: Interactions of energy and matter
Standard E, Science and Technology: Understandings about science and technology
Overview: In this activity, students will discover the basic principles behind solar power and
electronics. Much graphing is required for this activity, so knowledge of graphing is required.
The teacher may choose to have the students use a graphing program such as Excel to complete
their graphs.
Purpose: The purpose of this activity is to allow students to explore the basic ideas behind solar
power, including electronics, solar panels, position of the sun, position and tilt angle of the
modules, and shading of the module. Through exploration, the students should gain a better
understanding of these principles and how they contribute to solar power.
Learning Objectives: By the completion of this activity, students should be able:
To work a multimeter to measure voltage and current
To determine the position and tilt angle for the module to produce the highest power at a
given time
To explain how voltage, current, and power change with different tilt angles on the
module
To explain how voltage and current affect power
To explain how position and tilt angle affect the power output of a module
To explain how shading affects the power output of a module
To determine if cells are connected in series or parallel
To explain differences between class results for best tilt angle and position in relation to
the changing position of the sun
To predict solar noon
Vocabulary: Before the beginning of this activity, students should have a basic knowledge of
the following words:
solar power
current
voltage
power
series connection
parallel connection Resources and Materials:
small PV modules and a multimeter for each module (number depends on class size and how
many you wish to place in a group), protractors, calculators, compass, Excel or other graphing
program (not necessary, but helpful), and a sunny day!
Preparatory Activities: Prior to this activity, students should know:
The difference between a series and parallel connection, that in a series connection the
voltages are added and in a parallel connection the currents are added
The very basics of how a solar panel works (the basics of how it converts sunlight to
energy), and the difference between a cell and a panel. Although not much knowledge of
solar energy is necessary for this lab, the teacher may desire to spend a day prior to this
activity introducing solar energy and discussing some of the advantages and
disadvantages of its use.
Knowledge of Excel or some other graphing software program is helpful to complete this
activity since a large amount of graphing is required. However, the teacher may choose
not to use such software based on the ability of the students and the available resources.
Students can make the graphs manually in place of the graphing software. Most
importantly, students need to have a good background in graphing.
Main Activities:
Note: The following schedule of events is merely a suggestion. The teacher for this activity
should allot time according to the needs of his/her class based on class period time and the
students' knowledge. The suggested schedule assumes 2 ninety-minute block periods. But, this
lesson can be broken into several segments if needed. It is important to note, however, that the
measurements for Parts 2 and 3 should be made on the same day.
Day One: Introduction and Measurements
The students should be broken into groups of 3 or 4 based on class size and number of
supplies. Each group needs one PV module, a multimeter, a compass, and a protractor. (5
minutes).
Assuming the students have not used a multimeter prior to this lab, the teacher should run
a practice session, demonstrating how to use the multimeter to measure both current and
voltage. Each group should practice these measurements inside the classroom before
making measurements outside. (20 minutes).
Once each group has demonstrated the ability to measure current and voltage with the
multimeter, the class should move outside to make their experimental measurements (5
minutes).
The students will make their measurements for Parts 2, 3, and 4. The students should
write the procedures and required hypothesis in their lab notebooks, along with
corresponding data tables and answers to questions. The students should not work on any
of the italicized instruction or questions until they have completed their measurements for
Parts 2, 3, and 4. (55 minutes).
The class will return back to the classroom and return supplies to their proper place. (5
minutes). Day Two: Analysis of Lab
The students should work individually on the analysis of this lab, especially for Parts 2, 3,
and 4. The whole class period should be dedicated to allow students to work on the
italicized portions of the lab that they did not work on the previous day. The analysis
requires a large amount of graphing and access to Excel or another graphing software
would be helpful. However, the teacher may request that the students do their graphing
manually. (90 minutes)
About 15 minutes before the end of class, the students should have all written down their
answer from question #5, Part 3 on the board. At this point in time, the class should
discuss and devise a method for determining the overall class result for the best position
and tilt angle of the PV module.
Students should finish Part 5 for homework.
Note to teacher: This lab should be "de-briefed" the next day in class. At this time, the teacher
should allow about 15 minutes for a class discussion on the most important findings of the lab,
and to address any issues that might be confusing for the students. This de-briefing period is
essential to helping students' tie information together and this time should not be overlooked! Name:___________________________________________________________
EXPLORING SOLAR POWER
In this activity we will discover the basic principles behind solar power and electronics. Please note
that any italicized writing refers to analysis activities that are best done after the collection of all
of your data. For instance, your teacher may require you to collect data for all five parts before
you begin actually interpreting this data.
Part One: Setting up the Photovoltaics and Multimeter
Draw a picture in your lab notebook that shows how you have connected your module to your
multimeter. Don't forget to include positive (red) and negative (black) connections. Also, make
sure to label you're drawing!
Part Two: Tilt Angle
How do voltage, current, and power change in relation to the angles of the module? How are
voltage, current, and power related?
Before you begin this experiment, be sure to write a 1-2 sentence summary of the procedure and
make a data table in your notebook to record voltage, current, and power for each angle being
measured. You do not need to write a hypothesis for this portion of the experiment.
Use a leveler to create a surface where the PV module can lie completely horizontal. This will be a
0º angle. Measure current and voltage with the multimeter at this angle. Using a protractor, adjust
the PV module so that it is tilted 22.5º from horizontal. Measure and record the corresponding
voltage and current at this angle. Perform the same procedure for 45º, 67.5º, and 90º. Be sure to
note the time in your notebook.
1. Calculate the power for each angle. At which angle listed above does the PV module produce
the highest power?
Devise a test to determine the angle at which the PV module can produce the highest power (at this
time, on this day). Write the procedure for this test in your lab notebook, write your hypothesis,
and then perform your experiment. Again, be sure to record the time in your notebook.
2. According to your data, at which angle does the PV module produce the highest power? Be
sure to note the time of day and date in your answer! (Ex. At 10:15 am on Oct. 14, 2001, the
PV module produced a maximum power of _____).
Use Excel to plot the angle vs. voltage, current, and power. You should create three separate graphs in order to
properly plot this information. Also, make all of the graphs the same size so that you can compare among the graphs
easily. Be sure to include all of the data you acquired to answer #1 and at least some of the data acquired to answer
#2. 3. Based on the graphs you created, can you define any relationship between angle and the three dependent
variables (voltage, current, and power)? If so, what? Explain.
4. Based on the 3 graphs, did current or voltage have a greater affect on your calculations for power? How do
you know?
5. Write a conclusion for this part of the lab that is about 5 sentences long. Do not forget to compare your
hypothesis to your results!
Part Three: Positions
How do voltage, current, and power change in relation to the position of the module?
This part of our investigation is very similar to that in Part Two, except that in this part we will be
changing the angles that the module is positioned instead of the tilt angle.
Here, you are required to measure current and voltage at the following positions: 0º, 45º, 90º,
135º, 180º, 225º, 270º, and 315º. You can measure the degrees of position by using a compass,
where 0º represents magnetic north. Also, you should be sure to use a tilt angle close to the one
that gave you maximum power in Part Two. Be sure to write a procedure for this experiment,
record the time of day, perform the experiment, and record y