CHAPTER 5 Photovoltaics – Energy from Sand

The term ‘photovoltaics’ comes from two words, ‘photo’ and ‘Volta’; photo stands for light and comes from the Greek phõs, or photós. The Italian physicist Alessandro Giuseppe Antonio Anastasio Count Volta, who was born in 1745, was the inventor of the battery and together with Luigi Galvani is considered to have discovered electricity. There is not much that associates him with photovoltaics. However, in 1897, 70 years after Volta's death, the measurement unit for electric voltage was named volt in his honour. Photovoltaics, or PV for short, therefore stands for the direct conversion of sunlight into electricity.

While experimenting with electro-chemical batteries with zinc and platinum electrodes, the 19-year-old Frenchman Alexandre Edmond Becquerel found that the electric voltage increased when he shone a light on them. In 1876 this phenomenon was also proven with the semiconductor selenium. In 1883 the American Charles Fritts produced a selenium solar cell. Due to the high prices of selenium and manufacturing difficulties, this cell was not ultimately used to produce electricity. At the time, the physical reason why certain materials produce electric voltage when radiated with sunlight was not understood. It was not until many years later that Albert Einstein was able to specify the photo effect that causes this. He eventually received the Nobel Prize for this work in 1921.

The age of semiconductor technology began in the mid-1950s. ...

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