The amount of energy from the Sun’s radiation falling on just 1 square kilometer is about 4,000 megawatts — more than enough to light a big city. For years, researchers were trying to mop up this energy by using photo voltaic materials which released electrons when struck by light. The flow of electrons is, of course, our familiar electronic currant.
The breakthrough was achieved in 1954 by three scientists named Calvin Fubber, Gerald Pearson and Daryl Chapin at Bell Laboratories. The first solar cells were made of high quality silicon.
Solar cell (Wikipedia)