Imagine a source of energy that is infinitely renewable, nonpolluting, lasts indefinitely, has a low maintenance and operating cost, and could, in principle, be able to satisfy almost all of the energy needs of the world. Such a source is represented by devices that convert solar energy directly into electrical energy. These are called photovoltaics.
Although the fundamental process of converting solar energy directly into electricity was discovered early in the 19th century, it remained only a laboratory curiosity until the 1950s. In 1954, the first practical solar cell was designed and made by Bell Laboratories. Still the cost of the electricity generated by the first primitive cells was so high that there was little incentive to develop the technology further. Its initial important use was in the NASA space vehicles where costs did not matter and access to electrical energy and reliability were the most important considerations.
It was not until the 1970s when oil prices shot up precipitously, generating acute concern about the future of fossil fuels in our economy that the industrialized world was forced to consider photovoltaics seriously as a terrestrial power source. To encourage the development of alternative sources of renewable energy the governments of the world and in particular the United States government invested in research in photovoltaic devices and provided subsidies for their manufacture and use.
One reason it was possible at that time to consider photovoltaics seriously was that the materials and the technology needed for the