In the 1880’s the first photovoltaic cells were built. They trapped the sun’s light and converted it into solar energy. They were made of selenium and were efficient by 1%-2%. In 1891 the first commercial solar water heater was patented by an American. This was another benchmark in the history of solar power.
Solar power again emerged in 1970’s, as oil prices soared on the open market. This was a great opportunity for the use of solar power to increase. Around 3,000 photovoltaic systems were set up. In the 1990’s people began to realize that total dependence on foreign countries for oil and petroleum was a cause for concern.