Solar Energy (Solar Heating)

 Introduction: 

Solar Energy or Solar Heating project is a collection of science experiments you can use as a science project for your upcoming science fair. This project is simple, quick and very educational. The experiments on this project will help you observe how concave/ converging mirrors collect and concentrate the solar radiations in one small point. You will also learn how different colors affect the amount of heat an object may absorb from the sunlight. Most experiments in this project have measurable results that can be used to create a data table and a graph. The experiments for this project may be performed outdoor in a sunny location or indoor if sunlight is entering trough a clear glass window. We recommend indoor experiments if the weather is cold or windy.

Materials:

This solar energy (Solar Heating) science set contains the following:

  • Wooden stand with a 16" wooden rod
  • Glass thermometer (Basic Laboratory Grade*)
  • Concave/ converging Mirror
  • 5 Plastic Test Tube

*Note: You cannot use a medical thermometer for this project.

Additional Materials you will need include:

  • Food coloring or color paper
  • Watch, clock or timer
  • Paper and pen to record your results
  • Sunlight

WARNING: Adult supervision and support is required for all experiments and for handling the materials. Do not leave your experiment setup unattended.

How to use a thermometer?

The thermometer has a red bulb filled with red liquid and a narrow column of red liquid above that. The level of liquid in the narrow tube shows the temperature. To measure the temperature, the bulb of the thermometer must be inserted in the space or the liquid you want to measure its temperature. Changes are fairly quick. About 5 seconds after the movement of the red column stops, you can record the temperature.

List of Experiments:

  1. Efficiency of solar heaters
  2. Solar energy in different times of the day
  3. Effect of color in absorbing solar energy
Experiment 1: Efficiency of solar heaters

Introduction: In a solar heater we use reflectors to concentrate the solar energy in one small point where we want to cook something or collect and store the heat energy. In this experiment we want to see how efficient a solar energy collector is. To do this we will compare the natural heat of sunlight with the heat collected by a solar heater.

Procedure:

  1. Mount the wooden rod on the stand
  2. Cut three pieces of 3" x 3" black paper and roll them around a pencil and then insert each rolled paper in one test tube. (You use the black paper or black color because other experiments have shown that black color will absorb the most heat from the sunlight)
  3. Use two rubber bands or tape to attach one of the blackened test tubes (without cap) to the middle of the wooden rod. Place the stand in a sunny spot and use the concave side of the mirror to reflect the sunlight toward the lower/ blackened part of the test tube on the rod. Make sure the light is focused on the test tube. Secure the mirror in that position so that it will stay focusing. Readjust it every 5 minutes if needed.
  4. Use two rubber bands or tape to attach the second blackened test tubes (without cap) to the outside wall of a cup or a similar object so that the test tube can stand vertically. Keep this test tube in the shade.
  5. Use two rubber bands or tape to attach the second blackened test tubes (without cap) to the outside wall of a cup or a similar object so that the test tube can stand vertically. Keep this test tube in a sunny spot.
  6. fill each test tube up to 1/2 with tap water.
  7. After 30 minutes record the temperature of all 3 test tubes and record your results. Your data table may look like this:
Location/ Energy source Temperature
Shade 20C
Direct Sunlight 25C
Sunlight collected by converging mirror 68C

You can later use your data in the above table to calculate the ratio of solar energy collected with or without the converging mirror.

To calculate the efficiency of your solar heater with converging mirror you can divide the temperature increase by the temperature increase in direct sunlight. To show you an example we have entered some sample data in the table. (Sample data are not reliable). 

Location/ Energy source Temperature Temperature
Increase
Ratio/ Efficiency
Shade 20C 0C  
Direct Sunlight 25C 5C 1
Sunlight collected by converging mirror 68C 48C 9.6
Based on the above sample data, the temperature increase in direct sunlight is 5 degrees Celsius, while the temperature increase with converging mirror is 48 Celsius. We divide 48 by 5 and get 9.6 as the efficiency of our solar collector with converging mirror. This simply means that your converging mirror can increase the collected energy 9.6 times in compare to direct sunlight.

Diagram in the right shows how parallel sun rays converge into a small hot spot.

 

Make a graph:

You can use a bar graph to present your results. Make one vertical bar for each of the three test tubes. The height of each bar will represent the maximum temperature in each test tube. For example you may make a bar that is 20 mm tall to represent 20 Celsius temperature.

             
             
             
             
             
             
             
             
             
             
             
             
          Shade            Direct
Sunlight
          Converged
Sunlight
          

Experiment 2: Solar energy in different times of the day

Introduction: The angle of the sun changes in different times of the day. Other factors such as cloud may also affect the amount of solar energy we collect each day. In this experiment you will study the changes in solar energy in different times of the day. This will help you know what hours of the day you can collect the highest amount of solar energy. If the weather is cold or windy, you must perform your experiment indoor in a glass house/ greenhouse.

Procedure:

  1. Start your experiment in the morning (after sunrise). Mount the wooden rod on the stand
  2. Cut one piece of 3" x 3" black paper and roll it around a pencil and then insert it in one test tube. (You use the black paper or black color because other experiments have shown that black color will absorb the most heat from the sunlight)
  3. Use two rubber bands or tape to attach the test tube (without cap) to the middle of the wooden rod. Place the stand in a sunny spot and use the concave side of the mirror to reflect the sunlight toward the lower/ blackened part of the test tube on the rod. Make sure the light is focused on the test tube. Secure the mirror in that position so that it will stay focusing. Readjust it every 5 minutes if needed.
  4. Record the temperature of water every 30 minutes.
  5. Measure and record the temperature of water in the test tube every 30 minutes and continue your observations until the late afternoon (sunset).
Time 6 7 8 9 10 11 12 1 2 3 4 5 6
Temperature                          

You can also use the above data table to draw a bar graph.


Experiment 3: Effect of color in absorbing solar energy

Introduction: The color of a substance certainly affect the amount of heat energy an object receives from the sunlight. That is why in winter we wear dark clothes and in summer we put on light color clothes. We are wondering how effective is the color in absorbing energy and what is the best color for a solar energy collector. In this experiment you will make at least one trial for each color.

Procedure:

  1. Get pieces of 3" x 3" papers in black, white, red, blue and yellow papers.

  2. Roll each paper around a pencil and then insert them in one test tube.

  3. Fill each test tubes with tap water up to the 4" level.

  4. Secure all five test tubes to the side of a box using tape or rubber band.

  5. Place the box in a sunny spot (preferably indoor) so that all test tubes will receive the same amount of sunlight.

  6. Measure and record the initial temperature of all five test tubes.

  7. Watch your setup and make sure that all test tubes are getting sunlight for one hour. Reposition the box as needed as the sunlight moves.

  8. Measure and record the temperature of all five test tubes after one hour.

  9. Record the initial temperature, final temperature, and calculate the temperature increase in each test tube and enter them in your data/ results table.

Color Initial Temperature Final Temperature Temperature increase
Black      
White      
Blue      
Red      
Yellow      

Make a graph:

Use a bar graph to present your result. Make one vertical bar for each color. The height of each bar will represent the temperature increase in the test tube with that specific color.

 

If you don't have this kit, you can order it now! It is available both as a single pack and class pack.