Introduction

In this multi-day, student-driven investigation, students act as solar energy consultants tasked with answering the question: Can a solar array effectively charge our school’s laptops? Students conduct background research and design their own controlled experiment to investigate a specific factor that affects photovoltaic (PV) performance as part of this broader challenge.

After proposing and refining their experimental design, student teams carry out their investigation, collect and analyze data, and draw evidence-based conclusions about PV efficiency. The investigation culminates in a scientific presentation, where students communicate their methods, results, and conclusions, and apply their findings to evaluate a solar solution for their school.

Student Objectives

Students will be able to:

• Define Energy Needs and Design Constraints
  • Quantify the energy required to charge a specified number of school laptops.
  • Identify key parameters influencing energy demand (e.g., device wattage, charging time, number of devices, usage patterns).
• Model and Size a Solar Array Solution
  • Calculate the solar array size needed to meet the energy demand, including adjustments for efficiency losses and variable sunlight. 
  • Apply energy and power relationships to predict system output under different conditions.
• Select and Justify an Optimal Site
  • Analyze and compare two potential school sites using criteria such as sunlight exposure, environmental impact, accessibility, safety, and available area.
  • Use quantitative and qualitative evidence to justify the selection of an optimal site. 
• Investigate Solar Photovoltaic Efficiency
  • Develop a testable question and design a controlled experiment with clear procedures.
  • Identify independent, dependent, and controlled variables affecting PV performance.
  • Plan how data will be collected and recorded using appropriate tools (e.g., voltage, current, power).
  • Conduct the experiment and collect accurate data.

• Analyze and Interpret Data
  • Organize and visualize data using graphs, tables, or other representations.
  • Calculate power, efficiency, and percent changes across conditions.
  • Interpret how variable changes affect PV performance and relate findings to real-world systems.
• Communicate and Defend Engineering Decisions
  • Synthesize experimental results into evidence-based recommendations for solar array design and siting.
  • Develop and deliver a scientific presentation integrating data, visuals, and reasoning.
  • Clearly communicate and defend conclusions to a peer or stakeholder audience.

Project Timeline Overview

The project timeline is flexible and could be conducted over several weeks.

Materials

1. Instructional Resource
   • Guiding Slides (Parts 1-3)

2. Student Handouts
   • Student Handout Project Timeline and Tasks
   • Student Handout: Part 1
   • Student Handout: Part 2
   • Student Handout: Part 3
   • Student Handout: Part 4
   • Student Handout: Part 5
   • Science notebook or digital document (for recording work and responses)

3. Background Research Resources
   • Introduction to Solar Video 
   • Science of Solar Video 
   • Science of Solar – Extended Reading 

4. Student-Designed PV Efficiency Lab Materials (Parts 3-4)
   • Basic Materials (required for every group)
   • Mini PV cell (Example: Amazon Mini Solar Panels)
     Note: If available, larger panels will produce higher voltage and current, resulting in more consistent and easier-to-measure data. 
   • Multimeter
   • Electric tape
   • Protractor
   • Ruler or tape measure
   • Light source (Incandescent bulb or lamp)
     Note: Incandescent bulbs are preferred, as heat lamps can become extremely hot and pose a safety risk. 
   • Graph paper or digital graphing tool
   • Wire stripper, if needed
   • Power strip or extension cord if needed

5. Additional/Design-Dependent Materials: Materials will vary depending on the independent variable chosen for each team’s experiment.
   • Shading or Light Intensity
     • Colored filters; transparency film; mesh screens; paper; fabric
     • Light meter or smartphone light meter app
   • Tilt Angle
     • Protractor
     • Cardboard to make wedges or stands
   • Temperature
     • Heat lamp (for warming: extreme caution and safe distance necessary to avoid overheating the PV unit)
     • IR thermometer
     • Ice or cooling packs; fans
   • Color or Filter
     • Colored cellophane; plastic filters; transparent paints
   • Advanced
     • Pyranometer (for accurate light irradiance measurement)
     • Small DC motor (rated for ~1.5–3V, low current; for realistic current draw simulation)

Procedure

Day 1: Background and Demand Estimation

1. Launch the investigation using the Guiding Slides, introducing the driving question.
2. Organize students into teams of 3-4.
3. Provide each team with the Solar Investigation Timeline and Tasks handout.
4. Review the investigation sequence and expectations, and address questions.
5. Provide each team with the Student Handout Part 1.
6. Continue to use the Guiding Slides to lead students through the questions that help them calculate energy use for charging a single laptop computer. 
7. Discuss how to determine the total number of laptops and the average charging time per device. 
8. Review student responses individually or as a class, and have teams submit their total daily energy demand and estimated number of panels with justification.

Day 2: Site Selection and Evaluation

1. Provide each team with the Student Handout Part 2.
2. Teams are tasked to identify and evaluate two potential PV installation sites.
3. Introduce evaluation criteria: sunlight exposure, environmental impact, accessibility/safety, and available area.
4. Teacher Choice: Choose one analysis method.
   1. Desktop analysis with Google Earth. Teams capture screenshots and annotate to provide reasoning.
   2. Site walk around the school property. Student teams evaluate site conditions with video/photo evidence.
5. Emphasize evidence-based reasoning for all claims.
6. Student teams select the optimal location and justify their choice.

