HISTORY OF SOLAR ENERGY
The modern discovery date of the nineteenth century, when the German physicist Heinrich Hertz described the photoelectric effect. He observed that some metals emit electrons in contact with sunlight, and managed to turn them into electrical current, which occurs in photovoltaic cells.
Before photovoltaic and modern physics, since antiquity, it would have used solar energy in a surprising manner. One of the earliest references to the use of sunlight to create energy, dates from the second century BC. Indeed, the famous mathematician Archimedes, the Greek soldiers to help defend against the Romans besieging Syracuse, reportedly asked them to position their bronze shields in a carefully calculated angle to reflect the sun's rays in the direction of the sails of the boats enemies. In this way, the Greek soldiers managed to prevent the Roman ships to reach the coast, since their sails caught fire ... The same method would have been used to light the Olympic flame.
These are the same scientific principles that are used in solar cookers today. From 1950, it is used in the aerospace industry to increase the lifetime of satellites in calculators ...
The true potential of this technology was revealed in 1990, when a U.S. solar airplane, the "Sun Seeker" or Sun Seeker, traveled 4060 km. In space, the photon energy can also be used, for example for propelling a solar sail.