Edmond Becquerel discovered the photovoltaic effect in 1839, laying the scientific foundation for solar cells.
Becquerel observed that certain materials produced a small electric current when exposed to light. He made the discovery while experimenting with platinum electrodes immersed in a conducting liquid, rather than with the solid semiconductor panels used today.
The photovoltaic effect is the direct creation of voltage or electric current when light interacts with a material. It is different from solar thermal technology, which converts sunlight into heat. Modern photovoltaic cells usually use semiconductor layers, especially silicon, to separate light-generated electrical charges.
The discovery did not immediately produce practical solar power. The first working silicon solar cell appeared more than a century later, at Bell Laboratories in 1954. Albert Einstein later explained the photoelectric effect, a related but distinct phenomenon, in a 1905 paper; that distinction is a common source of confusion.