Lesson and Lab Activity with Photovoltaic Cells

Contributor
Cornell Center for Materials Research/Dan Delorme
Type Category
Assessment Materials Instructional Materials
Types
Informative Text , Experiment/Lab Activity
Note
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.

Reviews

Description

This resource provides background information about semiconductors and photovoltaic cells. Then it has three parts to the lab activity: (1) solar cell(s) and small electric fan, (2) Lifting small masses with an electric motor, and (3) Powering a light bulb. The first activity, solar cell(s) and small electric fan, simply requires the students to create an electric circuit of their design that incorporates at least one solar cell. The students are to measure the current and voltage of the array and compare them to the manufacturer values. The second activity, lifting small masses with an electric motor, again requires the students to design their own circuit containing at least one solar cell, but this time they also need to power an electric motor using the solar array. Their creation must lift a mass 0.5 m. They need to calculate the power of the solar array as it lifts the mass, determine the change in gravitation potential energy of the mass, and also calculate the efficiency of the motor. The third and final lab activity, powering a light bulb, requires the students to construct their own circuit with a solar array so they can power a light bulb and have it shine with various amounts of intensity. The students are to compare the power of the solar cell and the light bulb.

Intended Audience

Learner
Educational Level
  • Grade 12
Language
English
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

HS-PS3-3 Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.

Clarification Statement: Emphasis is on both qualitative and quantitative evaluations of devices. Examples of devices could include Rube Goldberg devices, wind turbines, solar cells, solar ovens, and generators. Examples of constraints could include use of renewable energy forms and efficiency.

Assessment Boundary: Assessment for quantitative evaluations is limited to total output for a given input. Assessment is limited to devices constructed with materials provided to students.

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
To fully address and meet the PE, this activity needs to require the students to refine or modify their circuits so as to improve efficiency and/or power output.

Science and Engineering Practices

This resource appears to be designed to build towards this science and engineering practice, though the resource developer has not explicitly stated so.

Comments about Including the Science and Engineering Practice
While the students have not developed the model of gravitational potential energy, they can use it to calculate the change in gravitational potential energy that results from the electric motor lifting a mass. The instructor will have to teach this concept at this point if it hasn't already been covered in the course. Furthermore, the instructor may need to discuss models with their class.

Disciplinary Core Ideas

This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.

Comments about Including the Disciplinary Core Idea
This activity clearly shows solar energy being converted into electrical energy as the solar array powers a fan, a motor, and a light bulb. Furthermore, the activity also clearly demonstrates electrical energy being converted into mechanical energy as the motor is used to lift a mass. This mechanical energy results in a change in the Gravitational Potential Energy. Underlying the DCI is the implicit understanding that solar radiation travels from the sun to earth. These ideas could be extended to help the students understand the Law of Conservation of Energy. To fully address the DCI, the teacher should provide instruction on how light is created in a star, how it travels through space to the earth, how it is converted into electrical energy via the photoelectric effect, and how electrical energy powers a motor to lift a mass. Instruction about the Conservation of Energy should be provided to tie all of these concepts together and directly relate them to the DCI.

Crosscutting Concepts

This resource appears to be designed to build towards this crosscutting concept, though the resource developer has not explicitly stated so.

Comments about Including the Crosscutting Concept
The second activity, lifting a small mass with a motor, requires the students to determine the efficiency of the motor. Their results could be used as the basis for a discussion about the Conservation of Energy. The change in Gravitational Potential Energy will not equal the energy produced by the solar array, so the instructor may need to help guide the students to explain why it doesn’t. The students may need help understanding how energy is conserved in the face of these energies not being equal. The use of solar cells in this activity could lead to a class discussion on how semiconductors are used for various applications in real life.

Resource Quality

  • Alignment to the Dimensions of the NGSS: Elements of the DCIs are significantly addressed. The activity slightly connects to engineering because students used modern technology, solar cells, to power devices and perform tasks. The engineering connection could be made stronger if the activity required students to modify and refine their lifting devices. The connection to science is strong, but could be strengthened if the activity required students to explain at each step why the efficiencies are less than one. The Law of the Conservation of Energy is contained in this activity, but the activity should require the students to use it and explain how it applies to the measurements they make. Finally, the Cross Cutting Concepts are suggested. The instructor may need to lead a whole class discussion on the Law of Conservation of Energy after completing this activity to help students understand why the efficiencies are less than one because the activity alone doesn’t significantly address that.

  • Instructional Supports: The activity provides plenty of background information about semiconductors and solar cells. However, it is assumed that the students are already comfortable with electrical circuits and how to perform calculations using data obtained from circuits as none of that information is provided.

  • Monitoring Student Progress: Because students need to collect, record, and manipulate data, the activity does provide a method for monitoring student progress. A teacher could use the results of this activity as the basis for a whole class discussion about the Law of Conservation of Energy. The extension/internet activities at the end of the lab do not address the standards and could easily be ignored or replaced with questions that focus on the NGSS. For example, to help the students apply what they learned from the lab to the real world, and to address engineering issues, a teacher could ask the students to use the efficiency rating of the solar cell they measured to determine how many square feet of that solar array they would need to power a car, or other practical, everyday device.

  • Quality of Technological Interactivity: - none -