2 BackgroundLooking for more science projects on the Internet, I ran across ran across the Junior Solar Sprint Competition. I have been interested in alternative energy for a long time, so I decided I would build a solar powered model car.EverythingHobby had two Tamiya solar panels and one motor. I purchased the motor and the ½ volt 1200 mah panel to start with thinking both panels were the same. I later purchased the other panel which was 1.5 volts 400 mah, this would be good for experimenting with trade-offs between voltage and amperage.
3 For my next car I purchased the panel and motor specified for the Junior Solar Sprint Competition, in my first tests of running this car pictured above, the speed is at a jogging speed. This car was also an experiment in using bamboo to stiffen the thin plywood chassis.I also purchased a 10-pack of kit cars from Pitsco because the price is below $10 a car and I thought this would be good for a class this summer. The solar cell is rather tiny so I used lower gearing to get the car to move, but it will work fine in bright sun.The model solar cars appear to be a good activity to learn about harnessing sunlight, electricity, electric motors, gearing, and construction ideas.
4 The first car I built from Tamiya components I found in local hobby shop.
5 The second car built using solar panel and motor specified in Junior Solar Sprint rules.
6 Sun Zoon Lite car kit was the third car I built which is an inexpensive kit.
7 Applications for Photovoltaic Solar Power This large solar panel seen at the Minnesota State Fair was available for rent.
8 Another smaller solar panel seen at Minnesota State Fair
13 Demonstrating Small Electric Motors This demonstration electric motor leaves everything exposed to show how motor operates.
14 Close-up of brushes and commutator in demonstration motor.
15 Commutator and windings seen in Speed 400, a typical brushed electric motor. Note: When looking for a motor for solar power, it helps to look at the start-up current requirements as some motors require more electricity to start than others.
41 Chassis turned upside down before I put layer of balsa on top of eyelets which completes the balsa sandwich.
42 Motor running, gears must mesh easily for good performance. The correct gearing is a trade off between quick enough acceleration and top speed. Small gear on motor shaft is the “pinion” and large gear is the “spur” gear.
43 Solar panel in the horizontal position, adjusting the panel to match the angle of the sun will make a big difference in performance.
44 Ping pong ball used for swivel Ping pong ball used for swivel. Straps were made plastic in a cottage cheese container.
46 The underside of rear half of car shows reinforcement done with plywood and bamboo.
47 After seeing the pivot on the Tamiya panel, I built my own swivel joint using a ping pong ball.
48 Platform for panel made from Popsicle sticks and thin plywood Platform for panel made from Popsicle sticks and thin plywood. Velcro fastens the panel to the platform, the panel could easily be switched to another car. I like to design everything to be flexible if possible.
49 Pitsco SunZoon LiteI ordered the 10 pack of solar cars from Pitsco which are very reasonably priced. The car goes together easily but needs very bright sun to move the car.
50 Pitsco SunZoon Lite kits are available in a 10-pack.
57 Gear font gave the specs of all the gears included, more gears than needed are included but might be useful for another project.
58 Many gears are included but some are larger in diameter than the wheels which is a problem.
59 I installed the 20-tooth pinion gear per the instructions but the car would only move in really bright sunlight. With the PV panel putting out less than ½ volt there is no power to spare. Spur gear 40-tooth.