Building A Solar House

Buildings that are called “green” or “environmentally sustainable” are designed to use energy as efficiently as possible. The designers’ goals are to improve the quality of human life and to minimize detrimental effects on the environment, such as depletion of natural resources. In Missouri, Washington University’s Tyson Living Learning Center achieves sustainability by incorporating green technologies in different ways, including the use of solar panels.

In this activity, students will explore how solar panels work by building a simple circuit, a series circuit and a parallel circuit, using a solar panel to light a bulb and comparing which method yields the brightest light. Then students will build a solar-powered house using a shoebox, and test some variables to determine the most efficient way to harness solar energy to power a model home.

Grade Level: 6th – 8th grade
Subject Matter: Physical Science
National Standards: NS.5-8.1, NS.5-8.2, NS.5-8.5

Creating A Living Building

Architects have been leaders in designing green buildings. For example, Washington University's Tyson Living Learning Center in Eureka, MO, achieves the Living Building Challenge — a set of green guidelines that measure a building based on its performance. The building's architect Dan Hellmuth, of Hellmuth & Bicknese Architects in St. Louis, and Kevin Smith, associate director of Tyson Research Center, point out some of the Center's greenest features.

Activity Materials
(All materials listed are for each student or each group of students)
Shoebox with lid
Electrical tape
Scissors

The following materials can be purchased for each student or group of students from www.shop.pitsco.com or www.kelvin.com:
Four insulated wires with alligator clips
Two 6-volt mini-bulbs with socket base
Mini-solar panels with alligator clips

Vocabulary
Sustainable: capable of being continued with minimal long-term effects on the environment.
Photovoltaic: a material that converts light energy into direct-current electricity.
Resistor: an electrical device, such as a light bulb, that resists the flow of an electrical current.
Simple circuit: a pathway for electricity to flow in one continuous path. A simple circuit consists of one electrical source, one conductor and one resistor.
Series circuit: a pathway for electricity to flow in one continuous path that consists of multiple resistors connected in a series.
Parallel circuit: a pathway for electricity that consists of multiple pathways and resistors.

What To Do

Notes: Students should have a basic understanding of electricity and electrical circuits. Students or teachers that need to review electrical circuits can view the animated tutorial at http://science5.greenlearning.ca/

In order to reduce materials cost, students can be assigned to work in teams of two to four.

1. Start the lesson by having students watch the Science Friday Video, “Creating A Living Building.” Ask students what they see on the roof of the Living Learning Center building. Have students give examples of other solar-powered products or items that they have seen in their daily lives.

2. Inform students that they will be exploring how solar panels work and creating a model of a solar-powered house.

Activity 1 – Solar Panel Exploration

1. Distribute one mini-solar panel, four insulated wires with alligator clips and two light bulbs (with their socket bases) to each team of students. Have students examine their solar panels and discuss their observations.

2. Challenge students to use each solar panel to power a light bulb using a simple circuit. Have students explain how they are able to make the bulb light up. Where is the electricity coming from? Where did they have to place their solar panel in order to generate electricity?

3. Challenge students to power two light bulbs in a series circuit. Have students explain how the connection was made. Do both bulbs light up with the same brightness?

4. Challenge students to power two light bulbs in a parallel circuit. Have student explain how this connection is made. Do both light bulbs light up with the same brightness?

Activity 2 – Building A Solar House

1. Hand out a shoebox to each team of students. Challenge students to wire each house with a light bulb inside that is powered by the solar panel. Students can use scissors to punch holes in the shoebox to run the wires, and electrical tape to hold the wires and light bulb in place.

2. Once students have completed their houses, have them expose the solar panel to sunlight. Does the bulb light up the inside of the house? Remove the house and solar panel from the sunlight. Does the light remain on? How long does it take for the light bulb to turn off?

3. Have students test the following variables:

• a. Tilt the solar panel at various angles. Does the tilting affect the light bulb’s performance?
• b. How much time passes between the solar panel’s direct exposure to sunlight and the light bulb’s turning on?
• c. Does the solar panel work on a cloudy day or in the shade?
• d. Can the solar panel power two light bulbs inside the house?

4. Discuss with students what they have found out from their observations about the advantages and disadvantages of using solar energy. Have students create a list of the challenges of using solar energy, and then discuss possible methods for solving these problems. For example, could they use rechargeable batteries to store energy to rely on when sunlight is not available?

What’s Happening?
Solar panels are made of photovoltaic (PV) cells that convert light energy into electrical energy. In the PV cell, energy from sunlight causes negatively charged electrons to move to the top of the cell, while more positively charged protons remain in place. This movement causes one side of the cell to be mostly negative and the other to be mostly positive, similar to a battery. This movement also energizes the cell to instantly create an electrical current when a complete circuit is connected to the solar panel. However, the movement of electrons only continues as long as the PV cell is exposed to sunlight. PV cells themselves cannot store energy for later use. Battery chargers are often used with solar panels to store and provide energy when there is no sunlight available.

There are many advantages to using solar energy. It is a renewable source that does not release pollutants into the environment. It is free and accessible to all. But there are some disadvantages: buying and installing solar cells can be expensive, and solar power cannot be generated during the night. However, even though initial costs may be high, the overall expenses saved by using solar energy are much higher. With battery chargers, solar energy can be stored to power electrical appliances during the night.

Topics for Science Class Discussion
• What are some of the advantages/disadvantages to using solar energy, as opposed to more traditional sources of energy such as oil, coal, or natural gas?
• Why do houses or buildings have more than one solar panel on their roofs?
• Why haven’t solar-powered cars entirely replaced gasoline- powered cars?

Extended Activities and Links
Extend this activity by having students construct a four-room house with additional appliances that use solar power. A four-room house can be created using a cardboard box and two cardboard pieces with slits to form a T-shape inside the box. Additional appliances can include mini-light bulbs to light each room and a buzzer to act as a doorbell.

Have students research other alternative forms of energy, including biomass, geothermal, hydropower, and wind power. Have students present their findings to the class.

Build a solar cooker that can make water safe to drink:
http://www.pbs.org/wgbh/nova/teachers/activities/3406_solar.html

Design a net-zero energy classroom:
http://www.teachengineering.com/view_activity.php?url=http://www.teachengineering.com/collection/cub_/activities/cub_zero_energy/cub_zero_energy.xml

Explore an interactive animation on solar energy:
http://www.tucsonelectric.com/community/educationalservices/solar/frameset.htm

Report on schools that are using solar energy:
http://www.solarschools.com/

This lesson plan was created by the New York Hall of Science in collaboration with Science Friday as part of Teachers Talking Science, an online resource for teachers, homeschoolers, and parents to produce free materials based on very popular SciFri Videos to help in the classroom or around the kitchen table.

The New York Hall of Science is a science museum located in the New York City borough of Queens. NYSCI is New York City's only hands-on science and technology center, with more than 400 hands-on exhibits explore biology, chemistry, and physics.