The Arizona STEM Acceleration Project

Solar Array

Solar Array

A 9-12th grade STEM lesson

Victoria Imhoff

Date: June 1st, 2024

Notes for teachers

• This lesson takes place in a laboratory classroom over one class period.
• Students may work in small groups of 2-4.
• Identify a group leader to maintain lab space and supplies.
• Facilitate student reflection on analysis and conclusion questions as the assessment.

List of Materials (Per Group)

Per pair of students:

• Device with calculator
• Device with timer
• Digital multimeter (DMM)
• Electric motor
• Lamp with an incandescent bulb with power source
• Masking tape
• Photovoltaic cell
• Paper, copier
• Ruler, English
• Wires with alligator clips, black
• Wires with alligator clips, red

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Per student:

• Notebook
• Pencil

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Math Standards

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AgriScience Standards

Objectives:

Construct a solar energy system and compare the production of electricity under different light conditions.

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Agenda (55 minute, 1 Class Period)

Bellwork Question (2-4 minutes): Where is solar energy most productive?

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Answer: The highest solar energy potential on Earth happens to be near the equator, surrounded by an arid climate away from major sources of pollution

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Complete Table I Predictions (5 minutes)

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Part 1: The Power of Solar (15 minutes)

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Part 2: The Power of Solar (15 minutes)

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Complete Table II & Answer Part II Analysis Questions (5-7 minutes)

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Part 3: Calculating Watts & Part III Analysis Questions (5-8 minutes)

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Conclusion Questions/Debrief (7 minutes)

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Popcorn Read

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When people hear solar energy, they think of the desert where the sun's intensity is most significant. However, solar energy is present on the rooftops of homes and businesses in the United States. Solar power is inexpensive to produce after the initial cost of materials, and there is no pollution from solar energy production. The tradeoffs of solar energy include the lack of energy production on cloudy days and nighttime and the high cost of building materials. Farms and larger properties with large structures, such as barns, have the necessary area to add solar panels and supplement their electricity use.

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Solar panels produce electricity when light reacts with electrons in

a photovoltaic cell. The amount of energy produced by photovoltaic

cells depends on the light intensity, light quality, and the angle of

the photovoltaic cell in relation to the light source. The season and

time of day influence light intensity. The more direct the light, the

greater the light intensity. For instance, noon on a bright summer

day. Light quality is related to how much light reaches the

photovoltaic cell. The amount of electricity produced by solar

energy is affected by the amount of sunlight available. Cloudy days

and dirty cells will produce less energy than clean cells and non-

cloudy days.

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Calculating Power

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Electrical power (P) in a circuit is a product of the voltage (V) and the current (I). Watts Law is the calculated relationship between power, voltage, and current.

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power (P) = current (I) x voltage (V)

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How much light does it take to produce solar power? Can you still produce energy on a rainy day?

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Table 1 Setup

Goal: Duplicate this table into your student notebooks or a designated blank sheet of paper. This table will be used for predictions.

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Table 2 Setup

Goal: Duplicate this table into your student notebooks or a designated blank sheet of paper. This table will be used for predictions.

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Part 1: The Power of Solar

Goal: With your partner, simulate the energy produced by photovoltaic cells. Then, determine the cost of powering electronics using solar energy.

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1. Predict how light intensity and quality affect the power produced by the photovoltaic cell. Record your prediction on Table 1 in your student notebook or piece of paper.
2. Turn the digital multimeter (DMM) to the continuity setting (looks like a wifi symbol).
3. Touch the black and red leads of the DMM together to
4. test continuity. The multimeter should read OL when separate and 0.0 when they are touching.
1. If you get different ratings, the lead connections within the multimeter may be loose or broken.
5. Attach the DMM to the photovoltaic cell. Refer to image above.
6. Attach the red lead to the positive side of the
7. photovoltaic cell.
8. Attach the black lead to the negative side of the photovoltaic cell.

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Part 1: The Power of Solar (Cont)

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1. Install the light bulb, then plug in and turn on the incandescent lamp.
2. Position the light bulb four inches from the solar cell to simulate direct sunlight.
3. Prepare the DMM to measure the source voltage of the photovoltaic cell with a light 4 inches away.
4. Turn the DMM dial to V 20. The "20" signifies that the DMM cannot read over 20 volts in this
5. setting.
1. Plug the black probe into the COM port.
2. Plug the red probe into the port that includes V.
6. Record the Voltage in Table 2 on your student notebook.
7. Prepare the DMM to find the current of the variable.
8. Turn the DMM dial to A 20m. The 20m signifies that the largest reading the DMM can make at this setting is 20 milliamps (mA) or 0.02 amps.
• Leave the black probe into the COM port.
• Plug the red probe into the port that includes mA.
9. Record the Current (mA) in Table 2 on your student notebook or piece of paper.
10. Position the light bulb 12 inches from the solar cell to simulate indirect lighting.

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Part 1: The Power of Solar (Cont)

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1. With the light positioned 12 inches from the solar cell, place a white sheet of paper between the light and the photovoltaic cell to simulate a cloudy day.
1. Repeat Steps 8–9 from previous slide.

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2. Turn off the light and place the solar cell face down on the desk to simulate darkness.

• Repeat Steps 8–9 from previous slide.

