Solar Car Activity

David R. BrooksInstitute for Earth Science Research and Education

brooksdr@drexel.eduAsia-Pacific GLOBE Learning Expedition Hua Hin, Thailand, November 13-18, 2007

Activities

1. What does the sun do?2. What do solar cells do?3. Build a small car powered by a

solar cell.4. Have a contest to see which car

is the best.

Earth’s Radiative Balance

Distribution of Solar Energy

The electromagnetic Spectrum

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V

I

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R

V

With no load ("open circuit"), the solarcell produces its maximum voltage.

With no load ("short circuit"), the solarcell produces its maximum current.

With a load (resistance R) the solarcell produces power P=IV=V /R:0.0395*3.88=0.15 W3.88*3.88/100=0.15 W

2

What Does a Solar Cell Do?

The solar panel converts sunlight to electrical energy.

Sunlight shines on the solar panel

…which is transmitted through gears to the car’s wheels. Whenever there is enough sunlight, the car will move.

The motor converts electrical energy to mechanical energy...

This solar panel on this car can be adjusted so it faces the sun.The sun is in a different positionin the sky at different times of the day and at different places.

Solar cells do not store solar energy. When the solar panel is shaded, the wheels will not turn!

Fortunately, our planet has “learned” how to store solar energy! The leaves in these trees and the grass underneath them are using photosynthesis to grow. All vegetation is basically stored sunlight!

The paved street absorbs some solar energy and stores it as thermal energy. At night, the street will get cooler when its thermal energy is radiated back to the atmosphere.

Now it’s time to put our cars to the test!

While we wait for the start, we keepthe solar panels in the shade.

There they go!

There is no “off” switch andthe car keeps going in thesunlight.

The winning teamKhanomphitthaya School,Nakornsrithamarat (southernThailand): Siriwan Khiankhap Kamonrat RongmuangMaehopra Wittayakom SchoolChiang Mai (northern Thailand): Suparta Mahawan Wichuta Kuntaree Warunya KampaengRoong Aroon School,Bangkok (central Thailand): Thana Pongcharoenyong Phitchaya Chanakijseree Nuttaput Tantiverakul