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Solar power is the technology of obtaining usable energy from the light of the Sun, Solar energy has been used in many traditional technologies for centuries and has come into widespread use where other power supplies are absent, such as in remote locations and in space.



What is Solar Energy?

Solar power is the technology of obtaining usable energy from the light of the Sun. Solar energy has been used in many traditional technologies for centuries and has come into widespread use where other power supplies are absent, such as in remote locations and in space.

Solar energy is currently used in a number of applications:

  1. Heating( hot water, building heat, cooking)
  2. Electricity generation (photovoltaics, heat engines)
  3. Desalination of seawater

Its application is spreading as the environmental costs and limited supply of other power sources such as fossil fuels are realized.

Types of Technologies

Many technologies have been developed to make use of solar radiation. Some of these technologies make direct use of the solar energy (e.g. to provide light, heat, etc.), while other technologies produce electricity.

Solar design in architecture

Solar design can be used to achieve comfortable temperature and light levels with little or no additional energy. This can be through passive solar, which maximises the entrance of sunlight in very cold conditions and reduces it in hot weather; and active solar, which uses additional devices such as pumps and fans to direct warm and cool air or fluid.

Solar Heating Systems

Solar hot water systems use sunlight to heat water. These systems may be used to heat domestic hot water or for space heating. These systems are basically composed of solar thermal collectors and a storage tank. The three basic classifications of solar water heaters are:

Active systems which use pumps to circulate water or a heat transfer fluid.

Passive systems which circulate water or a heat transfer fluid by natural circulation. These are also called thermosiphon systems. Batch systems using a tank directly heated by sunlight.

A Trombe wall is a passive solar heating and ventilation system consisting of an air channel sandwiched between glazed windows and a sun-facing wall. Sunlight heats the thermal mass during the day and drives natural circulation through vents at the top and bottom of the wall. During the evening the trombe wall radiates stored heat.

A transpired collector is an active solar heating and ventilation system consisting of a perforated sun-facing wall which acts as a solar thermal collector. The collector pre-heats air as it is drawn into the building's ventilation system through the perforations. These systems are inexpensive and commercial models have achieved efficiencies above 70 percent.

Solar Cells or Photovoltaic Energy

We can also change the sunlight directly to electricity using solar cells. Solar cells are also called photovoltaic cells - or PV cells for short - and can be found on many small appliances, like calculators, and even on spacecraft. They were first developed in the 1950s for use on U.S. space satellites. They are made of silicon, a special type of melted sand.

When sunlight strikes the solar cell, electrons (red circles) are knocked loose. They move toward the treated front surface (dark blue color). An electron imbalance is created between the front and back. When the two surfaces are joined by a connector, like a wire, a current of electricity occurs between the negative and positive sides.

These individual solar cells are arranged together in a PV module and the modules are grouped together in an array. Some of the arrays are set on special tracking devices to follow sunlight all day long.

The electrical energy from solar cells can then be used directly. It can be used in a home for lights and appliances. It can be used in a business. Solar energy can be stored in batteries to light a roadside billboard at night. Or the energy can be stored in a battery for an emergency roadside cellular telephone when no telephone wires are around.

Some experimental cars also use PV cells. They convert sunlight directly into energy to power electric motors on the car.