Day 3: Designing the PV Efficiency Lab

1. Provide each team with the Student Handout Part 3.
2. Provide students with the Science of Solar: Extended Reading to build background knowledge and to use as a resource as they work on their lab proposal.
3. Using the Guiding Slides, conduct a teacher demonstration on PV and multimeter basics.
   1. Measuring PV Output (slide 14, text only)
      1. Explain that panel output can be described using:
         1. Voltage (V) and Current (A), both of which change depending on conditions.
         2. Power (W), calculated using:
            Power (W) = Voltage (V) x Current (A). 
      2. Explain that students may choose to:
         1. Record voltage only (simpler setup, demonstrated below).
         2. Measure both voltage and current, and calculate power during data analysis (advanced only; requires a closed circuit with a small DC motor rated 1.5-3V, low current; demonstrated below)
   2. Introduce the Equipment (slide 15, images included)
      1. PV cell
      2. Multimeter
         1. Probes: red (+) and black (-)
         2. Ports: COM (black) and VΩmA or similar (red)
         3. Dial settings: DC V(voltage); DC A(current)
   3. PV setup (slide 16, text only)
      1. Angle and Distance: Keep the lamp at least 1 ft above the PV cell as a consistent baseline. If using a heat lamp (not recommended), more distance is needed (2ft) as they get extremely hot and may melt the PV unit if too close.
      2. Use a ruler or tape measure to show how changing distance affects light intensity.
      3. Use a protractor and wedges to demonstrate measuring panel tilt.
   4. Safety Protocol If Using a Heat Lamp (slide 16, text only)
      1. Remind students that heat lamps become extremely hot during use and require caution.
      2. Ensure the lamp is securely positioned before turning it on. It should not be adjusted while in use.
      3. Keep the lamp at least 2 feet away from the PV panel to prevent damage or melting.
      4. Turn off the lamp when not in use.
      5. Do not allow students to touch the lamp or PV panel after use—both may remain hot.
      6. Allow the lamp and panel to cool between trials when testing temperature effects.
   5. Measuring Voltage: Open Circuit: Basic (slide 17, image included)
      1. Set the multimeter to DC voltage.
      2. With electrical tape, connect the red lead to the PV cell’s positive terminal, and the black lead to the negative terminal.
      3. Place the cell under a lamp or in sunlight.
      4. Show how voltage changes with light intensity or angle.
      5. Note that this is the open-circuit voltage (electrical potential difference). 
   6. Measuring Voltage and Current: Closed Circuit: Advanced (slide 18, images included)
      1. Measure Current: Set the multimeter dial to DC current (A).
      2. Build a complete circuit using your solar panel (PV), a small load (like a small DC motor, rated at 1.5-3V) and electrical tape.
      3. Break the circuit at one point—this is where the meter goes.
      4. Insert the multimeter in series so current must flow through it.
         1. Connect one PV lead to the multimeter.
         2. Connect the other multimeter lead to the load.
         3. Connect the other side of the load back to the PV.
      5. Shine light on the panel and observe the current reading.
      6. Measure Voltage: Remove the multimeter from the circuit.
      7. Reconnect the circuit so it is complete again. Expose the connections (using sticky electrical tape) so that the multimeter probes can touch them.
      8. Set the multimeter to DC voltage (V). 
      9. Touch one probe to each metal connection point on the motor. 
      10. Observe the voltage reading.
      11. Change the angle or distance of the light, repeat, and watch how the current and voltage change.
   7. Demonstrate Measuring Power Under Load: Advanced (slide 19, text only)
      • Use the formula Power (P) = Voltage (V) x Current (A)
      • Record voltage and current under identical light conditions and multiply to find power. 
      • If voltage is recorded in millivolts (mV) or current in milliamps (mA), convert both values to volts (V) and amperes (A) before calculating power. 
4. Guide student teams through writing their lab proposals. Students will define a testable question, identify independent, dependent, and controlled variables, and draft procedures for three variable levels and at least three trials per level. 
5. Sign off on approved proposals. Optionally, conduct a feedback session.
6. Ensure students track their materials and have what they need for the next session. 

Day 4-5: Conducting the Experiment

1. Provide each team with the Student Handout Part 4.
2. Confirm all teams are using approved procedures, and review safety and consistency expectations.
3. Students conduct experiments, collecting voltage and current data. 
4. Encourage documentation (photos/videos) to use in scientific presentations.
5. Each group should complete a data table and initial graph of results, and complete reflection questions in the student handout.
6. Student teams may need assistance calculating averages and percent changes across variable conditions.

Days 6-7: Data Analysis and Presentation Prep

1. Provide students with the Student Handout Part 5.
2. Provide work time for teams to analyze data and finalize graphs, synthesize results into conclusions, and develop their presentation materials (poster or slides).
3. Ensure all students are prepared to present.

Day 8: Scientific Presentations

1. Student teams deliver 5-7 minute presentations.
2. The audience participates through active listening and Q&A. 
3. Optional: Invite additional evaluators, such as teachers, students, and administrators.
4. Use the rubric to assess presentations.

Scientific Presentation Assessment Rubric