SUNPOWER: The Earth's largest energy resource

Diagram of Anasazi Cliff Dwelling

Every day, the sun showers the Earth with abundant energy. Although many people think of solar energy as a new and emerging technology, capturing this energy source for heat was used historically by many ancient civilizations populations, including those in the Southwestern United States. Hundreds of years ago, the Anasazi Indians designed their cliff dwellings to maximize the solar gain in winter by building into the cliffs. They positioned their buildings under the cliff overhang to allow the winter sun to reach their homes. The sheltering overhang also minimized radiant heat loss at night, and protected them from cold winds. They also used small window openings to conserve heat, and built their structures with heavy stone and clay materials that absorbed and held the solar heat, releasing it slowly after the sun had set. In summer, the cliff overhang provided shade from the high summer sun angle and the mass helped their homes remain cool in the hot months of summer.

These same basic principles of solar design are being used today to make homes comfortable with little assistance from outside energy sources, and more recent inventions allow us to obtain electrical energy from the Sun as well. Making use of the sun's free energy makes particular sense because of the many problems associated with fossil fuel use. As the human population continues to grow and energy demands increase, environmental problems like air and water pollution, global warming and depleted fossil fuel reserves make switching from our reliance on nonrenewable energy sources to renewable sources even more essential. Although every location on Earth receives sunlight, the amount received varies greatly depending on geographical location, time of day, season and clouds. The southwestern United States is one of the world's best areas for sunlight. New Mexico receives more than 3200 hours of sunshine per year, twice the sunlight received by other regions in the United States. The state's average daily energy consumption of over 900 billion BTUs is equivalent to the amount of solar energy received on an average day within an 18 square mile area. This energy is equivalent to 161,000 barrels of crude oil. Hence, the potential for solar energy development in our state is great. For a more detailed look at the solar resource, see The Solar Resource.

There are several primary solar energy technologies including

  • Photovoltaics (for obtaining electricity),
  • Passive solar design (heating, cooling, and hot water)
  • Active solar thermal (heating, cooling, and hot water)
  • Solar thermal electric (large scale electricity generation from solar)
  • Solar cooking
  • Solar distillation
  • Solar water pumping

A passive solar system is a solar water-heating or space-heating system that captures and moves sun-heated air or water without using pumps or fans. An active solar system, on the other hand, is a system that moves sun-heated air or water using pumps or fans. Many homes incorporate several aspects, such as passive solar design and photovoltaics, and sometimes other renewable energy forms such as wind systems, and are totally energy sufficient and not connected to or dependent upon utility power lines.

To learn more about solar energy, see our Solar Primer: From Oil Wells to Solar Cells.

To learn more about passive solar, see our concise guidelines, or detailed guidelines.