People have been using the sun's energy for heat, light and fire for many centuries. In the early 16th century, Leonardo da Vinci drew diagrams for reflective mirrors designed to concentrate sunlight. By 2008, 74 companies in the United States were manufacturing solar collectors, and 49 companies received 90 percent or more of their total revenue from the sale of solar products.
The Sun
The sun produces as much energy in 20 days as all of the oil, coal and natural gas deposits on our planet. In space, the energy produced by the sun is equivalent to roughly 1,300 watts for each square meter. Since some of that energy dissipates in the atmosphere, it equals about 1,000 watts per square meter when measured on a sunny day at noon here on earth. Every year, each square meter of the earth's surface absorbs energy from the sun equal to a barrel of oil.
Early Use of Solar Power
According to the U.S. Department of Energy, people were using magnifying glasses to focus sunlight and start fires as early as the seventh century B.C. In third century Greece and Rome, torches used for religious ceremonies were lit by mirrors aimed at the sun. In the first four centuries A.D., the Romans took advantage of passive solar power by installing large windows in bathhouses, placing them on the southern exposure for maximum heat. In 13th century North America, Anasazi people built their homes in cliffs that faced south, for the same reason.
The Beginnings of Solar Technology
Horace de Saussure, a scientist from Switzerland, constructed the first collector for solar energy in 1767. In 1839 in France, Edmond Becquerel conducted experiments with electrodes exposed to light, finding that such exposure increased the production of electricity. Engines using solar power were first built by a mathmetician in France, August Mouchet. Working with an assistant during the mid-19th century, he constructed steam engines that led to the development of modern solar collectors.
Recent Developments
The first completely solar-powered home was built in 1983 in the Hudson Valley area of New York. In 1984, the city of Sacramento authorized the construction of a one-megawatt electric power plant which used solar cells. Finally, Pacific Gas and Electric installed the first "grid-supported" solar power system in 1993.
Unusual Solar Applications
Solar-powered airplanes were developed in the 1970s, according to the Solar Impulse website, but the first flight wasn't taken by a human being until 1980. The Solar Impulse itself flew its maiden voyage on April 7, 2010. The plane is powered completely by solar energy, and its creators' ultimate goal is to produce planes that can fly the world using no fuel and creating no pollution.
A solar cigarette lighter uses a mirror to focus sunlight on a cigarette and catch it on fire.
A small solar panel on top of a billed hat collects solar energy, which runs a little fan attached to the bill.
A rodent repeller powered by a solar-charged battery emits sonic waves to chase away garden pests.
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