Engineering Project – Reflect and Share

Final Product:

 *After fixing final

Conclusion: works or not

As you saw earlier in my previous post, my project did indeed ‘work’ in the energy conversion aspect of it. I was able to successfully demonstrate energy conversion by converting renewable energy into electrical energy. BUT, I wasn’t able to get the car to actually run, just like what I showed in the previous videos and pictures. Since the two gears could not touch, even though the DC generator could spin, the wheels could not turn because of some design failures and mistakes that I have made: the two gears that allow the wheel and the DC generator to spin, will only spin together when the car is placed on the ground (with the weight of the other materials added which pressures the two gears together). I made a mistake by placing the solar panel at a low angle of around 60 degrees, but I later found out through testing that in order for the solar panel needs to be perpendicular at the sun. so when I set the device down on the ground, the top row of cells starts to lose some sunlight which eventually stops the DC generator.

Other from the wheels not turning and the device physically not moving around, the energy conversion part did work successfully

This following video shows what the car would have looked like if the gears worked:

 *close up view of the gears if it worked 

What to do next time/mistakes I made & summarized feedbacks: 

  • Mistake: using cardboard as the base material (to hold the pieces together) = too soft and gears could not touch
    • Next time: use hard and strong materials like wood or hard plastic
  • Mistake: using a thick straw to hold the metal rod
    • Next time: use a thin and tighter straw = more stable for the metal rod when spinning
  • Mistake: Placing the solar panel at a parallel level to the ground & not placing the solar panel at a high enough angle to receive sun
    • Next time: Connect the DC motor and the solar panel together and test it first to see which angle is the best to receive sunlight effectively, then start building
  • Mistake: Not switching different times of the day to do the testing (different sunlight)
    • Next time: I should’ve done even more testing after fixing the solar panel by putting it into the sun in the morning or times around 9-11am so that the sun is still high and it would shine onto the solar panels from more above

But since the device was not allowed to be brought home, it was hard for me to do testing at certain times that I wanted

Advantages & Disadvantages: 


  • Effectively shows and demonstrates energy conversion
  • Teaches and shows how the wires connect and the energy is being converted while testing this and in the process of making the device
  • Small and transportable
  • Aesthetically pleasing/clean and simple looking (not messy)
  • Easy to start it (with button and sunlight)


  • Needs sunlight from above (morning usually)
  • Needs more complicated materials and tools ex: soldering iron, solar panel, DC generator

The science behind this project: 

“In a solar panel, if even just one of its 36 cells is shaded, power production will be reduced by more than half ” (NW WIND&SOLAR). I think that this is also one of the factors that proved the fact that the solar panel needs to be perpendicular at the light with all the cells facing the sun.

Solar panels contain photovoltaic cells made from silicon that transform the radiant energy of the sun into electricity rather than heat. When sunlight hits the panels, it collects particles of light, called photons, which separates electrons free from their atom hosts. The energy flow generated by your solar panel’s cells is sent into DC generator; converting mechanical energy to direct current electricity. Therefore, allowing the generator to spin.

Impact of the solution:

  • Reduce environmental impact: using renewable energy source & reducing air pollution
  • Reduce electric bills
  • Job creation
  • Low maintenance costs
  • Applicable in many places: as long as there is sunlight

Engineering Project – Create and Improve

Stages of development: 

Block 1&2:

Gathering materials:







1st prototype:

 In the first classes, I focused on gathering all my materials and assembling them together to figure which things work and which don’t work before I get to the more complicated parts like wiring.


Complications and Mistakes:

I had many problems with the best-fit position for the motor so that the gears could piece together not wobble around when turning. So I fixed that problem with super glue and gluing the gear to the bar so it won’t move. BUT I had to keep trying out the different positions of the motor whether it is from the very top of the gear or to the side of until I find the best fit


In the end, I fixed the gear problem and made sure that both gears with very stable with using super glue and gluing them to the metal rod

BECAUSE of this problem, I had to remove and take off the motor many times after hot gluing it, which ripped off many pieces of the cardboard and made the base very weak and soft. Therefore, I took everything apart and ‘restarted’ in order to build a new and stronger base

Block 3: 2nd prototype:

