Parts List
1 x base plate 1
1 x small sprocket wheel 9
1 x engine shaft 19
1 x black cable 20
1 x red cable 21
1 x battery holder 22
1 x solar module 23
1 x solar engine 24
line and the black one is the negative line. Be sure to
pay attention to the plus and minus symbols on the
battery holder and the engine when you attach the
cables. Then take your model into bright sunlight and
orient the module toward the Sun. What happens?
Results
As soon as enough light falls on the solar module,
the engine will start to turn. Direct sunlight is bright
enough to get your engine going. In shade, it isn’t
bright enough — the engine won’t move. Light and
shadow are like the on-off switch for the solar engine.
The solar cell has the ability to convert light into
electrical current, and it is this electrical current that
drives the engine. The engine stops when not enough
light falls on the solar module. In your house — of-
ten, even right next to the window — the light isn’t
intense enough. The bigger a solar cell is, the more
current it can produce. It also makes a difference how
the solar cell is constructed. On your module, there
are just a few small solar cells that are only capable
of producing a little current. That is why your engine
needs a lot of light in order to turn.
In our first experiment, a small sprocket wheel (9) mounted on the
engine shaft is turned. Mount it so that it sits flush at the front.
Your first solar model turns the small sprocket wheel inserted onto the
engine shaft.
Little Shadows
It would be interesting to know just how much light
your solar module needs in order to run the engine.
Experiment 2
>
You will need: your solar model from the previ-
ous experiment
Instructions
Set your solar model in bright sunlight so that the
engine turns. Next, hold your finger over the solar
cell. Does the sprocket wheel still turn? What happens
when you hold two or more fingers over the solar
module? Try adjusting the distance between your
fingers and the solar module.
Results
When you hold your finger over the solar module, it
creates a small shadow. The shadow in turn darkens
a small part of the surface of the panel in which the
solar cells are located. The rest of the panel still gets
enough light to run the engine. The more of the panel
that you cover in shadow with your fingers or hand,
the less light the solar cells get. When there isn’t
enough light, the engine won’t move.
IMPORTANT NOTE ABOUT LIGHT SOURCES!
Not all light sources produce enough light for the solar cell to
power the motor. We recommend at least a 75 Watt incandescent
bulb in a suitable desk lamp fixture. Fluorescent lights, flashlights,
and low-voltage halogen lights will not work well. Of course, the
Sun is much more powerful than household lamps and should be
used if possible.
9
