When did solar energy start being used?

Answer 1

To my knowledge, the first known intelligent and deliberate use of solar energy by humans dates back approximately 60,000 years. This is the estimated age of a house built by paleolithic humans in what is now Eastern Europe, using what is now called passive solar architecture.

This small structure, cleverly made of interlocking mammoth tusks, featured a single large opening facing due south; the opening is thought to have been designed to use sunlight to warm the abode. The structure was reconstructed and exhibited at the Museum of Natural History in New York City.

Some folks date the first use of solar energy to the use of "burning mirrors" - concentrating solar reflectors - by the Greeks and Romans ca. 100 A.D., as weapons of war to ignite fires and burn sails of enemy war ships.

Photovoltaic (PV) energy - the conversion of sunlight to electricity - dates to 1839 when the property was discovered accidentally by the French experimental physicist Edmund Becquerel, while he was experimenting with an electrolytic cell. The phenomenon was first explained in 1904 by Albert Einstein in his first published scientific paper. He explained the photovoltaic effect by inventing Quantum Theory, and it was for this that he won the Nobel Prize in 1921! Usable PV cells were first made in the early 1950's.