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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.
Uses
Passive
 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.
Active
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 , first developed for practical use in 1954.
How
does it Work?
Electrical
Generation
 To
capture and transform the sun’s energy into electricity, photovoltaic
(PV) cells collect the from the sun and convert it into actual . 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.
Applications
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
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.
Heating
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.
Benefits
 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!)
- Cost—There’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).
- Environmental—Another
benefit of this energy resource is that it has no byproducts.
No ,
no waste, no threats to the environment. Solar power creates no
air pollution, , or
radioactive nuclear wastes.
Limitations
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.
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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.
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 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?
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Sources
- 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.
- Iowa Department
of Natural Resources. "Solar Power." (Online) http://www.state.ia.us/dnr/energy/pubs/irerg/solar.htmJune
2001.
- Sandia National
Laboratories. "Sandia Labs Shares Major Solar Success With Industrial
Consortium." (Online) http://www.sandia.gov/media/solarll.htm.
June 2001.
- Solarbuzz
Inc. "Solar Energy Industry Statistics: Market Share." (Online)
http://www.solarbuzz.com/StatsMarketShare.htm. September 2001.
- World Nuclear
Association. "Renewable Energy and Electricity." (Online) http://www.world-nuclear.org/info/inf10.htm.
December 2001.
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Solar
Two Reflects on Energy
 Gaze
deeply into a mirror and you might just see the future of energy.
More
Iowa and Solar Energy
 The
Iowa department of Transportation (DOT) began using solar-powered
equipment along Iowa’s roadways in 1997.
More
Solar Statistics
 Get
the statistics. What amount of energy can we get from the sun?
More
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