Solar Photovoltaic Open Inquiry Experimental Design Project
Goal: The goal for this learning sequence was to learn via experimentation how a measurable factor (variable) influences the performance of a solar cell, module, or simple photovoltaic system. Students will come to appreciate why solar PV systems yield highly variable power output over time. Students will also learn to work cooperatively and in collaboration with peers of diverse abilities and background knowledge.
Objectives: The objectives (benchmarks toward achieving the goal) for this learning sequence were:
1) Demonstrate competency in the design and implementation of a controlled experiment in an open inquiry setting.
2) Use evidence to explain in a written report how the manipulation of one variable affects the current, voltage, and/or power output of a simple photovoltaic system under controlled conditions.
3) Use oral presentations to compile the results of several (4) group experiments.
4) Demonstrate knowledge of how each variable influences PV performance in a summative assessment (Unit Test).
Written reports of research findings were graded on a pass/fail basis. The is out of the ordinary as I usually require individual reports even on group projects, which a graded as a summative assessment on a sliding scale (A-F grades). The rationale for going pass/fail was to reduce the apprehension students might have about being graded on group work. I didn’t want the “over-achievers” to take heavy handed control of the entire process just so they could ensure a quality grade. Likewise I didn’t want the lower functioning kids to lose confidence in their ability to contribute. Cooperation was one of my objectives.
A unit test consisting of multiple choice and open response questions (format similar to MCAS).
Student Prior Knowledge:
Before initiating this open inquiry project, students learned (through research, demonstrations, video discussion, and direct instruction) about the following topics:
• Energy and Power
• Electromagnetic radiation (light).
• Simple circuits, Ohm’s law (voltage = current x resistance),
• Power = voltage x current
• Solar Cell open circuit voltage; solar cell short circuit current
• Sun/earth relationships resulting in seasonal variations in the duration and intensity of solar insolation (light intensity in Watts/m2).
• Environmental conditions affecting solar insolation (clouds, aerosols, temperature, altitude, zenith angle etc…)
• General design of a controlled experiment
• Definitions of experimental, dependent, and control variables.
Materials provided by the teacher:
• A variety of small solar modules (pictured below)
• Artificial light source (incandescent lamps, 150 Watts)
• Ring stands with clamps
• Wires and alligator clips
• Multi meters
Brief project summary:
This project is part of an elective course called “Sustainable Energy.” Students are grades 11 and 12. In terms of abilities and motivation, this is a diverse bunch. I have students who have demonstrated success in multiple AP level courses working side by side with individuals who have had to repeat core academic classes.
To initiate this project, students were asked during a warm up (“Do Now”) to brainstorm as many variables as they could think of which might affect solar module current, voltage, and/or power. This phase of the project served as a formative assessment and review of topics covered during the previous units (see prior knowledge above). The brainstormed list was compiled and discussed. Students were then allowed to choose their own groups of 3-5 individuals. Class time and access to computers was given to develop their ideas. Each research team (there were 4 in total) was required to submit a project proposal before they could begin their experiment. The proposal requirements included a project title, problem statement, hypothesis, identification of the experimental variable, dependent variable(s), and at least three control variables, as well as a thorough step-be-step procedure. Class time was also provided to perform the experiments, make revisions to procedural details, and write up the results and discussion.
This open inquiry experimental design project is just one piece of a larger unit covering solar photovoltaics. In addition to the student work samples, I will also upload a curriculum map to give you a broad sense of the topics covered. The entire unit is being implemented in two parts, a fall sequence and a spring sequence. The fall sequence will be concluding this Friday, with a traditional unit test similar in format to an MCAS.
I will be sharing two of the completed written reports with you. Although students have received feedback from me, I am sharing their first draft submissions prior to any revisions that I may have suggested. As such, the quality of the work is wholly their own doing, and each report contains some errors. Each report was the result of collaboration among group members. You may notice that some paragraphs or report sections are more/less grammatically correct than others, a reflection of the writing abilities of diverse members.