Solar power is described simply as the conversion of sunlight into electricity. Whether gleaning information on solar technology to increase your knowledge, gathering information for a home installation, or learning more with the desire of building solar panels, solar power is a field of study that continues to grow and expand. With growing interest in green technology, attention is turning toward environmentally clean energy alternatives from building wind power to harnessing the sun's energy. Though all solar technology has the same end goal of generating energy, specific technologies work to focus solar power in unique ways based on their applications.
Concentrated Solar Power systems or CSPs, make use of mirrors or lenses and tracking systems to focus a wide area of sunlight into a single, small beam. The concentrated light is then used as a heat source for a conventional power plant. There are a wide range of solar methods beyond those of building your own solar panels, and the most developed technologies are the parabolic trough, the focusing linear fresnel reflector, the Stirling solar dish, the solar power tower, and the solar bowl. While several techniques are used to locate the sun and concentrate light, working fluid is heated in all of these systems using concentrated sunlight which is then applied for generating power or storing energy.
A parabolic trough utilizes a linear parabolic reflector placed along the focal line of the reflector that concentrates light right onto a receiver. The receiver is a tube filled with a working fluid positioned directly over the middle of the parabolic mirror. The reflector is designed to follow the sun during the daylight hours by tracking along a single axis. Building solar panels and parabolic trough systems provide the best land-use factor among all solar technologies. Acciona's Nevada Solar One outside of Boulder City, Nevada is a great example of this technology.
Focusing linear fresnel reflectors are CSPs which use several thin strips of mirror instead of the usual parabolic mirrors to focus sunlight onto a couple of tubes using working fluid. Building solar panels with the flat mirrors of focusing linear Fresnel reflectors are more cost effective than parabolic mirrors and are able to contain more reflectors within the same amount of space. This allows more available sunlight to be utilized. Focusing linear Fresnel reflectors can be used in both large and compact plants.
The Stirling solar dish, also known as a dish engine system, is made of an independent parabolic reflector that concentrates light directly onto a receiver positioned at the focal point of the reflector. The reflector tracks the sun along two axes. Parabolic dish systems provide high efficiency. The 50 kW Big Dish in Canberra, Australia is a great example. The Stirling solar dish integrates a parabolic focusing dish with a Stirling heat engine that normally drives an electric generator. The benefits of Stirling solar over photovoltaic cells are higher efficiency converting sunlight into electricity and a longer lifetime.
Solar power towers include a wide array of tracking reflectors known as heliostats that focus light on a central receiver on a tower. Power towers are considered to be the most cost effective and provide better energy storage and higher efficiency compared to other CSP technologies. The Solar Two in Barstow, California is an example of a power tower.
A solar bowl is a dish mirror that is affixed to a certain spot or structure. The receiver follows the line focus made by the dish rather than having a point focus as with a parabolic mirror. It is one of the simplest designs with lowest maintenance.
Whether building solar panels or installing premade units, specific devices and structures are manufactured to focus and concentrate solar power based on the application. Solar power as an answer to modern energy needs continues to increase in popularity due in part to environmental awareness and also to the continued development, expansion, and production of these devices.
