Photovoltaic Systems
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The untapped energy potential of the sun is enormous. For instance, scientists have surmised that a single day's worth of sunlight, if properly harnessed and converted, could supply the entire energy needs of the United States for two years, and that a daily dose of solar energy outpaces that of the world's entire fossil fuel energy by a ratio of one thousand to one. Photovoltaic (PV) systems act as the mediator between the sun and the desired energy by converting sunlight directly to electricity. Research and development in the closing years of the 20th century pushed the technology within the grasp of those wishing to market it to a mass audience in the consumer and industrial worlds. PV systems were finding increasing employment in households, automobiles, and remote power systems, and for telecommunications, lighting systems, and a range of other applications. Over one million homes around the world were powered by photovoltaic cells, according to Appropriate Technology, the bulk of them in developing countries that received significant funding for the introduction of solar power.
While the efficiency of electronic components for electrical systems improved rapidly through the 1990s and into the first decade of the 2000s, the amount of power drawn from electric utilities continued to escalate and the solution to the increased energy demand was far from certain by mid-decade. Solar energy squared off with fuel cells, wind power, biomass, and other technologies for predominance in the renewable market. Though solar power was among the most hotly anticipated of all renewable energy sources, by the beginning of the twenty-first century, the sun accounted for only about one percent of all the renewable energy consumed in the United States.
Solar power continues to be less cost efficient than conventional power. A 50-kilowatt system, which is the size needed to power a small office building, costs approximately $350,000 to install. Even in sunny southern states, the 80,000 kilowatt hours produced per year, which would cost $7,200 at a retail rate of nine cents per kilowatt hour, only provide a 2 percent dividend. Demand for solar power in remote areas and government incentives allow the solar industry to survive until research breakthroughs or a continued rise in energy prices will make PV systems more competitive.
The term "photo" stems from the Greek word phos, which means light. "Volt" is named for Alessandro Volta (1745-1827), a pioneer in the study of electricity. "Photovoltaics," then, could literally mean light electricity. Solar power has long been recognized as a potentially inexhaustible, inexpensive source of energy. Within solar power, there are active and passive systems that include solar thermal, heating, cooling, and lighting, and photovoltaic or solar electric, systems. Although both systems gather and contain energy, they distribute it in different ways. PV cells, panels, and arrays consist primarily of silicon, the second most abundant element on Earth, or other semiconductor materials. When these are combined with other materials, they exhibit electrical properties in the presence of sunlight, generating direct current (DC) electricity. Electrons are charged by the light and move through the silicon. This is known as the photovoltaic effect. Photovoltaic systems typically carry a life span of about 20 years, during which time maintenance and servicing are minimal, as there are no moving components. The typical PV panel in the middle years of the twenty-first century's first decade was about two feet by five feet and generated about 75 to 100 watts of electricity.
Of equal importance is the fact that there are few power generation technologies as environmentally friendly as PV systems. During operation, PV systems generate no noise, hazardous waste, or pollution. These systems are used in a wide variety of applications, including wireless and cellular communications, recreational vehicles and boats, off-grid homes, and crop irrigation systems. In developing countries, PV systems are used for water purification, water pumping, and vaccine refrigeration.
The overwhelming bulk of federal research funding for solar energy passed through the U.S. Department of Energy (DOE), particularly the National Renewable Energy Laboratory and the National Center for Photovoltaics (NCP). The latter was created to facilitate cooperative research efforts between the industry, government, and universities, and establish guidelines to help bring about a solar power industry that, by 2030, would enjoy an annual growth rate of 25 percent and would maintain a central position in the U.S. and world energy markets. Most of the government funding went to universities and industry players to develop cheaper and more efficient semiconductor materials and components while at the same time boosting total capacity and production rates. Moreover, to bring about commercial success and thus ensure U.S. leadership of the PV industry, the NCP fostered the development of PV product standards, simplified maintenance procedures, and called for the elimination of legislative and regulatory obstacles to the development and promotion of PV technology.
Technology Experience to Accelerate Markets in Utility Photovoltaics (TEAM-UP) is a program designed to assist in developing commercial markets for a wide range of solar photovoltaic technologies. TEAM-UP, managed since 1994 by the Utility PhotoVoltaic Group, is in partnership with the utility industries and the Department of Energy (DOE). It provides cost sharing for selected PV business ventures in the United States; and because funding is provided by the U.S. government, TEAM-UP support is restricted to U.S. firms.
The Utility PhotoVoltaic Group is a nonprofit association of 90 electric utilities and electric service organizations in the United States, Canada, Europe, Australia, and the Caribbean, cooperating to accelerate the commercial use of solar electricity. The DOE's $5 million grant in 1998 was awarded to 14 solar electric businesses in the Utility PhotoVoltaic Group and also helped attain an additional $27 million in private funding to be used to support 1,000 systems in 12 states and Puerto Rico.
The industry has its share of concerns. Although efforts are being made to reduce costs, solar energy systems are still rather expensive. Nonetheless, by building upgraded, innovative photovoltaic systems and equipment, manufacturers are providing jobs and reducing the rate of consumption of polluting fossil fuels. Extensive use of solar energy technology will have a beneficial impact on air pollution and global climate change. PV technology can also help generate ethanol and methanol, which are themselves quickly gaining popularity as alternative fuel sources.
The first experimenter to successfully convert sunlight into electricity was French physicist Edmond Becquerel (1820-1891), who noted the PV effect in 1839 when he built a device that could measure the intensity of light by observing the strength of an electric current between two metal plates. For over 110 years following the initial discovery of the PV effect, scientists experimented with different materials in an attempt to find a practical use for PV systems. In the late 19th century, scientists discovered that the metal...
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