Astronomically, the sun is also a star; it being so, you could view it as a hydrogen reactor that fuses hydrogen atoms together, forming helium and releasing massive amounts of energy. This energy is then transferred through space to the earth via electromagnetic radiations that obey all the principles that govern electromagnetism such as reflection, absorption and conduction of the energy.
The sun irradiates the earth causing the ground to heat up, and heat up the air right above it inducing a convectional flow of the air. Uneven heating of the earth's surface causes wind such that colder air flows to fill the space evacuated by the rising warm air. Consequently, as wind flows above water, it causes waves. The sun's gravitational pull -- along with the moon's pull -- causes the rising and falling of tides. These end up forming wind energy, wave and tidal energy that you can use.
The sun's energy reaches the earth in two exploitable forms: heat and light energy. When exploiting the sun's heat energy, you should employ the use of a solar collector. There are various types of solar collectors, all working with the principle of concentrating the sun's heat energy and redirecting it to its place of use. Solar collectors include low temperature, medium temperature and high temperature solar collectors that are applicable for heating free space, bathing and pool water.
You can utilize the aid of photovoltaic cells that are able to convert the sun's light energy into electricity for both small-scale and large-scale consumption. Photovoltaic cells are characterized by elements that react to the sun's light by converting it to electricity. This is the same kind of technology used in rooftop solar panels; it is able to supply enough power to run a house adequately.