For thousands of years, people have designed structures to capture energy from the sun. Architects in Ancient Rome built openings into the ceilings of domed buildings, like the Pantheon, to fill the interior with as much sunlight as possible. The Pueblo structures in the southwest United States are built of stone and thick adobe (sun-dried mud) walls to keep inside temperatures cool during the day while retaining heat at night. Today, we have photovoltaic technology, often in solar panels, to draw energy from the sun and convert it into electrical energy. During this lesson, students will learn how to design and customize electrical circuits to use the power from solar panels, and install it into their own small Solar House.

At the end of the lesson, students will:

Understand and be comfortable with basic electrical concepts and terminology
Understand and be able to build basic circuits
Know the fundamental aspects of a solar panel and understand how placement and orientation affect its efficiency
Be familiar with how solar panels are installed on structures
Be able to use electrical engineering, art, and design skills to build a functioning solar powered electrical circuit
Be able to use the scientific method to isolate and adjust variables in a solar powered house
Build teamwork skills during design, construction, and troubleshooting processes (extension activities)

Step 1: Materials

Here are the Materials you will need for making a Solar House:

Solar panel
2 Double (AA) batteries and battery holder
Switch (optional, since we are going to make our own switch)
LED bulbs
Incandescent bulbs (holiday lights)
Buzzer
Motor
Uncoated wire
Clamp wires
Aluminum tape
Diode (we will not use this for our example)
Box
Index cards
Motor wheel/ propeller
Foam/color cardstock (for decoration)
Some other decoration materials

Tools:

Multimeter
Hot glue gun + glue sticks
Scissors
Rulers

You can buy all the materials above from REchargeLabs's Solar Town kit, http://www.rechargelabs.org/solar-town-class-pack

Or get similar project at http://www.rechargelabs.org/

Step 2: Design Your House

Our design instructions will be very general, since your own design will likely be quite different from this example. This is to give you a basic idea of where to start.

Think about the shape of your house and where you want the electronic and solar panels to be. Make marks on the cardboard where you want to cut, then cut it out to fit your plan.

Step 3: Glue Pieces Together

After cutting out parts of the cardboard box, use the hot glue gun to glue parts into desired positions or to hold pieces together.

Step 4: Initial Decoration

Use color cardstock or decoration materials to add to the house. More decoration will be added later on after we have the wires and electronics put in the house. If you are satisfied with the design, set it aside.

Step 5: Test Your Electronics

Before we move on to do anything else, we want to make sure that the parts are working. You can test your holiday lights, LEDs, buzzers, or motors by connecting each of them directly to the battery pack. LEDs are polarity sensitive, which means the test will not work unless you wire the LED legs (two wires on the LED) to their polarity. Generally, the longer leg on an LED is positive and the shorter leg is negative. In this case, the longer leg of the LED will connect to the red wire from the battery pack and the shorter leg to the black wire.

Step 6: Series and Parallel Circuits: Series Connection

For this step, let's explore what we mean when we talk about series and parallel circuits. When should one use series, parallel or both circuit connections?

When you connect a circuit in series, the voltages of each component are added together and the amp stays the same. For example, look at the battery packs and the solar panels in the image above. They are connected in series. Each battery pack has an output of about 3 Volts. When you combine them by connecting a positive (red) wire from battery pack A to a negative (black) wire from battery pack B, they will output 6 volts in total. However, the amps between the two battery packs do not add up. They stay the same as a single battery pack. Series connection is needed when you have an output that needs more voltage to operate than what one battery pack can provide.

When it comes to outputs (lights, motors, or buzzer) of a circuit in series, the voltage needs are increased. It will need the combined amount of voltages from both components in order for both components to operate properly. Otherwise, the electricity will take the easiest path or go to only one component. If one light is burned out, it will break the circuit and stop the other lights in the series connection.

Step 7: Series and Parallel Circuits: Parallel Connection

For Parallel circuits, the current/amp will add up from the two components that are connected. The voltage in this case will stay the same. A parallel circuit is great for cases where you want to keep the voltage the same to allow your output to stay on for longer without burning out.

For parallel connection, connect the positive (red) wires from both power sources together, and then to the output. Do the same with the negative wires (black).

When you wire an output (light, motor, or buzzer) in parallel (refer to the third pictures), the battery will drain faster since there are three difference outputs connecting in parallel drawing current from the one battery. However, the benefit is that if one light is burn out, it does not break the entire circuit. This means that the other light will still stay lit.

Step 8: Make a Switch

A switch is basically a safe and intentional breakage or interruption in a circuit. Use it when you want to turn something on or off.

Grab a piece of index card and fold it in half as shown. Apply aluminum tape to one side of the index card. Make sure the tape overlaps the edge of the index card, then fold it around to cover the inside part of the index card. Repeat this step on the other side of the index card.

Step 9: Switch Wires

Use clear tape to tape down a wire on each side of the index card. Make sure the wires are on the outside as shown in the pictures.

Step 10: Add a Switch to Your Circuits

Connect the switch by breaking one wire, either the red (positive) or negative (black). Connect it inline with the wire. The circuit is complete when the aluminum tape on the index cards touches. That will turn on the outputs. If the cards do not touch, the circuit is open and does not allow electricity to flow to the outputs.

Step 11: Put Your Electronic Parts on the House

To attach your electronic parts, first make holes for the wire to go out the back of your house. This way it is easier to connect them to the power source. At the same time, decide what connection is right for your application base on the series or parallel connection.

Step 12: Wire the Parts Together

Wire all of your outputs together in series or parallel to the outside and back of the house. This will allow you to switch between different power sources. Connect them to the battery and switch. Test and make sure all the components are working as intended.