SOLAR THERMAL: Putting the Sun’s Heat to Work

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The sun’s heat is an important source of energy. In nature the sun warms the earth and the atmosphere and causes the wind to blow. People have tapped the sun’s energy to warm their homes, dry clothes, cook food, and boil water. Even the White House began using solar panels to heat water during the 1970s. When solar thermal energy is concentrated, it can be used to generate steam that spins turbines to generate electricity.

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From Etienne L. Trouvelot, Astronomical Drawings. Plate II, Solar Protuberances. Observed on May 5, 1873 at 9h, 40m. A.M. New York: C. Scribner’s Sons, 1882.

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Smithsonian Secretary Charles G. Abbot with assistants testing a solar engine, 1935

Charles G. Abbot with assistants testing a solar engine, 1935. Smithsonian photo

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Wash day towel, around 1942

Sometimes using solar energy can be as simple as a clothesline. This embroidered towel is one of a set of seven, each depicting a domestic chore done on a given day. Traditionally, Monday was wash day.

Gift of William E. Kost; Smithsonian photo

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Solar water heater panel used on the White House, 1979

President Jimmy Carter had solar panels, including this one, installed on the White House roof in 1979. Rather than generating electricity, water circulated through tubes in the panels and absorbed solar heat. The panel provided hot water for use by the president's staff and family. President Ronald Reagan ordered the panels removed in 1986. As energy costs fell public enthusiasm for solar power waned, only to rebound in the 21st century. Newer solar panels, installed during the presidencies of George W. Bush and Barack Obama, supply hot water and electricity to the White House today.

Gift of Unity College; Smithsonian photo

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President Jimmy Carteron the roof of the White House inspecting solar thermal panels, 1979

President Jimmy Carter inspects White House solar thermal panels, 1979. He remarked, “A generation from now, this solar heater can either be a curiosity, a museum piece . . . or it can be just a small part of one of the greatest and most exciting adventures ever undertaken by the American people: harnessing the power of the sun . . .” Photo courtesy of Jimmy Carter Presidential Library

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Solar tea maker, around 1983

During the 1970s, war and political turmoil in the Middle East resulted in embargos on oil imported to the United States. The restrictions caused sharp increases in the cost of energy. Entrepreneurs responded with many products that promoted energy conservation. To make solar tea one simply filled this jar with water, put in tea bags, and closed the top. Leaving the jar sit in the sun for a few hours allowed solar heat to brew the tea.

Gift of Harold D. Wallace Jr.; Smithsonian photo

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Solar One project to generate electricity for the grid, Barstow, California, 1982. Courtesy of Sandia National Laboratories