 *rebuilt the base

I called this the ‘final piece’ since this is what I thought would’ve worked before I did the testing

Changes I made to this 2nd prototype:

  • More stable base

  • Better aesthetics (originally used a cardboard square to hold up the solar panel, now changed to a piece of wood and reorganized and covered up the hot glue and marks = better aesthetics

Block 4:

Testing #1: 

In this video, I placed the car at a place with a fair amount of sunlight but, as you can see in the video, that is not enough sunlight required to power this car (this place is still a bit shady)

Testing #2: 

In this video, I moved to a place where the sunlight is more intense and this did not work as well… which told me that a higher level of sunlight is required

Testing #3: 

In this last attempt, I moved to another place with the most intense and direct sunlight and the car still didn’t move, and I thought of many possibilities including why: ex. Not enough sunlight? Sunlight is not direct? Something went wrong with the gears? the motor doesn’t work? or the solar panel is broken?

Problem 1: I realized that when I turn the solar panel perpendicular to the sun, the gears start to turn, and I realized that this is because there is direct sunlight shining on all of the solar panel cells. When the car is parallel to the ground, the sun is shining only on the front half of the solar panel, which is not enough energy to power this car.

Problem 2: I also realized that the gears do not touch either unless the car is placed on the ground so I will need to also fix that

Changes to make/feedback:

  • I asked many of my peers for feedback for the best way to fix this problem
    • Feedback 1: tilt the solar panel to a leat a 45-degree angle or more = more sunlight captured
    • Feedback 2: find a way to secure the metal rod so that the gears can touch at all times
    • Feedback 3: Switch the base material to something hard and unbendable
    • I thought that feedback 1 would be the most effective solution, that would take a lesser amount of time compared to the other ones
  • Change the object supporting the solar panel so that it can allow the solar panel to tilt at an angle

Last working class/block 5:

After Improvement: 

Changes the supporting object and cut it to an angle so that the solar panel will be placed at an angle

                 *After placing the solar panel

Testing #4:

This video shows me testing out the final product after making the changes and seeing what improvements I still need to make…

I needed to face the car directly (perpendicularly) at the sun so that sunlight charges to all the cells and then turn the gear lightly with my fingers just to ‘get it going’ (start spinning)

Problem 3:

Then I discovered another problem which is how the gears don’t touch when there isn’t any weight applied to it… for the two gears to piece together, the car needs to stay on the ground so that the weight of the car and materials will bend the cardboard a bit so the gears perfectly match together. BUT when I lift the car up, the weight is removed therefore, the gears don’t touch which leads to the wheels not spinning.

In order to solve this problem, I tried the following three strategies:

In the above video, I tried to place it on a slanted surface to see if it would work that way but it still did not

I also tried to place it slowly as possible on the flat surface to see if that would help with not decreasing the level of sunlight that is received, but as you can see when the car is flat on the floor, the motor stops spinning.


Lastly, I went to fix the gears to see if there is a way that I can fix this problem, and I came up with two solutions:

  1. Fix the straw that is holding the metal rod so that the rod is not loose and stays in contact with the other gear at all times
  2. Change the base (cardboard) to plastic/wood; something hard and not able to bend

I figured that the last solution would be too complicated and unable to manage since I would need to take apart the whole thing and reassemble it, and this is the last working class so that solution wasn’t reasonable. So, I choose strategy 1

In the above video, I changed the plastic thick straw to a clear straw that is much thinner, so that the metal rod has lesser room to move around/ therefore the metal rod should be more stable

This video shows what it looks like after I changed the plastic straw

Engineering Project – Develop and Plan

1. Make a plan for time and check/bring materials


  1. Wednesday: finish designing and refine designs/ consider all the materials needed
  2. Friday: start building and continuously testing along the way (take videos and photos)
  3. Saturday: testing and building & refining the device
  4. Tuesday: ordering any materials that are still required and record process & plan
  5. Wednesday: Finish the product and give it to three people at least for review and advice
  6. Thursday: Change and improve according to the feedback & final adjustments

Materials NEEDED:

  • solar panel (3v or 6v)
  • wheels
  • a DC motor
  • Wires x2
  • hot glue gun
  • cardboard

2. EMBED Models (annotated sketches)

WechatIMG55 1