Solar Power is the technology of obtaining usable energy from the light from the Sun. Solar energy is currently used in a number of applications like heating water, heating a home or building and cooking.It is also used for Electricity generation using photovoltaics by way of heat engines. it can aslo be used for the de-salting of seawater(desailination).
Solar Radiation
Solar radiation reaches the Earth’s upper atmosphere at a rate of 1366 watts per square meter, 6% of that, incoming solar radiation is reflected and 16% is absorbed into the atmosphere.
Most of the sun’s energy after passing through the Earth’s atmosphere,is in the form of visible and Infrared radiations.Plants use solar energy to create chemical energy through photosynthesis. Humans regularly use this energy burning wood or fossil fuels, or when simply eating the plants.
Technologies have been developed to put to use of solar radiation.Some of these technologies make direct use of the solar energy by providing heat and light,while others are designed to provide electricity.
Solar Energy Working
Solar hot water systems use sunlight to heat water,They may be used to heat your water in your home, for space heating or to heat swimming pools.These systems are solar thermal collectors, a storage tank and a circulation loop.
The three basic classifications of solar water heaters are,Passive systems which circulate water or a heat transfer fluid by natural circulation,Active systems which use pumps to circulate water or a heat transfer fluid and finally Batch systems which are made up of a tank that is directly heated by sunlight. These are the oldest and simplest solar water heater designs, however; the exposed tank can be vulnerable to cooldown.The Active systems which use pumps to circulate water or a heat transfer fluid,and lastly Passive systems which circulate water or a heat transfer fluid by natural circulation. These are also called thermosiphon systems.
Transpired Collector
Is an active solar heating and ventilation system which consists of a perforated wall that is facing the sun, 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 in the wall. These systems are inexpensive and commercial models have achieved efficiencies above 70%. Most systems pay for themselves within 4-8 years.
Solar Cells
Solar Cells which are also referred to as photovoltaic cells, are devices that use the photovoltaic effect of semiconductors to generate electricity directly from the sun. Until recently, their use has been very limited due to the high cost of production . One cost effective use has been in small devices such as calculators with a liquid crystal display or LCDs. 
Another use has been in remote applications such as SOS telephones in motorways, remote sensing, Another use has been in powering satellites and spacecraft.
Power Towers
Power towers use a number of flat, movable mirrors which are called heliostats which are used to focus the sun’s rays upon a collector tower. The high energy at this point of concentrated sunlight is transferred to a working fluid for conversion to electrical energy in a heat engine, or in some instances, stored for nighttime usage, in order to provide a more continuous output.
In general, indirect solar power involves multiple transformations of sunlight which result in a usable form of energy.
Solar Energy production from the ocean
Thermal energy production from the ocean uses the thermal gradients present at the bottom of the ocean to generate power. These temperature differences are produced by sunlight.
Active solar systems use electrical and mechanical components such as photovoltaic panels, pumps and fans to process sunlight into usable outputs such as heating water in your home.
Concentrating solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam capable of producing high temperatures and correspondingly high thermodynamic efficiencies. Concentrating solar energy is generally associated with solar thermal applications like heating water but concentrating photovoltaic (CPV) applications exist as well and these technologies also exhibit improved efficiencies. CSP systems require direct heat from the suns rays to operate properly.
