Solar Economy

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Fact is higher in Finland because there is less volume and little competition. TEChNoloGy adVaNCES, CoSTS droP Fortum does not develop solar panel technology, but it does fund related projects at research facilities and universities. Tampere University of Technology in Finland, for example, is developing high-efficiency cells that could increase the efficiency of solar panels to nearly 50%. The efficiency of crystalline silicon cells is about 15%. The efficiency indicates how effectively the solar panel can convert the received solar radiation into electricity. At 15% efficiency, a panel with a nominal output of 1,000 watts per square meter generates 150 watts of electricity in ideal conditions. ”The efficiency of the crystalline silicon panels dominating the markets has improved an average of 0.3% a year. The best cells now have an efficiency of over 20%,” Eero Vartiainen says. With crystalline silicon technology, in which one cell absorbs only a certain part of the sunlight’s spectrum, the maximum efficiency achievable is about 30%. The efficiency of multi-junction cells can climb to as high as 50%. Multi-junction cells have multiple layers of cells that are made from different materials and each cell absorbs different parts of the sunlight’s spectrum. Today the cells produce electricity more efficiently, the price of the silicon used as a raw material for them has decreased and manufacturing processes have improved. The price of the technology is no longer an obstacle to the mainstreaming of solar electricity. lEarNiNG From PraCTiCal ExPEriENCE Fortum is gaining experience in the use of solar electricity at a number of sites in Finland and Sweden. The biggest is in Glava, Sweden, near Karlstad, where a one hundred-kilowatt solar electricity plant has 18 Fortum forAgendA been installed at a local solar panel factory and is connected to Fortum’s grid. According to Eero Vartiainen, the Glava facility is testing and studying solar electricity’s impacts on the grid. Solar radiation fluctuates rapidly and that causes sudden voltage variations. Such ”harmonic voltage oscillation” is unfavourable for the grid, and batteries or other forms of electricity storage to level out the fluctuations have been studied. In Mankkaa, Finland, 40 m2 of solar panels have been installed on the roof of the City of Espoo’s car depot to generate electricity for the city’s electric vehicles; construction of the site is a joint effort between the City of Espoo and Fortum. The 55-kilowatt system is designed to meet the annual consumption needs of 15 vehicles. Any surplus electricity generated can be used for the facility or it can be fed to the grid. At night, on cloudy days and when the panels are covered with snow, the vehicles can be charged from the grid. At a residential building under construction in Espoo’s Mäkkylä area, the rooftop solar panels to be installed will generate energy for the shared-use electric car and for the building’s common areas. The residential building, scheduled for completion in spring 2012, is part of the Sustainable Urban Living concept by Fortum, Skanska and ABB. riGhT SiziNG iS imPorTaNT In the near future, it will be financially feasible for multi-story buildings to use solar energy to produce the electricity needed in the common areas. Site-specific, smallscale solar electricity systems would be great also for all detached houses. ”Ideally, solar electricity would cover 15–20% a detached houses annual consumption. In a house that does no tuse electric heating this would translate to 5–7 m2 of panels. It is not feasible to over-size the system because selling A solar panel system (20–30 m) for a detached house can cover 15–20% of the household’s annual consumption. Panels are installed at a 15–70 degree angle, depending on the amount of light and the time of year. Buildings must be designed so that vegetation and any structures in the area do not block the sunlight from reaching the panels.

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