SHPE Jr. Chapter STEM Activity
Watts Up in Solar Energy
Some simple advice:
• Be prepared. Test-drive the activity beforehand.
• Have all the required materials on hand.
• Keep students on track.
• Keep an eye on the clock and follow the time
frame.
• Be flexible and creative.
• Have fun!
Watts Up in Solar Energy
Goal:
Students experiment with a small PV solar panel by adjusting its angle
relative to the sun (or a lamp) and plotting the resulting change in voltage.
They then consider how angle is taken into account with solar panel
location and installation.
Engineering/STEM areas:
Solar engineering, electrical engineering, astronomy
Learning objectives
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Understand the pattern of the sun’s movement through the sky
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Define tilt and orientation in the context of a solar cell
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Grasp how tilt and orientation affect voltage produced by a PV cell,
and how they relate to zenith and azimuth
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Use tilt and orientation information to determine what angle of
installation will produce energy the most efficiently
Watts Up in Solar Energy
Time:
60 mins
Suggested group size:
3-4
Materials:
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Student Resource (1 per student)
Each group should get:
1 small (0.5 – 1 V) PV cell (search for “small PV cell” online, around $15)
Multimeter (again, search online, around $10)
2 wires with alligator clips
2 pieces are cardboard about the same size as the panel
Protractor (can be a physical protractor or print one online)
Ruler or one-foot length of string
Magnetic compass
Tape
Student worksheet
Sunlight (or a 100 watt incandescent lamp)
Watts Up in Solar Energy
Before the activity:
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Read through both the student and instructor resources so you have the
background information
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Make a collection of materials for each group.
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Test a solar panel and multimeter using the experimental setup described in
the Student Resource. Use the light source you’ll be using for the experiment.
You may need to adjust the ampere setting on the multimeter to get an
appropriate voltage reading.
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Save your experimental set-up so that you can use it as an example for
students.
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Find a space for the activity that will allow each group to set up their panels
and keep them in the same spot while working with the light source.
Watts Up in Solar Energy
Before the activity (continued):
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If students will be using paper protractors, print them and cut them out.
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Make enough copies of the Student Resource so each student has one.
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Make a copy of the Student Worksheet for each group.
Watts Up in Solar Energy
Solar engineers must consider not only the workings of the solar cell,
but how it’s installed.
The orientation of a solar panel has a significant effect on the cells’ efficiency. For
greatest efficiency, the solar panels must be oriented with their “faces” toward the
sun throughout the day.
Watts Up in Solar Energy
Two astronomical angles are most
important to consider. Imagine you’re
standing facing the sun:
Solar elevation is the angle formed by the
intersection of a line straight from you to the
sun, and a line straight from you to the
horizon. It’s a measure of the sun’s height
above the horizon.
Azimuth is the angle formed at the intersection
of that line toward the horizon and a second
line pointing due south. It’s a measure of the
sun’s north-south position in the sky.
Watts Up in Solar Energy
Activity procedure
(Note: If you’re working outside, you may want to divide the group into sets of 3-4 students,
distribute materials, and then move everyone outside before beginning the discussion of solar
cells and orientation.)
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Tell students you were thinking of having a friend install solar panels on your house. The
friend is very handy with a hammer, but doesn’t have a lot of engineering knowledge. But
installing solar panels seems simple enough, doesn’t it? You don’t really need to know
much, right? Ask students what factors they think would need to be considered. (By the end
of the activity, they should understand that it takes some specialized knowledge to properly
position solar panels.)
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If necessary, prompt students to recognize that the sun moves across the sky in a different
arc each day, and that the amount of light that the panel will absorb depends on how it’s
oriented relative to the sun’s movement. The more light it collects, the more efficient it is at
producing energy.
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Tell students that with this exercise, they’ll be making themselves far more qualified to install
solar panels than they are now!
Be sure each student has a copy of the Student Resource, and go over the information in it.
Be sure that students understand the concepts of tilt and orientation, and how they differ
(rotation around different axes and affected differently by motion of the sun).
Watts Up in Solar Energy
Activity procedure (cont’d)
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Be sure each student has a copy of the Student Resource, and go over the information in it.
Be sure that students understand the concepts of tilt and orientation, and how they differ
(rotation around different axes and affected differently by motion of the sun).
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Divide the students into groups of three or four and give each group a set of materials. If
you’re going to work with sunlight, move the whole class outside. If you’re working with
incandescent lamps, help each group find a spot to work in where they can do all their work
without having to move themselves or the lamp.
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Go through the instructions on the Student Worksheet, Show students your set-up and
demonstrate taking both tilt and orientation measurements. Help students as they put
together their solar setups, take their measurements, and plot their graphs. While they are
taking their azimuth measurements, remind them to recheck their tilt angle each time, to be
sure they take the measurement with the same tilt angle each time.
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When there are about 20 minutes left of the hour, give students a 5-minute warning that
they should answer the questions in the Student Worksheet.
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When there are 15 minutes left, gather the whole group together. Have each smaller group
share their answers to the first question, describing how they’d orient their panel based on
where they did their work. As a larger group, discuss the answers to the other questions.
Watts Up in Solar Energy
Assessment
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Each small group will explain to the others how they would install solar panels
in the place where they took their measurements, and will explain their choices
based on the data collected.
Watts Up in Solar Energy
Extensions
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Repeat the experiment at a different time of day or on another day when the
temperature is different. Record results in the same way and explain
differences in the results.
Construct a solar house with a light bulb or two. Try out each group’s
orientation suggestions and see if they can light up the bulb(s).
Watts Up in Solar Energy
Teaching tips
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If you know your students, take the reins on pairing students with each other. Be mindful
of students who seem to work together well, and those who distract each other. Try to
pair students that have complementary personalities.
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Circulate around the classroom as students are working and be sure to keep them on
track, answer questions, and encourage students who are less assertive.
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Give students a review of using graphs, if that seems necessary.
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Have your model on hand to use as a demonstration.
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In the final large group discussion, encourage quieter or less confident students to speak
up and share their thoughts.
Watts Up in Solar Energy
Takeaways:
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The orientation of solar panels has a significant effect on their efficiency:
Solar panels collect the most energy when they directly face the angle that sunlight is
coming from. It’s part of a solar engineer’s job to determine how to best orient solar
panels.
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A solar engineer has to take into account whether the panels will be able to move
with the sun. If they can’t (for example, if they’re on a rooftop), the engineer must
calculate which orientation will maximize direct exposure to the sun’s rays throughout the
course of the year.
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Solar elevation and azimuth are the two most important angles to consider:
These angles depend on where on the earth the solar panels will be, and what time of
year it is. Solar elevation azimuth change throughout the day and year.
Watts Up in Solar Energy
Resources and bibliography:
Watts Your Angle?
http://www.ext.colostate.edu/energy/k12-curr.html
A new angle on PV efficiency
https://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_pveff/
cub_pveff_lesson01_activity1.xml
Photovoltaic orientation and power output
http://www.fsec.ucf.edu/en/education/k-12/curricula/use/documents/
USE_16_PVOrientation.pdf
Solar angle calculator
http://solarelectricityhandbook.com/solar-angle-calculator.html
Watts Up in Solar Energy
Questions about the activity?
Contact Robin Marks
Discovery Street Science
discoverystreetscience@gmail.com