Hands-on Activity: Racing with the Sun - Creating a Solar Car

Pre-Req Knowledge

Students should have completed the lesson "From Sunlight to Electric Current."

Learning Objectives

After this activity, students should be able to connect a solar photovoltaic panel to a motor and a run the motor forwards and backwards.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

Common Core State Standards - Math

International Technology and Engineering Educators Association - Technology

North Carolina - Math

North Carolina - Science

Materials List

JSS-KIT and JSS-ACC (solar car and accessory kit): The Junior Solar Sprint (JSS) kit and accessory kit may be bought separately from Solarmade with the following materials:

• solar panel
• 2 axles
• 4 wheels (sized to fit axle)
• driving gear (sized to fit axle)
• electric, DC powered motor
• different gears for motor
• drill with bits is also needed to help size gears to fit axles

Chassis materials:

• balsa wood – flat 4x 8 inch boards and ½ x ½ inch pieces
• wood glue
• paints for decoration
• paint brushes
• utility knives

Introduction/Motivation

Cars are intrinsically exciting to many students. Solar-powered cars are even more so. Very little is required to motivate students to engage in this project. Discussing solar car competitions in which college students participate and providing some statistics about those solar cars and the challenges they face can be a good way to introduce this activity.

Vocabulary/Definitions

axle: The supporting shaft on which a set of wheels revolves.

chassis: The frame that holds the body and motor of an automobile together.

conductor: A material that allows electricity to move through it easily. That is, it is a material with low electrical resistance, one in which a fairly small voltage will produce a fairly large current.

current: Movement of electrons.

photovoltaic cell: A semiconductor device that converts the energy of sunlight into electric energy.

voltage: Designates "electric pressure" that exists between two points and is capable of producing a flow of current when a closed circuit is connected between the two points (can also be considered with the analogy of elevation: just as a hill will have water flow down it, a voltage will have current flow in the direction from high to low).

Procedure

Direct students to construct their cars in the following manner:

1. Set up the car body (chassis).
2. Add the axle and wheels.
3. Add the motor.
4. Then mount the solar panels.
5. Once the vehicle is completed, begin testing (weather permitting).
6. The activity culminates in a race!

Also consider the following:

• While using the materials listed above, give students the freedom to choose their own designs.
• Photovoltaic cells do not deliver nearly as much power to a motor as a battery does. Keep your solar cars light.
• Judge where your motor should go BEFORE you add it to the body.
• Make sure your panels point towards the sun and that they are steady.

Attachments

Safety Issues

• A drill may be needed to bore out the holes for the gears and wheels. Only instructors should do this. A nail just smaller than the axle may also be used to bore out the holes if necessary.
• Glue should not be ingested.
• Use of utility knives should be supervised.

Troubleshooting Tips

If the motor is running backwards, reverse the wires.

If acceleration seems to be quite slow or the motor is not producing enough torque to get the car moving from rest, change the gear ratio.

Investigating Questions

• How can the power created by the solar cells be maximized? (A possible answer: The sun light should be striking the surface of the solar panel at about 90 degrees.)
• How can acceleration be maximized? (Work with gear ratio.)

Assessment

Questions: Ask students to answer the following questions in writing in order to gauge their comprehension:

• Did the angle of the solar panel affect the performance of your car? Why?
• How does the sun power your car? Please explain each step.
• As a class, create a histogram of the solar car results. Discuss the distribution, and what factors affect how fast each solar car travels.

Activity Extensions

If the teacher is interested, students may use these kits to compete in the Junior Solar Sprint competition sponsored by the National Renewable Energy Laboratories.

Contributors

Copyright

Supporting Program

Acknowledgements

This content was developed by the MUSIC (Math Understanding through Science Integrated with Curriculum) Program in the Pratt School of Engineering at Duke University under National Science Foundation GK-12 grant no. DGE 0338262. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.