What is solar energy?
Mon, Feb 09, 2009 at 11:21 AM
Solar Energy is using the sun to provide useful energy in the form of heat or electricity. Electricity is generated using a technology called Solar Photovoltaic, or Solar PV. Other uses of solar energy include water and space heating. Solar technologies can be broken down into active and passive solar techniques.
Solar energy is considered environmentally friendly because the sun is a natural energy source that does not require the burning of fossil fuels to provide heat or electricity. In addition, it is also considered renewable since the energy produced from the sun does not deplete any natural resources, and will never run out.
Solar energy, however, is what is called an intermittent source. That means that it is not always available. When it is cloudy or raining, the sun is unavailable to provide light, and the solar systems would be unable to produce energy. Therefore, many of these systems are designed with either some kind of energy storage feature, or a backup source of energy such as from the electric grid. These systems allow the end user to continue to operate when the sun is not shining.
Solar PV is the most common application in New England and the one that residents are most familiar with. PV is one of the most environmentally friendly technologies available and is very easy to install on a building or property. PV technology uses the electrical properties of materials known as semiconductors to produce electricity. When hit by sunlight, a semiconductor material creates an electrical charge which can then be transferred through a circuit to anything that uses electricity. In a PV system, these semiconductors are produced in the form of cells, which are then assembled in a structural panel. Panels can then be assembled into larger groups, or arrays, to produce increasing amounts of electricity, depending on the amount of needed. Solar arrays can vary in size to provide the electricity needed for a home, office, or larger facility.
Passive solar energy uses the sun’s energy, simply through the way the structure is oriented, designed, and/or constructed. Buildings that use passive solar design can use fewer or smaller-scale active technologies to meet the remainder of their heating and lighting needs (e.g., smaller and cheaper mechanical systems). Because the sun's energy is free, maximizing use of passive solar techniques before adding active technologies can significantly reduce ongoing energy costs.
When passive solar is not enough, supplemental heating can often be provided by other active solar technologies. Small scale water and space heating often use a solar collector that concentrates heat in either water pipes or an air handling system that then distributes the hot air or water through the building as necessary. More complex technologies such as Parabolic Trough Collectors or Evacuated Tube Collectors can be used for larger commercial and industrial heating applications.
Solar Thermal Electric
While most solar technologies are used in small-scale applications, solar thermal technologies can also be used on a much larger scale. These technologies are similar in concept to solar heating technologies, using sunlight to generate heat. They differ in that they create enough heat to power a generator which is then used to produce electricity. Utility scale applications of this technology are being tested in the Southwest United States to generate electricity.
Solar energy basics
The sun's heat and light provide an abundant source of energy that can be harnessed in many ways. There are a variety of technologies that have been developed to take advantage of solar energy. These include concentrating solar power systems, passive solar heating and daylighting, photovoltaic systems, solar hot water, and solar process heat and space heating and cooling.
Solar power can be used in both large-scale applications and in smaller systems for the home. Businesses and industry can diversify their energy sources, improve efficiency, and save money by choosing solar technologies for heating and cooling, industrial processes, electricity, and water heating. Homeowners can also use solar technologies for heating and cooling and water heating, and may even be able to produce enough electricity to operate "off-grid" or to sell the extra electricity to the utilities, depending on local programs. The use of passive solar heating and daylighting design strategies can help both homes and commercial buildings operate more efficiently and make them more pleasant and comfortable places in which to live and work.
Beyond these localized uses of solar power, utilities and power plants are also taking advantage of the sun's abundant energy resource and offering the benefits to their customers. Concentrating solar power systems allow power plants to produce electricity from the sun on a larger scale, which in turn allows consumers to take advantage of solar power without making the investment in personal solar technology systems.
Solar power technologies, from individual home systems to large-scale concentrating solar power systems, have the potential to help meet growing energy needs and provide diversity and reliability in energy supplies.
MNN Public Information from the U.S. Environmental Protection Agency