Almost all non-nuclear energy on earth comes from the sun in one way or another. Gasoline and other fossil fuels come from plant matter, which gains its energy from the sun. Hydroelectric and wind power both come from the sun through complex processes. Direct and conscious of manipulation of solar energy has been around for a very long time, at least since the time of Socrates, who said
Humans have been trying to figure out how to improve our efficiency for a very long time, and passive solar design is one of the first ways that we actively made use of the sun. Passive solar energy is when a building is constructed in a way that maximizes the possible heat from the sun. It is one of the earliest ways that humans made use of the suns energy directly. One of the first uses of active solar power was a steam-powered engine that powered a water pump. The concept of solar radiation powering a steam engine translated into a steam engine powering a turbine, which paved the way for industrial solar-powered electricity generation. The concept of solar powered steam generators is one that is still used to this day.
The next innovation in solar power was photovoltaic cells. Photovoltaic cells are what we usually refer to as solar cells. Photovoltaic cells can be put almost anywhere sunny, and are far more practical for private use than steam generators. Photovoltaic are now a major contributor to the solar industry. Today, solar energy is growing faster than all nonrenewable energy sources combined, which bodes well for the future of clean energy.