Solar Power Technologies and Their Practical Applications

Solar power is energy, usually in the form of electricity, which comes from sunlight. The scale of the energy conversion project typically determines the technology used. Large commercial electricity generators may use CSP (Concentrated Solar Power systems), based on lenses, mirrors and tracking systems, while smaller installation will often use photovoltaic cells. Most systems require some form of energy storage to provide backup at night.

Most of the major solar energy production facilities use CSP systems to convert sunlight into electricity. The largest plant in the world is located in California's Mojave Desert, producing an output of more than 350 MW. Spain also has several large CSP energy plants. The ideal locations for conversion of sunlight into electricity are places that get a lot of sunlight year round.

CSP systems use lenses or mirrors to concentrate sunlight into a small beam. These will track the sun as it moves across the sky, concentrating its energy onto a small point where it heats up a working fluid, and generates electricity in the same way as a conventional plant.

A study by various international organizations has estimated that CSP could provide 25% of the worlds electricity requirements by the year 2050. At the moment Spain is the world leader in these technologies. CSP stations are best located in desert areas, such as Africa, Mexico and the south-western states of the US.

The other type of solar power being practically used in the world today uses photovoltaic technologies. PV cells are semiconductor devices that are able to be contained in a fairly small panel. They produce a reliably small amount of DC electricity when sunlight is absorbed into the panel. Because of the manageable size of the panels, these systems are scalable. In order to produce sufficient electricity, several panels are installed together.

PV cells are especially useful for small installations, such as one that produces enough electricity for a home. They can also be used for something as small as powering a traffic sign with just one panel. PV panels are also practical for larger installations. Several panels are connected to produce the amount of electricity required. The Sarnier power plant in Canada produces 97 mega watts with a PV system.

Systems which produce energy from the sun clearly can not work at night time, and in common with some other green energy sources (tidal and wind power) some form of energy storage is required. There's a plant in Geesthacht, Germany that stores solar energy in the form of pumped storage hydroelectricity. Solar energy is converted to electricity during daylight hours. It's used to pump water into a raised reservoir. During the night time, water can be released, producing hydroelectricity.

Because of the cost of the batteries to store electricity, many residential PV systems are simply connected to the grid. During daylight hours, the homes use solar energy produced by the PV cells. During night and on cloudy days, electricity is purchased from the power company. The grid can also be used as a form of energy storage, because it is possible for consumers to feed power back into the grid, provided that is permitted by local electricity companies.

On their own photovoltaic cells are still too expensive to be economically viable for most homeowners. Because it's a renewable green technology, many countries are offering subsidies that tip the scales in favor of installing solar panels on homes. Residential PV installations include an inverter, which is an electronic unit that converges the DC voltage produced by the PV cells into AC which can be used by the home and fed back into the grid. Germany, Spain, France, Italy, Korea and the United States have all experienced recent growth in the PV market due either to favorable tariffs and subsidies, or to local market conditions.

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