Now that environmental and energy issues have become popular
topics and the roofing industry continues to become more
environmentally aware, many roofing contractors are trying to find
ways to integrate energy efficiency into roof systems. And one way
to do this is by using photovoltaic roofing materials.
Most photovoltaic systems are not roofing products; they are
stand-alone photovoltaic arrays mounted onto racks on rooftops. A
photovoltaic system converts solar energy into electricity by
turning the direct current power generated by the arrays into the
alternating current power used by standard electrical appliances
and provided from the electrical grid.
During the late 1970s, the installed cost of a photovoltaic
system was more than $50 per watt of rated capacity, or about $2
per kilowatt hour (kWh). A photovoltaic system's rated capacity is
its ability to generate a specified number of watts during one hour
of full sunlight. During the 1980s, several thin-film photovoltaic
technologies were developed that promised cost reductions as demand
for high-volume automated...
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