Solar Thermal History

History goes in cycles, and solar thermal history is no different. As of 2005, there is expected to be a continuing boom in the solar thermal industry, but did you know that there have been booms in the past? It's just one of the surprises you might find in our brief history of solar thermal:

Since time immemorial, people have actually relied on solar thermal energy. Without the sun, we would not have any water at all, of course.

In Western history, the first practical application of solar thermal was built by a Swiss inventor, Horace de Saussure, in 1767. De Saussure captured the sun in a "hot box" made of glass, with two boxes inside. One of these boxes was heated to 228 degrees Fahrenheit in a matter of hours. Little did he know that his invention would anticipate two kinds of solar thermal systems used centuries later, the batch heater and solar thermal air heating.

In frontier America of the nineteenth century, there were little natural resources (wood included, if you lived on the plains). Many industrious people used large metal tanks to heat water naturally, using the sun's energy.

In 1891, Baltimore entrepreneur Clarence Kemp became the first man to patent a solar thermal system. Kemp successfully marketed his invention to homes up and down the east coast of America. By 1897, a third of the homes in Pasadena, California had water heated by the sun.

1909 was (ahem) a watershed year in solar thermal. William Bailey patented his solar water heating system that separated the storage tank from an element that collected heat from the sun. This enabled the water to be stored in larger quantities inside the home. By 1918, Bailey had sold over 4,000 of his Day and Night Solar Hot Water Heaters.

There were other busts and booms in solar thermal history in the USA. In the 1920's, the discovery of natural gas in California effectively killed the solar thermal industry there. In pre-war (WW II) Florida, over half the homes used solar to heat water. After the war, declining electricity rates put a stop to Florida's solar thermal industry. Today, rising oil costs and shrinking solar thermal costs are bringing about another boom across the USA.

Solar thermal around the world

In Japan, solar thermal has been an effective way of heating water in a nation lacking cheap sources of energy. As early as 1969, there were 4 million solar water heating tanks on the roofs of Japanese homes. As the price of oil there dropped then rose again over the decades, the solar thermal industry there has busted then boomed again. Today there are 10 million solar thermal systems at work in Japan.

In Israel, like other nations, there have been wild fluctuations in the price of oil. Unlike its neighbors, Israel has no oil supply of its own. In the 1960's, a lack of oil resulted in a boom in solar thermal systems there. When the price of oil dropped, so did solar thermal sales. Today, a whopping 90% of Israeli homes use solar hot water heating.

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