Hello Solar World: A Micro Power Plant

Teacher Guide: A Lesson Plan For Middle School Students

Subject: Science & Electronics

Grade Level: Middle School (Ages 11+)

Topic: Introduction to Solar Energy

Time Allotment: 50 minutes

Learning Objectives:

Define what solar energy is
Explain how solar panels work
Identify the benefits of solar energy
Identify characteristics of solar energy
Activity 1: Build a simple circuit to power a flashing LED off light (Group Project)
Activity 2 (Optional): Design a energy harvesting solar device (Group Project)

Supplies

General Materials:

Whiteboard + Markers
(Optional) Projector or TV for Intro Video

Student Materials Kits: Outdoor Solar Energy Plant

(Multiply items by number of student groups)

Solar panel, 3+ volt, (0.04 A / 40mA+), up to 5 volt solar panel can be used
Flashing Red LED
Window or bright light source

Challenge Project Materials: Indoor Solar Energy Plant

(Multiply items by number of student groups)

Capacitor 2000uF +
2N3904 NPN transistor
2N3906 PNP transistor
2.2 kOhm Resistor ¼ watt
Solar Motor or Buzzer 1.5v+
Solderless breadboard
Jumper wires

Step 1: Introduction

Estimated Time 15 minutes

Ask the students what they know about solar energy and write their idea on the board. Some idea prompts can be:
Where does solar energy come from
(Sun or artificial lighting or other sources that emit light like lightning bugs or fire)
How long does it take to get from the Sun to Earth?
(8 minutes 20 seconds)
What are names for the devices that convert sunlight into electricity?
Solar Panel
Solar Cell
Solar Battery (original name)
Photovoltaic (Scientific name)
What can solar energy power do?
Power anything that is electric, storage is often needed
Solar Impulse, an airplane powered only by solar energy flew around the world
Solar energy powers the International Space Station
Solar powers all of the GPS navigation satellites
What is the oldest solar cell?
One of the first mass production solar cells was the Weston Photronic. It was made in the 1930s to power light meters and relay switches. They were often used for fire detection. They are still used today.

Explain how solar energy uses light from the sun to generate electricity. Show a picture of the sun or draw a picture and show how it produces light and heat we feel.
Talk about the spectrum of light. UV, Visible, and Infared
Solar energy can be harnessed from artificial sources as well. A photon is a photon.

(Optional) Play a short video that talks about solar energy from National Renewable Energy Lab (NREL)
NREL Energy Basics: Solar

Step 2: Activity 1: Hello World to Solar Energy: Your First Power Plant

Estimated Time 15 Minutes:

Background:

This activity will give students the opportunity to power an LED using solar energy using a simple circuit. One of the key advantages of solar energy is that it can be scaled from very small power generation like the ¼ watt of power it’s producing in your hand to gigawatts of power that can run cities.

Fun Fact: You may have noticed the symbol for a solar cell and LED look very similar. But one of them has arrows pointed toward it and the other one points away. The arrows represent photons of light. So, one accepts photons and the other is an emitter. An LED and a solar cell are both very similar electrical devices. LEDs can generate electricity if exposed to sunlight and if you run a power backward through a solar cell. It will emit infrared light. This property of solar cells is used for performing quality tests on solar panels.

Step 3: Activity 1 Steps:

Divide students into pairs or small groups. A recommended maximum of 4 students is suggested per kit.
Provide students with the materials to build their first solar power plant. (Multiply items by number of student groups)
3v+ Solar panel with lead wires
Flashing Red LED or low voltage motor
Sunlight window or bright light source
Explain how to assemble the circuit. There is only one correct way to hook it up together.
Explain how a solar panel works
Let the students try out their mini power plant in a light source, the LED will flash under most light sources.
Have the students experiment with moving the solar panel closer and further away from the light. How does that affect the brightness of the LED?

Step 4: Post Activity

Ask the students what was the most surprising thing they learned. Have them talk about what other things they think in their world that could be powered by solar power?

Step 5: Activity 2: Indoor Solar Energy

Estimated Time 15 Minutes:

Overview: The previous experiment showed how we can directly use solar energy to power a device. In this experiment, we are able to capture and store the solar energy for use at a later time. This can be used in bright light or very dim light as well. Since light is a form of energy, if you can see, there is energy that can be harvested.

A lot of products are able to use solar energy from indoors. One of the most successful products to use indoor solar energy is the calculator. Solar calculators were first released in the mid-1970s and became a primary way to power the devices. Different types of solar cells were developed that allowed for better harvesting of indoor solar energy to make the products even cheaper and more accessible.

Step 6: Activity 2: Steps

Steps:

Divide students into pairs or small groups. A recommended maximum of 4 students is suggested per kit.
Provide students with the materials to build an energy harvesting mini solar plant. (Multiply items by number of student groups)
Capacitor 2000uF +
2N3904 NPN transistor
2N3906 PNP transistor
2.2 kOhm Resistor ¼ watt
Solar Motor or Buzzer 1.5v+
Solderless breadboard
Jumper wires
Explain how to assemble the circuit. There is only one correct way to hook it up together.
Let the students try out their mini indoor power plant. The circuit will collect solar energy and store it in a capacitor and let it our the energy in a burst. The more light that it receives the faster it will recharge.
Have the students experiment with moving the solar panel closer and further away from the light source. How does that affect the recharge time of the capacitor?
Discussion, talk about what is happening. How is the solar energy being stored? What type of applications can be utilized using power sources like this? What would the effect be using a larger capacitor?

Step 7: Post Discussion:

Ask the students again, what was the most surprising thing they learned. Have them talk about what other things they think in their world that could be powered by solar power. See what new opportunities adding storage may open up?