The RESULTS can be found in the table below:
Panel number
Tilt (angle with the
horizontal plane)
Total annual energy-output of the panel
(kWh/year)
1
234569
0°
10°
20°
30°
40°
50°
90°
350
370
390
410
385
360
220
Draw a bar graph to illustrate the annual energy-output at different tilt angles for
the seven solar panels.
4.1.1 Which tilt angle gives the highest annual energy-output?
4.2 Which factors were kept constant (which variables were controlled) during this experiment?
4.3 Identity the independent variable in this experiment.
4.4 "In summertime the sun sits high above the horizon in the sky." Use this statement and explain why a fixed tilt angle of 90 degrees produced such a low energy - output value. You can make use of a labelled sketch to explain your answer.

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