a decrease in overall system cost as manufacturers continue to innovate effi ciency and costs. Reductions could be as much as 10 to 20 percent per year and we will see com- modity item cost reduce as well, such as copper wiring and metals in mounting systems.
Evelyn M. Butler, director of business development, energy and industrial systems, UL, Northbrook, Ill.
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