Solar Model Cars
Bill Kuhl
http://www.scienceguy.org
Looking for more science projects on the Internet, I 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.
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.
(A)– first car I built from Tamiya components I found in local hobby shop. (B) – second car built using solar panel
and motor specified in Junior Solar Sprint rules. (C) – Sun Zoom Lite car kit was the third car I built which is an
inexpensive kit.
Applications for photovoltaic solar panels – (A) large solar panel seen at the Minnesota State Fair was available
for rent. (B) - calculator powered by small solar panel. (C) – traffic signals sometimes use solar panel to charge
battery power. (D) – small solar panel recharges battery in garden light.
Electric Motors (A)- demonstration electric motor leaves everything exposed to show how motor operates.
(B) – close-up of brushes and commutator in demonstration motor. (C) – commutator and windings seen in
Speed 400, a typical brushed electric motor.
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.
(A) – Tamiya .5 volt 1200 mah solar panel (B) – Tamiya 1.5 volt 400 mah solar panel (C) - Tamiya motor designed
for solar panels. (D) – two types of lightweight model airplane wheels I considered using. (E) – the chassis of the
car was constructed of thin plywood, brass eyelets were sandwiched between balsa for bearings.
(A) – motor has been mounted on the chassis, spur gear was from radio control car. (B) – chassis has been
flipped over, music wire is used for axles, craft beads were used for spacers next to wheels. (C) – the solar panel
came with adjustable mount. (D) – thin plywood shims were put under the motor because the gears were
meshing too tightly.
(A) – panel specified for Junior Solar Sprint is rated at 3.5 volts @ 3 watts (B) – this is the motor specified for
Junior Solar Sprint (C) – I also ordered wheels, axles, and gears from Solar World (D) – craft beads I used for
spacers (E) – bamboo skewers were used to strengthen the chassis of the car.
(A) – brass eyelet worked well for bearing. (B) – underside of rear half of car shows reinforcement done with
plywood and bamboo. (C) – electric motor ran smooth with the gears provided. (D) – after seeing the pivot on
the Tamiya panel, I built my own swivel joint using a ping pong ball.
(A) – Pitsco solar car kits can be purchased in an economical 10 pack. (B) – top side of the small solar panel.
(C) – seen from the back, the solar panel is only .45 volt 400mah (D) – I measured the voltage of the panel at .47
volt in strong sun.
(A) – screw eyes make for an easy to install bearing. (B) – side view of front axle and wheels. (C) – gear font
gave the specs of all the gears included, more gears than needed but might be useful for another project.
(D) – large assortment of gears included.
(A) – using 20-tooth pinion and 40-tooth spur gear specified in instructions, the car would only move under ideal
conditions. (B) – with 10-tooth pinion the gears would not mesh with motor on top of chassis. (C) – I flipped the
car over and tried placing the motor in the rear but panel could not rest on top of the motor. (D) – moving the
motor ahead of the rear wheels should work.
Consider These Fun / Educational Activities Also:
Model Airplanes