BackgroundLooking for more science projects on the Internet, I ran across ran acrossthe Junior Solar Sprint Competition. I have been interested in alternativeenergy for a long time, so I decided I would build a solar powered modelcar.EverythingHobby had two Tamiya solar panels and one motor. I purchasedthe motor and the ½ volt 1200 mah panel to start with thinking both panelswere the same. I later purchased the other panel which was 1.5 volts400 mah, this would be good for experimenting with trade-offs betweenvoltage and amperage.
For my next car I purchased the panel and motor specified for theJunior Solar Sprint Competition, in my first tests of running this car picturedabove, the speed is at a jogging speed. This car was also an experiment inusing 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 solarcell is rather tiny so I used lower gearing to get the car to move, but it will workfine in bright sun.The model solar cars appear to be a good activity to learn about harnessingsunlight, electricity, electric motors, gearing, and construction ideas.
The first car I built from Tamiya components I found in localhobby shop.
The second car built using solar panel and motor specified inJunior Solar Sprint rules.
Sun Zoon Lite car kit was the third car I built which is aninexpensive kit.
Applications for Photovoltaic Solar PowerThis large solar panel seen at the Minnesota State Fair was availablefor rent.
Another smaller solar panel seen at Minnesota State Fair
Demonstrating Small Electric MotorsThis demonstration electric motor leaves everything exposed to showhow motor operates.
Close-up of brushes and commutator in demonstration motor.
Commutator and windings seen in Speed 400, a typical brushed electricmotor. Note: When looking for a motor for solar power, it helps to look atthe start-up current requirements as some motors require more electricityto start than others.
Chassis turned upside down before I put layer of balsa on top of eyeletswhich completes the balsa sandwich.
Motor running, gears must mesh easily for good performance.The correct gearing is a trade off between quick enough acceleration andtop speed. Small gear on motor shaft is the “pinion” and large gear is the“spur” gear.
Solar panel in the horizontal position, adjusting the panel to match theangle of the sun will make a big difference in performance.
Ping pong ball used for swivel. Straps were made plastic in a cottagecheese container.
The underside of rear half of car shows reinforcement done withplywood and bamboo.
After seeing the pivot on the Tamiya panel, I built my own swiveljoint using a ping pong ball.
Platform for panel made from Popsicle sticks and thin plywood. Velcrofastens the panel to the platform, the panel could easily be switched toanother car. I like to design everything to be flexible if possible.
Pitsco SunZoon LiteI ordered the 10 pack of solar cars from Pitsco which are veryreasonably priced. The car goes together easily but needs very brightsun to move the car.
Pitsco SunZoon Lite kits are available in a 10-pack.
Gear font gave the specs of all the gears included, more gears thanneeded are included but might be useful for another project.
Many gears are included but some are larger in diameter than thewheels which is a problem.
I installed the 20-tooth pinion gear per the instructions but the carwould only move in really bright sunlight. With the PV panel putting outless than ½ volt there is no power to spare. Spur gear 40-tooth.
I installed the smaller 10-tooth pinion gear on the motorshaft but it does not match up with the spur gear, amodification would be needed.
I flipped the car over and considered putting the motor in the rearbut the solar cell could not rest on the motor because the wheelswere in the way.
Moving the motor in front of the spur gear will prop up thesolar panel and gears mesh fine. The gear ratio is now 1:4which gives the car more torque to move.
Completed car, some of the wood chassis could be cut offmaking the car slightly lighter.