## Objectives

Students will develop a solar panel system that adjusts the angle of the solar panel in relation to the sun to obtain optimal output. Using an inquiry-based approach, students will investigate and find the optimal angle between the light source and solar panel.

## Planning

To get started with this project, the teacher should have the following tools ready prior to class:

• A Fable joint module
• Solar panels
• Voltmeter
• Ammeter
• Light bulb or a resistor
• Optional: LEGO bricks to build a holder for the solar panel
• Powerful halogen light bulb (500 w) in case there is no sunlight
• Assignment sheet

Duration: 6 lessons (6 x 45 minutes)

## Images for assignment

The-suns-angle-in-zenith-over-Copenhagen-summer-and-winter.png

## Learning activities

Prior to the project, the class should work with alternative energy sources so that students are familiar with the various technologies that exist. It is also important that students know how to use an ammeter and voltmeter, and that they can construct simple electrical circuits.

The class is divided into groups of 2-4 students.

Before the groups start programming and developing their system, they must research the conditions for optimum output of a solar panel. The efficiency of a solar panel is greatest when the sun’s rays hit the panel from a perpendicular angle. Students must relate this fact to the sun’s location in the sky and the orientation of the solar panel. The system must also be able to distinguish between summer and winter, given that the height of the sun in the sky varies throughout the year.

To examine the output of their system, students measure the current and voltage of their setup. It is important that a light bulb or suitable resistor is included in the circuit so that students can measure the current in the solar panel system. The size of the bulb depends on the power produced by the solar panels and the number of solar panels used in the experiment. This must therefore be investigated before the material is taken into use.

Fable is then programmed to ensure that the solar panel gets maximum sunlight. Students must here be able to describe the optimal path for the solar panel to follow. Here, it is also possible to differentiate the task. The system can be simplified by only considering the time of day at which the sun is at its highest point (zenith). The group then builds an electronic control system that takes into account the sun’s position in the sky in winter and summer. The project illustration shows the sun’s position (at zenith) over Copenhagen in summer and winter.

To increase the project’s difficulty, the functionality of the system can be expanded so that the system is able to adjust the angle of the solar panel at morning, midday, and evening in summer and winter respectively.

Students can also choose a different location in the world to develop the system for. The online almanac found at http://www.suninfo.dk/solhojde/solhojde.php can be used to find the sun’s height throughout the year. Note that students should make sure to stay within the northern hemisphere, because otherwise all directions will need to be reversed.

Finally, the students prepare a presentation of their system. It is therefore important that groups document their work throughout.

## Evaluation

Class evaluation where students present their results.

In addition, students complete a self-evaluation form. This evaluation is intended for the students’ own use but can also be used by the teacher in connection with future lessons.

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