Department of Geography, The University of Hull
SOLAR POWER FROM THE EQUATOR TO THE POLES
Jh\verbatim\university\modules\renewable energy\practicals\solar power for schools
Figure 1.
Solar power is measured in Watts/square meter (W/m2) and varies from about
300 W/m2 at the equator (0o) to about 50 W/m2 at the north and south poles
(90o).(From http://www.ez2c.de/ml/solar_land_area/ Ctrl click the image to
follow the link.
Solar Power is one of the most direct Renewable Energies. Solar Power
systems convert the energy of the Sun into electricity. In our experiment we are
going to measure how the solar power varies from the equator to the poles.
In our experiment, the Sun is overhead at the equator. This occurs on 21 st
September as the Sun travels south and 21 st March as the Sun travels north.
These days are called the ‘equinoxes’ because there are twelve hours of
darkness and twelve hours of daylight everywhere.
We measure distances from the equator in degrees of Latitude, so that 0o
represents the equator and 90o represents the poles. Our experiment measures
the solar power from the South Pole to the North Pole
We measure distances from the Greenwich Meridian in degrees of Longitude.
Our experiment measures the solar power along the Greenwich Meridian.
Object
To determine how solar power changes from the equator to the
poles.
Latitude
Theory
The solar power at the earth’s surface decreases linearly (in a
straight line) from the equator to the poles.
Method
1. Set up the globe for equinoctial conditions (Sun overhead the
Equator) with the Greenwich meridian towards the light source.
2. Measure the solar cell output to the North of the equator:
(i)
(ii)
(iii)
(iv)
(v)
On the geographical equator (Oo)
On the Tropic of Cancer (24oN)
On the latitude of the University (54oN)
On the Arctic Circle (66oN)
At the North Pole (90oN)
3. Repeat the experiment working south from the equator:
(i)
(ii)
(iii)
(iv)
On the geographical equator (Oo)
On the Tropic of Capricorn (24oS)
On the Antarctic Circle (66oS)
At the South Pole (90oS)
Results
Complete the table on the following sheet
Analysis
1. Plot the data from the poles to the equator on the graph
2. Comment on your results and, in particular, is the theory
correct?
Students Name ...........................................................
Latitude
0
24 N
54 N
66 N
90 N
Equator
Tropic of Cancer
University
Arctic Circle
North Pole
Equator
Tropic of Capricorn
Arctic Circle
South Pole
Meter Reading
0
24 S
66 S
90 S
200
Meter
Reading
150
100
50
0
90S
50S
Describe your results:
0
Latitude
50N
90N
Teachers’ Notes
The experiment is easy to set up and consists of:
1. Standard globe, available from e.g. Philips etc.
2. Table lamp (the Sun) (low voltage is preferable for safety reasons).
3. Small solar cell, available from e.g. Maplin
4. Voltmeter to measure output from solar cell, again e.g. Maplin
5. Small strips of sticky backed velcro
Set up the Sun at a suitable distance from the globe
Set up the globe so that the equator is facing the Sun (this may require a clamp)
Stick the Velcro at the latitudes given in the instructions above
Connect the solar cell to the voltmeter
Then proceed as in the instructions
Any problems, email me at j.hardisty@hull.ac.uk
Good luck and have fun, our group of 10 year olds did!
© J.Hardisty 2010