The sun is a very powerful source of energy. Without the sun's heat and light, human life on earth would not be possible.

 All aspects of our daily life involve the use of energy: we use energy for transport, for production of food and water (pumping) and for heating or cooling our homes and offices. Fossil fuels such as oil, coal and natural gas are used most despite the fact that the amount of solar energy that reaches the earth in one day is more than sufficient to satisfy the world’s yearly energy demand.
Solar energy can be applied in many ways. Apart from simple forms of solar energy to dry clothes, heat water or buildings or dry agricultural produce (so called solar thermal energy; see Solar Heat), we can also use the power from the sun to produce electricity for households or offices (so called solar electricity or PV (from photovoltaic; see Solar Electricity)). Besides these direct forms of solar energy, also hydropower, wind and wave power originate from the energy of the sun and are in fact indirect forms of solar energy.

      
The energy of the sun can serve many purposes. One of them is to generate heat. This is what we call solar heat. Using solar collectors the sunlight is directly converted into heat.

The use of solar heat has many advantages. It is a clean, quiet and reliable energy source. Solar heating systems have been used since the 19th century. Nowadays the use of solar heat is widespread. World wide about seven million households presently use Solar Hot Water Systems.

In households connected to a public energy grid (electricity, gas) the use of a Solar Hot Water system can save 50% or more on the energy bill for domestic hot water preparation.

In remote areas without a connection to a public energy grid, solar energy is used for heating water for households and hospitals or for drying agricultural products.