Basic principle of solar energy:

The sun gives out 3.7*10 ^20 MW of energy into space, out of which earth intercepts one 1.7*10^11 MW. Solar radiation is reduced in intensity in the atmosphere by clouds, dust, haze, and fog. The energy emitted by the sun in three minutes is equivalent to the world energy consumption during a year. Most of the energy we receive from the sun comes in the form of light, a short wave radiation, not all of which is visible to human eye. When this radiation strikes a solid or liquid, it is absorbed and transformed into heat energy.

The heat energy is collected in a fluid, generally water. This heat energy can be used in a solar heater or drier or can be used to run an engine. Flat plate collector or parabolic concentrated type collector is issued to collect and concentrate the solar energy and increase the temperature of the working fluid.

Applications of solar energy enjoying most success today are:

• Solar engines for water pumping.

• Solar water heaters.

• Solar cookers

• Solar furnaces.

• Photo-voltaic conversion (solar cells).

• Solar power generation.

Arrangement of solar power plant:

The Image above shows a solar power plant with a low temperature solar engine using heated water from flat plate solar collector and butane as the working fluid. This was developed in France for lift irrigation.