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Can solar energy power everyday objects efficiently?

As this image shows, even powering something as simple as a park light can require a large solar panel to gather the necessary energy.
As this image shows, even powering something as simple as a park light can require a large solar panel to gather the necessary energy.
iStockphoto/ThinkStock

It's hard to argue against solar energy. The sun sustains most life on our planet. Plants absorb energy from the sun and convert it into chemical energy. Herbivores get energy by eating plants while carnivores get energy by eating herbivores and other carnivores. Trace the energy back to the source and you arrive at the sun.

But converting solar energy into electricity is tricky. Photovoltaics can do the trick. These are materials that can absorb photons -- the basic quantum units of light -- and convert them into electricity. Edmond Becquerel discovered the photovoltaic effect in 1839 while experimenting with an electrolytic cell. Becquerel noted that the output of the cell increased when exposed to light. But it would take more than a century to advance photovoltaics to the point that they were efficient enough to generate the electricity needed to power simple electrical devices.

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In 1954, Bell Telephone Laboratories built a solar cell with an efficiency of about 6 percent [source: American Physical Society]. That means the cell was able to convert 6 percent of the total energy it received into electricity. That's incredibly inefficient -- 94 percent of the energy from the sun goes to waste. You'd have to link many solar cells together into solar panels to generate a significant amount of electricity.

Today, engineers and scientists have advanced solar panel technology so that efficiencies of 30 percent or greater are possible. That means you don't need as many of today's solar cells to generate any given amount of electricity. And you must align the cells in a single layer across an area to receive enough sunlight to meet electrical needs. For a home, this might mean covering a significant percentage of the roof with solar cells or building a freestanding solar panel somewhere on the property. Large businesses might need enough solar panels to cover a football field or more to meet energy needs.

Solar cells are also expensive. While the energy solar cells provide is free, the cost of materials and installation tend to be high. Installing solar cells for your house requires a significant up-front investment. Some states provide tax incentives to help offset the cost and you may even be able to sell some power back to the electrical grid, depending upon your power company. But solar cells are still a hefty investment in the short term.

Despite all those caveats, solar cells are still a great way to get electricity. They can pay for themselves after a few years and the energy they provide doesn't contribute to pollution. Once a system pays for itself, the electricity it generates is essentially free!

Next, we'll look at some efficient uses for solar energy.

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Coating your roof with solar panels may allow you to get off the power grid or sell electricity back to it.
Coating your roof with solar panels may allow you to get off the power grid or sell electricity back to it.
iStockphoto/ThinkStock

Now that solar cells can convert at least 30 percent of the sunlight they receive into electricity, it's easier to make the argument for solar power. But before you rush off to cover your home in solar panels you'll need to take a few factors into consideration:

  • Does your local government provide tax incentives to convert to solar power?
  • Does your power company allow net metering?
  • Does your home receive direct sunlight for several hours on a typical day?

While converting to solar power is great for the environment, it's going to impact your wallet. You can make your own solar panels by purchasing solar cells and wiring them together, which can save you some costs up front. But if you want to qualify for tax incentives or net metering, you may have to hire a professional installation crew and purchase your panels from approved sources. Some of the cost will be offset through tax savings but the initial cost will be higher.

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Assuming you can make that investment and that your home receives enough sunlight, you can generate enough electricity to power your appliances and other electrical devices purely on solar power during the day. What happens next depends upon your plan.

If you stay connected to the power grid, you'll want to look into net metering. With enough solar panels, you'll generate more electricity than you need to power your home. Some power companies will allow you to feed that excess electricity back into the grid. The company credits you for the power you've generated. When the sun goes down, you'll begin consuming electricity from the power company. If you consume less electricity than you produce every 24 hours, you'll have a net gain in credit. Otherwise, you'll have a significantly reduced electric bill.

The other option is to go off the grid completely. Since you can only capture solar energy while sunlight hits the solar panels, you'll have to install batteries to store excess energy during the day. At night, you'll use these batteries to power your home. The next time sunlight hits the panels, the batteries begin to recharge.

In either case, it's not hard to generate enough electricity to reduce or even eliminate your power bill, assuming your home gets enough sunlight during the day. It'll take a few years for the savings to pay off your initial investment and you'll occasionally need to replace panels and batteries, but in the long run you should save money. You'll also reduce your carbon footprint in the process.

Another option you can look into is to install a solar water heater. These devices use solar energy to heat water before storing it in a tank. Most systems use a conventional water heater to further increase the water's temperature. Solar water heaters reduce the overall amount of energy you need to heat your water, reducing your demand for electricity from a power grid.

As we invest more money into solar panel technology, we should see production costs decrease and efficiency increase. In a few years solar panels may not require as large an investment and will help reduce the environmental impact we create with our need for electricity.

Learn more about solar power and related topics by following the links on the next page.

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Sources

  • American Physical Society. "This Month in Physics History: April 25, 1954: Bell Labs Demonstrates the First Practical Silicon Solar Cell." APS Physics. 2010. (Nov. 29, 2010) http://www.aps.org/publications/apsnews/200904/physicshistory.cfm
  • Carter, J. Stein. "Photosynthesis." Clermont College. Nov. 2, 2004. (Nov. 16, 2010) http://biology.clc.uc.edu/Courses/bio104/photosyn.htm
  • Knier, Gil. "How do Photovoltaics Work?" NASA. 2002. (Nov. 15, 2010) http://science.nasa.gov/science-news/science-at-nasa/2002/solarcells/
  • Make Solar Panel. "Being Practical About Solar Panel Applications." Sept. 28, 2010. (Nov. 16, 2010) http://buildyourownsolarpanel.us/solar-panels/being-practical-about-solar-panel-applications.html
  • PVResources. "A walk through time." 2010. (Nov. 16, 2010) http://www.pvresources.com/en/history.php
  • Renewable Energy Expert. "The Most Common Solar Energy Uses." 2008. (Nov. 16, 2010) http://www.renewable-energy-expert.com/the-most-common-solar-energy-uses.php
  • The NPD Group. "Uses of Solar Energy." Solarbuzz. 2010. (Nov. 17, 2010) http://www.solarbuzz.com/Applications.htm
  • Union of Concerned Scientists. "How Solar Energy Works." Dec. 16, 2009. (Nov. 17, 2010) http://www.ucsusa.org/clean_energy/technology_and_impacts/energy_technologies/how-solar-energy-works.html
  • U.S. Department of Energy. "Active Solar Heating." Energy Savers. 2010. (Nov. 17, 2010) http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12490
  • U.S. Department of Energy. "Exploring Ways to Use Solar Energy." Energy Savers. 2010. (Nov. 17, 2010) http://www.energysavers.gov/renewable_energy/solar/index.cfm/mytopic=50011
  • U.S. Department of Energy. "Outdoor Solar Lighting." Energy Savers. 2010. (Nov. 17, 2010) http://www.energysavers.gov/your_home/lighting_daylighting/index.cfm/mytopic=12170
  • U.S. Department of Energy. "Small Solar Electric Systems." Energy Savers. 2010. (Nov. 17, 2010) http://www.energysavers.gov/your_home/electricity/index.cfm/mytopic=10710
  • Whitaker, Bill. "Is Solar Power Really Practical?" CBS Evening News. July 7, 2008. (Nov. 16, 2010) http://www.cbsnews.com/stories/2008/07/07/eveningnews/main4239590.shtml

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