How to Make a Mini Solar Car

Hi everyone!

I am so excited to share my first instructable project with you. By following this step-by-step guide, you too can make your very own Mini Solar Car using laser cutting, 3D printing and a Micro:Bit.

To create your Mini Solar Car you will need:

Create a "chassis" or base for your car using software like Onshape. Construct a square with a small arch appended to one side, followed by several long, thin rectangular strips along the chassis. Make sure your design is approximately 15 cm by 25 cm in size, or a similar ratio. As a result, the solar car will be substantially lighter and simpler to assemble in the future. Your design should resemble the example shown above.

Then, download your design and submit it to your prefered software to start laser printing! The material we used is 0.6mm thick balsa wood. We printed two, and assembled them together in order to create a sturdier base. Other options are acrylic or any other materials you may choose.

Using a programme like Tinkercad or Onshape, make two larger back wheels. You can opt to add divots, holes, and other features to your wheels to increase their weight and grip. If you want to go a step further, you could also pick from a range of materials like rubber to stick on the outside of your 3D printed wheels to increase its grip on a variety of surfaces. You may choose to laser cut your wheels instead of 3D printing them, or even use some spare toy car wheels at home. We also added a wheel hub, which we found gave us more space between the wheel and the edge of the chassis. Hollowing out one side allows the wheel to be lighter.

Open a new project and connect your Micro:bit to your computer via an adapter. Then, start writing code. You must first download the DF-Driver extension pack from the extensions menu. It will appear on the sidebar of your Micro:bit after you press the Download button. Next, you can begin.

• Drag "motor dir speed" into the input using the pink "on button A press" button. On this block, choose "M1," "CW," and 225 as the speed.
• Choose pause under basic, then set the number to 5000.
• Drag the "servo" under the "pause" feature while choosing DF-Driver. The variables should now be "S1" and "90" degrees.
• Once more choosing pause, change the value to 5000.
• Select "servo..degree" after that, then "M1" and "O" for the degree.
• Last but not least, find motor stop and change the setting to "M1.

You're done now! Your micro:bit block code should resemble the example in the attached image.

The next step is to assemble our car! To do this, you may have to switch out items for other resources available

• Zipties
• Bluetack
• Masking tape
• Double sided tape

Using a zipties, secure your motor to the middle thicker strip dividing the two rectangles. Then, bluetack to secure the expansion board on the left side of the middle of the chassis. To the right of it, stick down the breadboard using its adhesive. Finally, secure the DF-Driver, capacitor, and MPPT as shown in the above photo using your preference of material (will vary based off of what is best suited for your chosen material for the chassis). 

To properly wire your solar car with crocodile clips, adhere to the instructions:

• Screw the positive and negative wires from the solar panel into the MPPT's longer side's inputs.
• Connect the positive wire to a capacitor on the shorter side. Use the negative and positive wires from the capacitor to connect to the expansion board.
• Connect the servo on the side opposite the micro bit.
• Connect the bread board to the remaining wiring by following the illustration.

Use insulators like wood, plastic, and other non-conductive materials to avoid a short circuit! Use smaller alligator clips and watch out for interweaving exposed wires. This makes it simple for us to detect circuit faults.

The top left photo is an example of a messy unorganised wiring. The top right shows a neater, and more organised circuit.

Use hot glue to attach one edge of the servo to the front of the chassis to create a solid support for the steering. Use hot glue once more to attach a metal axel or wooden skewer to the other bracket's midsection. The axel's components should then be glued on either side of where they touch the chassis. This will make it possible to link the servo to the front wheels and make the vehicle highly stable. After that, connect the wires to the expansion board's first set of pins from the back.

Hooray! You made it to the last step. This final step has a lot of flexibility. Where you place your solar panel as well as its angle all depends on the weather that day. Try to angle it so it can receive as much sunlight as possible. You may even choose to take it a step further and design stability structures. Before attaching your solar panel to, use any extra zipties, tape or blue tack to tidy up the wiring and any rough edges on your solar car.