Solar power system – In the 1880s, selenium photovoltaic (PV) cells were developed that could convert light into electricity with 1-2% efficiency (“the efficiency of a solar cell is the percentage of available sunlight converted by the photovoltaic cell into electricity”), but how the conversion happened was not understood. Photovoltaic power therefore “remained a curiosity for many years, since it was very inefficient at turning sunlight into electricity.” It was not until Albert Einstein proposed an explanation for the “photoelectric effect” in the early 1900s, for which he won a Nobel Prize, that people began to understand the related photovoltaic effect.
Solar technology advanced to roughly its present design in 1908 when William J. Bailey of the Carnegie Steel Company invented a collector with an insulated box and copper coils.” By the mid-1950s Bell Telephone Labs had achieved 4% efficiency, and later 11% efficiency, with silicon PV cells. From then on, interest in solar power intensified. During the late 1950s and 1960s, the space program took an active role in the development of photovoltaics. “The cells were perfect sources of electric power for satellites because they were rugged, lightweight and could meet the low power requirements reliably.” Unfortunately, the cells were not practical for use on earth due to the high cost of making them efficient and lightweight, so further research was necessary.
Solar energy may have had great potential , but it was left on the backburner whenever fossil fuels were more affordable and available. “Only in the last few decades when growing energy demands, increasing environmental problems and declining fossil fuel resources made us look to alternative energy options have we focused our attention on truly exploiting this tremendous resource.”
For instance, the US Department of Energy funded the installation and testing of over 3,000 PV systems during the 1973-1974 oil embargo. By the late 1970s, energy companies and government agencies had invested in the PV industry, and “a tremendous acceleration in module development took place.” Solar energy improvements were again sought during the Gulf War in the 1990s.