school energy&environment

A bit of history: solar energy

Mankind has always known what happens when a sunray hits a body. If this is light-coloured or is a mirror, the energy of the sun is reflected. If it is dark-coloured, the sun’s radiation is absorbed and the body heats up.
The first solar collector is based on this principle. It was invented in 1767 by the Swiss Horace de Saussure: a “black pot” used by the first American pioneers to heat water and cook while they were travelling west. In 1891, Clarence Kemp patented the first solar energy water heater. It was a success, but human beings already knew cheaper and easier ways to heat water. Only after 80 years, following the energy crisis of 1973 and the consequent increase in the oil prices, did Kemp’s water heater develop into a more modern form, becoming the solar panel that today is enjoying growing success. Besides the thermal effect, human beings recently learned how to exploit the electromagnetic effect of the sun’s radiation. The problem is converting sunrays into electric energy by means of ad hoc devices. The process, known as photovoltaic conversion or photovoltaic effect, was discovered in 1839 by the physicist Bequerel, but its first commercial implementation took place only in 1954 in the U.S., when the Bell laboratories developed the first photovoltaic cell in single-crystal silicon, reaching a 6% efficiency. The first steps of the photovoltaic conversion took place in the semiconductor and IT sectors. The first of such implementations dates back to 1958. Today the main implementations take place on earth and the industrial production of photovoltaic cells has increased from the 1960s to date, with the consequent impact on production prices. Remarkable efficiency was achieved, up to 10-13%, which may render the exploitation of solar energy to produce electricity increasingly competitive. Remarkable yields, of up to 20%, have been obtained, which will make exploitation of solar energy increasingly competitive, for the production of electricity. This means that if the solar energy that strikes a photovoltaic panel is 100, the panel will transform 20% of this energy into useful energy, more specifically into electric energy.