How to Build a Solar Robot

Take your robot off the grid with a solar panel.

With only basic knowledge of electronics and robotics, you can build a robot powered entirely by the sun. A robot that will never have to be plugged in to recharge can be an intriguing project for anyone interested in robotics. Virtually any kind of small robot can be adapted for solar power with the right hardware. You can even buy solar panels specifically wired to power the Mindstorms NXT controller.

Things You'll Need

• Robot body
• Motors
• Sensors
• Control electronics
• Solar panel
• Small battery pack or large capacitor
• Battery charging circuit

Instructions

1. Decide what sort of robot you want to build. If you are looking for something simple and inexpensive, consider BEAM robots. Those robots use simple analog circuits instead of microprocessors and are designed to run on small solar panels. You can find a wide variety of schematics and kits for BEAM robots through the Internet. You could also attach a solar panel to a conventional microprocessor-controlled robot, or convert one that you have already built. That will require a larger, and therefore more expensive, solar panel but will give you far more freedom to have the robot do what you want.

2. Build your robot to minimize power consumption. Make the structure as light as possible. Avoid using larger motors or a more sophisticated controller than is necessary.

3. Select a solar panel capable of powering your robot. Add up the power consumed by each of your robot's parts--controller, motors and any actively powered sensors--and find a panel that can produce the proper voltage and current. Note that solar panels are typically rated for current output in full sunlight. If your robot will be operating under less than ideal conditions, you may need a panel with a much higher current rating than what your robot actually uses.

4. Connect the solar panel to your robot. To ensure a steady flow of electricity to your robot, do not use the panel for power by itself. Instead, connect a large capacitor or a battery and charging circuit between the solar panel and the robot.

Tips & Warnings

• If you cannot find a single solar panel that has the power you need, take a number of smaller panels and wire them together--in series for more voltage, or in parallel for more current.

• You can buy solar panels with battery charging circuits built in. If you will be using a battery, one of these panels can make assembly much easier.

References

• BEAM Online
• Dexter Industries: Solar Panels
• Solarbotics
• Sundance Solar: Solar Battery Chargers