3
POWERING A COMPONENT USING THE SOLAR PANEL
In the right light conditions the output from the solar panel is
sufficient to power components such as LEDs, small motors and
LCD displays. For components with a positive and negative
terminal, the red wire from the solar panel must connect to the
positive terminal.
The best type of motor to use with the solar panel is a solar motor
because this type will run with a small current. However, the
MM10, MM12, MM18 and the economy gearboxes will also work
directly from a single solar panel. The illustration below shows a
solar powered buggy that has a solar motorised gearbox.
Instructions explaining how to make the buggy are included at the
end of this pack.
blue
wire
cathode
red
wire
anode
If a larger motor is required, two
or more solar panels may be
connected in parallel to
produce a higher current.
For components that require a
higher voltage, two or more
solar panels may be connected
in series.
6
Investigating the Output of the Solar Panel
Connect a multimeter to the solar panel and adjust it to the 200mV
setting. The meter will display the voltage produced. Try covering
the panel with a hand and observe the drop in voltage. How does
the voltage change in different light conditions? Write your
findings in the table below. In brighter conditions you will need to
switch the meter to the 20V setting.
)
V
m
(
t
u
p
t
u
O
n
o
i
t
i
d
n
o
C
t
h
g
i
L
Bright sunlight
Overcast daylight
Indoor electric light
Indoor fluorescent light
Halogen spotlight
Battery powered torch
Reflectors can be used to increase the amount of light falling on the
solar cell. Mirror card (code: GS6 007) or mirror polystyrene (code:
CS6 004P) are ideal materials for making reflectors - kitchen foil is
an alternative. Different shapes and different positions of the
reflector can be explored; the multimeter will give a clear
indication of which ones work best.
Examination of reflectors in
torches and other lights may be
helpful here. Many such
reflectors have a parabolic
shape, which focuses light
towards a single point.
Investigating the Spectral Response of the Solar Panel
Intensity of the light is one factor that determines the output of the
solar panel, but it is not the only factor. The wavelength of the
light also makes a difference. This can be investigated using, for
example, coloured LEDs or coloured filters. Many types of LED are
available, including UV and infrared, but it is important to select
LEDs of a similar intensity for the investigation. To avoid
inaccuracies due to changes in the background light, it is suggested
that a ‘black box’ be made to house the solar panel and light
source.
Focal point
Parabolic reflector
OFF
V
600
200
A
200µ
20m
V
2000µ
200m
10
600
200
20
2000m
200m
2000k
200k
20k
2000
200
Ω
hFE
10A DC
VΩm
A
COM
TEACHING
RESOURCES
DT-830B
NPN PNP
E
B
C
E
E
C
B
E
solar
panel
light
source
coloured
filter
light
proof
box
