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What to expect
We will build a simple solar tracker that does not require an external electrical source to operate it.
Connections
The previous activity taught us about the summer/winter solstice and the spring/fall equinox. Here, we will start building a simple solar tracker to review how solar panels power DC motors and experiment with different wiring options to understand the movement of the unplugged solar tracker.
Community Connection and Solar Fun Facts
Materials
Two solar panels
DC gear motor
Laser-cut wood base
3D-printed (plastic) Solar panel mount
Two wire connectors
Instructions
In this activity, we will build an unplugged desktop solar tracker that moves and points to where the light is shining. This simple solar tracker will not need computer chips, computer programs, or batteries to operate. How exciting! The only condition is that it needs to be in direct sunlight. Please also note that the DC motor we use for this activity is a little different because it’s equipped with a gearbox. We want to slow down the spinning speed as the solar tracker doesn’t need to move at the speed of the DC motor.
Part 1. Understanding the basic concept of solar panel connection to DC motor
First, we need to understand how different connections can change the spinning direction of the DC motor. We have already learned that a solar panel can power a DC motor to spin in a particular direction.
Figure 1. Solar panel to DC motor connection (clockwise spinning)
The DC motor will spin clockwise if the wires are connected as Shown in Figure 1.
Figure 2. Solar panel to DC motor connection (counter-clockwise spinning)
2. If you switch the wire connection, the DC motor will spin counter-clockwise, as shown in Figure 2.
Figure 3. Checking the DC motor spinning direction
3. You can test this by connecting the wires and using the halogen light provided to see which direction the DC motor is spinning. It can be hard to see the spinning direction. To visualize it, you can add a piece of masking tape on the tip of the DC motor, as shown in Figure 3. Make sure you test the other spinning direction by switching the wire connection.
Figure 4. Two solar panels connected to the DC motor
4. We will now connect both solar panels to the DC gear motor, as shown in Figure 4. You need to ensure the panels are connected to the DC motor using the wire connections demonstrated in Figure 4.
Once two panels are connected to the DC motor, there wouldn’t be any motion (rotation) under the sunlight (or halogen light) because the voltages from the solar panels are canceled out. Test this with the halogen light to assess the motion of the DC motor based on the solar panels’ connection.
We will apply this concept to build your unplugged solar tracker next.
Part 2. Building an unplugged solar tracker
Figure 5. DC motor inserted into the solar panel mount
First, we need to insert the motor into the 3-D printed solar panel mount, as shown in Figure 5.
Figure 6. Solar panels connected to the DC motor
2. Once the DC motor is installed, we will finish the solar panels’ wire connection to the DC motor using the wire connectors, as shown in Figure 6.
Figure 7. DC Motor installed on the laser-cut wood base
3. Next, you need to install the DC motor on the laser-cut wood base, as shown in Figure 7.
Figure 8. Two solar panels were installed on the mount
4. Finally, you can install the two solar panels on the 3D-printed mount, as shown in Figure 8.
Now, you are ready to go out and test your unplugged solar tracking system! If it’s cloudy or rainy outside, you can test your tracker inside using the halogen light.
Think about it
In this activity, we built an unplugged solar tracking system.
How should it operate when the installation is done?
What is the purpose of the solar tracker like this?
What will happen if you connect two solar panels to the DC motor differently from how we connected them in this activity? (For example, the two red wires and the two black wires are connected together.)
Was there anything about this activity that surprised you?
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Next Time
In the next activity, we will start building another type of solar tracker requiring computer programming.
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