1. Solar Car Activity David R. Brooks Institute for Earth Science Research and Education brooksdr@drexel.edu Asia-Pacific GLOBE Learning Expedition Hua Hin, Thailand, November 13-18, 2007

2. 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.

3. Earths Radiative Balance

4. Distribution of Solar Energy

5. The electromagnetic Spectrum

6. + - + - + - V I I R V With no load ("open circuit"), the solar cell produces its maximum voltage. With no load ("short circuit"), the solar cell produces its maximum current. With a load (resistance R) the solar cell produces power P=IV=V /R: 0.0395*3.88=0.15 W 3.88*3.88/100=0.15 W 2 What Does a Solar Cell Do?

7. The solar panel converts sunlight to electrical energy. Sunlight shines on the solar panel

8. …which is transmitted through gears to the cars wheels. Whenever there is enough sunlight, the car will move. The motor converts electrical energy to mechanical energy...

9. This solar panel on this car can be adjusted so it faces the sun. The sun is in a different position in 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!

10. 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.

11. Now its time to put our cars to the test! While we wait for the start, we keep the solar panels in the shade.

12. There they go! There is no off switch and the car keeps going in the sunlight.

13. The winning team Khanomphitthaya School, Nakornsrithamarat (southern Thailand): Siriwan Khiankhap Kamonrat Rongmuang Maehopra Wittayakom School Chiang Mai (northern Thailand): Suparta Mahawan Wichuta Kuntaree Warunya Kampaeng Roong Aroon School, Bangkok (central Thailand): Thana Pongcharoenyong Phitchaya Chanakijseree Nuttaput Tantiverakul