Introduction:

The sun is a star which provides energy for life on earth. It is also the primary source of energy for the fossil fuels - oil, gas and coal. In one year, the amount of solar energy reaching the earth's surface is ten times greater than the world's total fossil fuel energy resources.

Some of the solar energy reaching earth is transformed into wind, hydro and wave energy.  The sun also contributes, along with the moon, to tidal movements, which can be a significant source of renewable energy.  Solar energy is transformed via photosynthesis into trees and crops which can be used to provide energy (bioenergy).  And animals eat plants and themselves produce wastes (such as dung), which are then used by humans to provide us with energy in one form or another.

We can use the heat (or thermal energy) from the sun for practical purposes including:

• Solar hot water;
• Passive solar heating of buildings; and
• Crop drying, salt production etc.

Also, solar energy can be transformed into electricity in two main ways.  Firstly the sun’s heat energy can be used in various solar thermal systems.  Secondly, the high energy part of the solar spectrum can be captured by special devices known as photovoltaic cells to produce electricity directly.

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