Environmental Engineering Reference
In-Depth Information
5
5
Photovoltaics - Energy
from Sand
The word ' photovoltaics ' comes from the two words ' photo ' and ' volta. ' In this
case 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
the discoverer of electricity. There is not much that associates him with photovolta-
ics. However, in 1897, 70 years after Volta's death, the measurement unit for electric
current was named volt in his honour. Photovoltaics therefore stands for the direct
conversion of sunlight into electricity.
While fi ddling with electro-chemical batteries with zinc and platinum electrodes,
the nineteen-year-old Frenchman Alexandre Edmond Becquerel found that the elec-
tric voltage increased when he shone a light on them. In 1876 this phenomenon was
also proven with semiconductor selenium. In 1883 the American Charles Fritts
produced a selenium solar cell. Due to the high prices of selenium and manufactur-
ing diffi culties, this cell was not in the end used to produce electricity. The physical
reason why certain materials produce electric voltage when radiated with sunlight
was not understood at the time. 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. The semiconductor
material silicon, which often occurs naturally, became all the rage in technology,
and in 1954 the fi rst silicon solar cell fi nally made its appearance at American Bell
Laboratories. This was the basis for the successful and commercial further develop-
ment of photovoltaics.
