Build Your Own Solar Car

In the post from re-energy they gave an idea for solar car that you can built yourself.

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.

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.

the exact instructions are here.

You can 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.