Sunlight can be viewed as the ultimate renewable resource. It is the fundamental energy source for most forms of life (except some deep-ocean dwellers whose metabolisms are driven by chemosynthesis), and most forms of energy used in human society (except nuclear energy) are derived from solar energy in some form (photosynthesis drives biomass production; biomass is either used to create energy directly or converted to fossil fuels over time).
Today, the technologies most commonly used to convert sunlight into useful energy fall into two categories: solar photovoltaic and solar thermal. Solar photovoltaic (PV) cells directly convert the energy from sunlight into electrical current. PV cells are made of semiconductor materials that release electrons and create electrical current when excited by sunlight. Solar thermal energy (STE) technology converts the energy from sunlight into heat energy. Read more.