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3. Turn off the DMM and disconnect the wires.

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Part 2: The Power of Solar

Goal: With your partner, simulate the energy produced by photovoltaic cells. Then, determine the cost of powering electronics using solar energy.

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1. Make a flag on the axle of the electric motor using a piece of masking tape.
1. See image for an example.
2. Connect the photovoltaic cell and electric motor together using image as an example.
3. Attach one end of a red wire to the positive side of the photovoltaic cell and the other end to the positive side of the electric motor.
4. Attach one end of a black wire to the negative side of the photovoltaic cell and the other end to the negative side of the electric motor.
5. Turn on the incandescent lamp.
6. Position the light bulb four inches from the solar cell to simulate direct sunlight.
7. Count the number of times the flag on the axle makes a
8. complete rotation, 360 degrees, for 15 seconds.
9. Record the number of Motor Rotations in Table 2.

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Part 2: The Power of Solar

Goal: With your partner, simulate the energy produced by photovoltaic cells. Then, determine the cost of powering electronics using solar energy.

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1. Position the light bulb 12 inches from the solar cell to simulate indirect lighting.
1. Repeat steps 7-9 of previous slide.
2. With the light positioned 12 inches from the solar cell, place a white sheet of paper between the light and the photovoltaic cell to simulate a cloudy day.
• Repeat steps 7-9 of previous slide.
3. Turn off the light and place the solar cell face down on the desk to simulate darkness.
• Repeat steps 7-9 of previous slide.
4. Answer Part Two Analysis Questions.

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Part 2: Analysis Questions

Goal: Work with your partner to complete the analysis questions under table 2 in your student notebook or a designated sheet of blank paper.

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Part Two Analysis Questions

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1. How did your results compare to your predictions?

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2. What is the relationship between light intensity and voltage?

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3. How does light intensity affect the power of the motor?

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Part 2: Analysis Questions

Goal: Work with your partner to complete the analysis questions under table 2 in your student notebook or a designated sheet of blank paper.

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Part Two Analysis Questions

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1. How did your results compare to your predictions?

Answer: Varies

2. What is the relationship between light intensity and voltage?

Answer: There is an increase in light intensity when voltage increases

3. How does light intensity affect the power of the motor?

Answer: The more intensity, the more power of the motor

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Part 3: Calculating Watts

Goal: With your partner, simulate the energy produced by photovoltaic cells. Then, determine the cost of powering electronics using solar energy.

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1. Calculate the power of the light held 4 inches away by multiplying the Current by the Voltage. Record the Power (mW) in Table 2.

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2. Remember: power (P) = current (I) x voltage (V)

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3. Repeat Step 1 for each variable in Table 2.

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4. Answer Part Three Analysis Questions.

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Part 3: Analysis Questions

Goal: Work with your partner to complete the analysis questions under table 2 in your student notebook or a designated sheet of blank paper.

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Part Three Analysis Questions

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1. What is the relationship between light intensity and power?

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2. What is the relationship between power and motor rotations?

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Part 3: Analysis Questions

Goal: Work with your partner to complete the analysis questions under table 2 in your student notebook or a designated sheet of blank paper.

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Part Three Analysis Questions

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1. What is the relationship between light intensity and power?

Answer: Solar cells depend on light intensity to deliver power. The higher the light intensity the more power generated by the solar cell.

2. What is the relationship between power and motor rotations?

Answer: The motor rotated more times when there was more

power and fewer times with lower power.

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Assessment/ Conclusion Questions

Goal: Work individually to complete the conclusion questions in your student notebook or a designated sheet of blank paper.

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Conclusion Questions

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1. Why does solar energy classify as an alternative energy source?

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2. How can solar energy benefit agriculturalists?

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Once completed, please clean up and return materials to teacher.

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Conclusion Questions

Goal: Work individually to complete the conclusion questions in your student notebook or a designated sheet of blank paper.

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Conclusion Questions

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1. Why does solar energy classify as an alternative energy source?

Answer: Solar energy, which is harnessed from the sun's light, is a renewable energy source because it isn't depleted when used.

2. How can solar energy benefit agriculturalists?

Answer:Potential benefits for farmers include diversifying revenue and increasing farm profitability; on-farm energy production; reducing irrigation water needs by shading the plants; improving crop yield, especially in dry or hot areas; and improving crop resistance to extreme weather, such as droughts.

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Differentiation

To remediate this lesson on solar energy create a comparative analysis chart. Students would list different types of solar technologies (like photovoltaic vs. concentrated solar power), detailing their efficiencies, costs, and environmental impacts. Another approach could be a hands-on experiment where students build simple solar collectors using readily available materials, assessing factors like heat absorption. This activity reinforces key concepts through practical application and critical thinking, addressing varying learning styles while ensuring comprehension and engagement in understanding solar energy applications and implications

Remediation

Extension/Enrichment

An extension activity for students can involve a hands-on project where students create simple solar ovens. Using materials like cardboard boxes, aluminum foil, plastic wrap, and black construction paper, students construct their ovens and test their effectiveness by cooking small items like s'mores. This activity reinforces concepts of solar energy absorption, reflection, and thermal insulation. Students can compare the temperature changes inside their ovens and discuss the efficiency of different designs, deepening their understanding of how solar energy can be harnessed and utilized in practical applications.