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Fossil Fuels
   • Uses
   • How it Works
   • Benefits
   • Limitations
   • Geography
   • Sources


The sun is primarily a source of light and heat. But can it be our primary source of energy? Solar panels or thin films designed to collect sunlight are integral parts of the process to generate electricity by way of the sun.

The sun is our most impressive source of energy. More than one million times larger than the earth, every year the sun gives us ten times more energy than is stored in all the world’s reserves of coal and oil. Explore more about ways we can harness the sun’s energy, transform it, and put it to work to help satisfy our growing appetite for energy.

For thousands of years, we’ve used the sun’s heat to do work: drying clothes, warming water, even cooking. These "passive" uses take advantage of the sun’s energy in its natural state. Passive uses like heating water and warming buildings are still an important and effective way to manage our energy resources. Using the sun’s energy to do the work normally done by fossil fuels reduces demand for those limited resources, and avoids their negative environmental impacts.

Beyond passive uses, the sun’s energy can also be captured and transformed into electricity. These "active" applications use collectors, converters, and storage devices in order to put the sun’s energy to work in other ways. Chances are you've seen solar panels in use on homes, businesses, and even solar powered electric street signs. The most common conversion device is a photovoltaic cell, first developed for practical use in 1954.

How does it Work?
Electrical Generation
photovoltaic solar cellTo capture and transform the sun’s energy into electricity, photovoltaic (PV) cells collect the radiant energy from the sun and convert it into actual electrical current. The cells absorb the sunlight, then layers of silicon material separate the electrons out into positive and negative charges, creating electrical current. The current can either be used immediately, or stored in batteries for later use.

Solar generated power is a versatile technology that can be used to power everything from small appliances to large businesses. A few photovoltaic (PV) cells wired together can produce enough electricity to power a headset radio. Panels of cells can be mounted on rooftops to provide electricity for homes and businesses. Large arrays of solar panels can be used to produce large amounts of electricity entire cities. Experts say that if 1000 acres of land in Iowa were covered with PV panels, enough electricity could be produced to power 111,000 homes. Just think how much energy could be produced in a sunny spot like Arizona.

Solar thermal systems collect the sun’s heat and use it to heat a liquid, which can then be used to warm buildings/homes or heat water. Right now an estimated 1.2 million buildings in the US have solar water heating systems. In addition, some 250,000 swimming pools are solar heated. Sunlight in Iowa will support most solar hot-water systems, even during winter months. Solar thermal systems can be utilized on a very large scale to generate electricity.

Some of the biggest benefits of solar power center on cost and supply.

  • Supply—This resource won’t run out in the foreseeable future. (If it does, we’ll have bigger problems than increasing our supply of electricity!)
  • CostThere’s no "cost" involved in the sense that no single person or country controls the energy from the sun. The resource is ready and waiting for anyone to use, it doesn’t need to be purchased. Of course, there are costs involved in the technology needed to transform the energy into a useable form (example., photovoltaic cells to convert sunlight to electricity, or an efficient solar unit to heat water).
  • EnvironmentalAnother benefit of this energy resource is that it has no byproducts. No emissions, no waste, no threats to the environment. Solar power creates no air pollution, greenhouse gases, or radioactive nuclear wastes.

The biggest limitation of this resource right now is cost. Photovoltaic cells are still fairly expensive to develop and manufacture, making the electricity produced more expensive than power from other resources.

Solar power stations take up large areas of land and many people don't think the stations are attractive. Also silicon is used to manufacture photovoltaic cells and it comes from sand that must be mined. The process can destroy whole areas of land and upset the delicate balance of nature.

Geographical Considerations
Location, location, location. The most important factor for getting the full energy potential from the sun is where you’re trying to produce power. If you build a solar facility in a spot that gets full sun year round, you’re going to have a reliable steady source of power. In places where the sun doesn't shine all of the time, solar power is relegated to backup systems or applications where constancy is not critical.

Check it out!
Some countries rely on solar energy to meet their energy needs:

  • Cyprus is the largest per capita solar energy user. Ninety percent of houses and a major percentage of apartments and hotels are fitted with solar water heaters.
  • Over 700,000 households in Israel have solar water heaters.
  • Over 4 million solar water heaters are in use in Japan.
  • In the United States, the Department of Energy's Million Solar Roofs Initiative is encouraging businesses and communities to install solar systems on one million rooftops across the country by 2010.

What do you think?
When you weigh the benefits against the limitations of this energy resource, what is the outcome? Is this a resource we’re utilizing wisely or should we pursue the technology further? Would this resource be a good match for your community?


  1. Energy Efficiency and Renewable Energy Network (EREN) and Department of Energy. "Clean Energy Partnerships: A Decade of Success. Solar Two." (Online) http://www.eren.doe.gov/success_stories/opt_solartwo.html. July 2001.
  2. Iowa Department of Natural Resources. "Solar Power." (Online) http://www.state.ia.us/dnr/energy/pubs/irerg/solar.htmJune 2001.
  3. Sandia National Laboratories. "Sandia Labs Shares Major Solar Success With Industrial Consortium." (Online) http://www.sandia.gov/media/solarll.htm. June 2001.
  4. Solarbuzz Inc. "Solar Energy Industry Statistics: Market Share." (Online) http://www.solarbuzz.com/StatsMarketShare.htm. September 2001.
  5. World Nuclear Association. "Renewable Energy and Electricity." (Online) http://www.world-nuclear.org/info/inf10.htm. December 2001.



Solar Two Reflects on Energy
Gaze deeply into a mirror and you might just see the future of energy.

Iowa and Solar Energy

The Iowa department of Transportation (DOT) began using solar-powered equipment along Iowa’s roadways in 1997.

Solar Statistics
Get the statistics. What amount of energy can we get from the sun? More