Solar energy is the energy that reaches the earth in the form of electromagnetic radiation (light, heat and mainly ultraviolet rays) from the sun, where it has been generated through a process of nuclear fusion. Solar energy can be exploited in two ways: by high temperature thermal conversion (photothermal system) and by photovoltaic conversion (photovoltaic system).
High temperature thermal conversion is the transformation of solar energy into thermal energy stored in a liquid. Devices called collectors are used to heat the liquid.
Photovoltaic conversion is the direct transformation of luminous energy into electrical energy. This is done with solar panels made of photovoltaic cells (of silicon and germanium).

Advantages: it is a non-polluting energy and provides cheap energy to non-industrialized countries.

Disadvantages: it is an intermittent energy source, as it depends on the number of hours of sunlight a year. Also its energy yield is quite low.