Solar Panel Investigation

Background Knowledge

. Solar cells convert visible light into electricity. Just now they are expensive to produce and have poor efficiency but for some applications they are unbeatable. Satellites rely on panels of solar cells to generate electrical power. Research on solar cells is directed towards finding a new manufacturing process, which will reduce costs and boost efficiency.

Prediction.

It can be considered that as the distance is changed, so the voltage will be altered as well. As the panel is moved further back away form the light, less light will hit the panel so less voltage will be generated. The inverse square law can explain this further. It is explained below:

C

3d

B

2d

A

d

X

B is 2 times the distance of A therefore according the inverse square rule the light intensity at point B will be the inverse square of the light intensity at point A. Therefore if the light intensity at point A is 1 then at point B it will be the inverse square of 2 (because that is the 2 times the distance of A) so the intensity will be 1/4 and for point C the light intensity will be 1/9 (because that

Is the inverse square of 3 which is the times distance of A).

This law shows how distance affects the light intensity on the solar panel. As you get further away, the light from the bulb gets more spread out meaning that less of it hits the solar panel.

I would therefore expect the graph for our results to look like this:

Method.

We will do our experiment in the following way:

2. Set up apparatus as in shown in the diagram

3. Once all the other groups have begun work place the solar panel in the middle of the paper and take a reading for the background light.

4. Place the panel directly in front of the light making sure that it is horizontal and perfectly straight before taking a measurement for the voltage at 0cm.and fill in the table.

5. Move the solar panel back 10cm checking accurately using the metre ruler running parallel to the black paper. Record the voltage and fill in the table.

6. Repeat step 4 until we have results for 0cm - 1 metre.

7. Once these results have been acquired repeat steps 3,4,5 twice more to get a second and third sets of results.

With the results find a mean average for each distance so that they can then be plotted on a graph.

Results

Distance (in cm)

Voltmeter reading (in volts)

Voltmeter reading 2 (in volts)

Voltmeter reading 3 (in volts)

Average reading (in volts)

0

4.15

4.09

4.12

4.12

0

3.24

3.27

3.26

3.26(2dp)

20

2.47

2.45

2.39

2.44

30

.90

.90

.83

.88

40

.49

.47

.43

.46

50

.20

.22

.16

.19

60

.00

.02

0.97

.00

70

0.87

0.87

0.83

0.86

80

0.73

0.76

0.77

0.75

90

0.67

0.68

0.65

0.67

00

0.34

0.64

0.60

0.53

To make sure the results were as accurate as possible we measured the voltage output of the solar panel three times for each distance, which allowed us to identify any anomalous results, which failed to fit the pattern that the others followed.

We only came across one measurement that didn't clearly fit the pattern, this was the first reading for the 100cm distance which was about half of what we had expected to see.

Graph

Analysis

During our investigation it was found that when we directed the bulb at the solar panel the light energy was converted to electrical energy. This was shown on the voltmeter, which showed how much light had been converted to electrical energy at each distance.

From the graphs shown below you can see that the data has a strong negative correlation that shows that as the distance increases the voltage decreases. This is just as we had foreseen in the prediction.

This investigation shows that as the distance from the light source increases, due to the fact that there is less light hitting the solar panel that could be converted into electricity, effectiveness of the solar panel to convert the light to electricity decreases. This is because less light hits the panel and the rays are less concentrated and more spread out over a greater distance. The inverse square law explains this in greater detail, and was mentioned previously. The results of our investigation match my prediction well, which proves that the theory behind it was correct. The only result that was incorrect was the first reading at 1 metre, which could have been caused by a number of reasons. Firstly background light was present in different amounts at each stage of the experiment, which could have meant that our result was affected by other groups' experiments. But also we may have rushed the experiment and not taken the time to let the voltmeter settle on the correct voltage, as it has a tendency to fluctuate across a range of values before stopping.

Evaluation

The experiment was conducted well and we managed to get a set of fairly accurate results from which we were able to draw reliable conclusions. But our experiment was flawed and could have been improved. Since there was more than just our group working in the room we really could have done with working alone in another separate room without any other interference from the lights of other groups. This would mean that there would be no background light and the results would be much more accurate. Another improvement we could have made would have been to use a more accurate voltmeter to measure the voltage to a greater degree of accuracy, and to increase the amount of readings taken at each interval, or even decrease the intervals to every 5cm.

To extend this investigation further, we could use a different variable to the distance, instead, changing the light intensity of the bulb or the angle at which the light hits the solar panel.

Overall the investigation went well, and we feel that the results we got were accurate enough for us to draw conclusions and prove the prediction correct.