Solar cells are most commonly made from silicon, the same material used to make computer chips. Silicon is one of the Earth's most common elements, and is a major component of sand and many kinds of rocks. A solar cell is built like a sandwich, with two layers of silicon separated by a thin layer of insulating material. All three layers work together to convert sunlight into electricity.

The makeup of a solar cell. The Pembina Institute

When sunlight falls onto the solar cell, it produces a small electric charge. Like a battery, the charge is positive on one side of the cell, and negative on the other. A wire connects the two sides of the cell, allowing electricity to flow. This flow, or current, of electricity can be used to power a small light bulb, turn an electric motor, or recharge a battery.

Solar cells are often used in locations where there isn't any electricity and where electricity is needed in small amounts. In such cases, solar cells are usually connected to batteries, allowing electricity to be stored for use during times when the sun isn't shining.

A completed solar car. The Pembina Institute

A single solar cell is able to produce only a small amount of electricity. But solar cells can be connected together on a multi-cell panel to produce larger amounts of electricity. As with batteries, the more cells that are connected to one another, the greater the current of electricity that can be produced.¹ Solar panels can produce enough electricity to power satellites, recreational vehicles, and equipment for other applications where electricity is used in large amounts.

For this project, you will be using the electricity from solar panels to power a small car. Your challenge will be to build a solar car that travels as fast and straight as possible.

¹ Solar cells connected in series (in a long chain, positive to negative, etc.) will increase the voltage of the panel. Solar cells connected in parallel (all their positive terminals to one wire, and all their negative terminals to another wire) will increase the current, or amperage of the panel. In most large commercial panels, the individual cells are connected both ways, with rows of cells in series to raise the voltage of the panel, and then those rows connected to each other in parallel, to raise the amperage.

Build It!

(Click to continue to the construction plans)

Test It!

Test your solar car in full sunlight on a smooth surface such as sidewalk. The Pembina Institute.

Test your car by placing it in bright sunlight, or under a bright (150 watt or greater) light bulb. The wheels should begin to spin quickly. If the wheels are turning the wrong direction, switch the wires connected to the motor. This will reverse the direction of the motor. You can make small adjustments to the angle of the panels, the alignment of the wheels, and the position of the motor to reduce friction, increase the power from the panels, and improve the speed of your car.

Questions Working under a bright light bulb or in direct sunlight, experiment with the angle of light hitting the solar panels. What angle gives you the fastest rotation of the wheels? How would you modify this car to make the wheels turn faster? How would you modify this design to make a car that could carry or pull a heavier load? How could you modify this design so that your car could run for short periods in complete darkness or low light situations? Sketch a plan for a solar car large enough to carry a human. What technical problems would you have to overcome to build it?

Acknowledgements
The Pembina Institute acknowledges Michael Cooke of SunWind Solar Industries, Inc. for the design of this car.