Solar energy in one form or another is the source of nearly all energy on the earth. Humans, animals and plants have always relied on the sun for warmth and food. People continue to harness the sun’s energy in other ways as well, for example, fossil fuels, which are actually plant matter from a past geological age. When we use the fuels for transportation and electricity generation, we are really just using stored solar energy from millions of years ago. Similarly, biomass converts the sun’s energy into a fuel, which can then be used for heat, transport or electricity.
Wind energy, used for hundred of years to provide mechanical energy or for transportation, uses air currents that are in fact created by solar heated air and the rotation of the earth. Today, wind turbines convert wind power into electricity as well as its traditional uses. Even hydroelectricity is derived from the sun. Hydropower depends on the evaporation of water by the sun, and its subsequent return to the Earth as rain to provide water in dams.
Photovoltaics (often abbreviated as PV) is a simple and elegant method of harnessing the sun’s energy. PV devices (solar cells) are unique in that they directly convert the incident solar radiation directly into electricity, with no noise, pollution or moving parts, making them robust, reliable and long lasting.