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This week's LabZone activity
July 11, 2007
Solar Speedway
Objective
Your goal is to use a solar car to discover if the position of the sun affects the power generated by solar panels.
Introduction
Check out the video to see how two clever students, Anjali and Issac, designed an easy experiment to measure how solar power changes over the course of the day. They started with a toy car powered completely by sunlight and set up their own mini race track to test how much the angle of the sun affected the speed of the car. You might find their results surprising. And if you feel the need for speed, you might want to set up your own race track and try a few solar runs of your own.
How do the panels on the solar car actually work? Solar panels are sometimes called photovoltaic cells (photo = light, voltaic = electricity) because they absorb photons of light to create an electrical voltage. Most panels are specialized arrays of semiconductors like silicon mixed with other elements that together use the sun's energy to jostle free electrons residing within the molecular complex of the panels. The freed electrons begin to flow in a united and directed fashion due to positive and negative charges set up within the panels. This, in turn, creates the electrical current that can be tapped to provide power to homes and businesses, or in the case of this project, to solar cars.
How much power is generated by a solar panel depends on its size and composition as well as its exposure to the sun. Even small changes in sunlight can reduce power production by 50% or more, so installers placing panels on rooftops must pay close attention to the roof's position and angle to the sun. In the video above, Anjali and Issac had the same idea when they set up their tests with their solar car.
In Anjali's and Issac's experiment, the car picked up speed as the angle of the sun increased after 8 a.m. But the car seemed to reach its top speed as early as 10 a.m. even though the sun continued to climb higher in the sky up until noon. If you were to try a similar experiment, do you think your results would be the same? Would using different cars make a difference? Would collecting more data each hour change the results? Perhaps you can think of additional questions to ask or different ways to run your solar car tests in your experiment.
In the next sections, we've provided directions for Anjali's and Issac's experiment as well as some suggestions for additional things to try. You can repeat their experiment exactly as they did or make modifications of your own. You'll also want do some background research to learn more about the science that links the powerful light from our nearest star to the electrical current in our cars and homes.
Drivers, start your engines—or rather, power them up, and let the sun shine on!
Experimental Procedure and Additional Information
Used with permission. Copyright © 2002-2007 Kenneth Lafferty Hess Family Charitable Foundation. All rights reserved.
Cutraro, Jennifer. 2006. Microbes at the gas pump. Science News for Kids (April 12). Available at http://www.sciencenewsforkids.org/articles/20060412/Feature1.asp .
ScienceFairZone
A Solar Water Heater
http://www.sciencenewsforkids.org/articles/20051109/ScienceFairZone.asp
For more science project ideas, go to http://www.sciencebuddies.org/mentoring/areas_of_science.shtml .
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