How different angles of incidence of solar rays impact the performance of a solar cell.Featured science projectScience project video

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Complexity level:
5
Project cost ($):
60
Time required:
1 day to prepare, 1 hour for experiment
Material availability:
Safety concerns:

Exercise caution when sawing wooden blocks. Long hours of exposure to the sun may cause dizziness, dehydration or heat stroke. Make sure you drink an adequate amount of water and put on sunscreen. You should ensure that you protect yourself with an umbrella or wear a hat as you will be under the sun for a fair amount of time.

Abstract

This experiment was done to find out how changing the angle of incidence of sunlight throughout the day impacts the efficiency of a solar cell.

Hypothesis

The power output generated by a solar cell will be highest when the solar cell is positioned perpendicular to the direction of sunlight.

Background

Solar cells

Solar cells are used to convert energy from the sun into electrical energy which can be immediately used or stored in a battery for later use. They are made from silicon which is found in abundance on our planet. However the cost of converting raw silicon into useful solar cells is very expensive. Currently, there are 3 types of solar cells which are commonly used:

Monocrystalline solar cells have a good level of efficiency of between 14% - 18% of energy conversion, but these solar cells are expensive.

Polycrystalline solar cells are a cheaper alternative, but these have a lower efficiency rate of conversion of between 11% - 13%.

Amorphous solar cells are another cheaper alternative; however, these have the lowest energy conversion rate of between 8% - 10%.

Because solar cells are very expensive, it is necessary to optimize their performance to obtain a quick return on investment. This is why solar trackers are useful in enabling solar panels to work at high efficiency throughout the day.

Solar tracker

The rotation of our planet causes the sun to rise in the east and set in the west. From sunrise to sunset, the sun travels 180 degrees across the horizon. Since solar cells produce maximum output when the panels are placed perpendicular to the sun position, the solar tracker is a motorized device, which adjusts the disposition of the solar panel to follow or"track" the angle of incidence of sunlight throughout the day. This allows the solar panel to work at full efficiency at all times during the day.

Scientific Terms

Solar cell, photovoltaic cell, solar tracker, monocrystalline cells, polycrystalline cells, amorphous cells, ammeter, and voltmeter

Materials

 

The materials required for this experiment:

  • 7 polycrystalline solar cells 0.5V 2.0A, 1Watt
  • 7 wooden cubes (their lengths should be the same as the solar cells)
  • 1 saw
  • A protractor
  • 1 roll of double-sided tape
  • 1 digital voltmeter
  • 1 ammeter
  • 1 resistor (0.25 ohm 4 watt)

 

Procedure

1. For this experiment, the independent variable is the angle of the solar cell. The dependent variable is the power output from the solar cell. This is determined by measuring the voltage and current produced. The constants (control variables) are the resistor, amount of sunlight, the temperature and the type of solar panel used.

2. The wooden blocks are cut with a saw in the workshop as shown in figure 1. The angles given below the drawings are measured using a protractor between the vertical line and the surface onto which the solar cell will be mounted.

3. This experiment is conducted outdoors at noon (1200 hours) when the sun is directly overhead on a clear day.


4. The solar cells are mounted onto the wooden blocks using double sided tape as shown in figure 1. The voltmeter (V) and ammeter (A) are connected as shown in figure 2. The voltage and ampere readings are taken and recorded in the table below.

5. The procedure 4 described above is done on all 7 solar cells mounted at different angles. The voltage and ampere readings are taken and recorded in the table below.
The output power of the solar cell is calculated as follows:

Power (watt) oltage (Volt) x Current (ampere)

Observation

The results show that the solar cell mounted perpendicular to the sunlight has the highest power output and this output continues to decline as the angle reduces to zero.

Use the below graph to plot the results in the above table.

Conclusion

The hypothesis is proven to be correct. The power output generated by solar cells will be at its highest when the solar cells are positioned perpendicular to the direction of sunlight.

The use of a solar tracker will help the solar panel follow the path of the sun and this allows the solar panel to remain perpendicular to the angle of incidence of the sun's rays, for maximum efficiency and power output. 

Also consider

Try to repeat the experiment using amorphous solar cells.

Try to simulate real life as much as possible. Introduce elements such as wind, water (rain) and ice to the test environment. How do the results differ? Will your results differ on a cloudy day?

References

  • Solar mirror - http://en.wikipedia.org/wiki/Solar_mirror
  • How do solar panels work - http://www.glrea.org/articles/howDoSolarPanelsWork.html

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