ONE MILLION STUDENTS

Lesson 1: Solar Energy Explained

AGENDA

• The Sun• Nuclear Fusion• Solar Energy on Earth• Photovoltaics• Electricity from the Sun• Review• Solar Application Stories• Energy Action Checklist

THE SUN

• The sun is a big gas ball made up mostly of hydrogen and helium atoms.

• Every second, the SUN radiates an enormous amount of energy out into space.

• This energy comes from within its inner core in a process called nuclear fusion.

What Is Solar Energy?

• The temperature and pressure break up the hydrogen into nuclei.

• 4 hydrogen nuclei form to make one Helium atom.

• During the fusion process, radiant energy is produced which we see in the form of sunlight.

Nuclear Fusion

What Is Solar Energy?• It take millions of years for the radiant

energy in the suns core to make its way to the solar surface.

• It takes a little over eight minutes for the solar energy to travel to earth.

• The radiant energy travels to the earth at a speed of light, 186,000 miles per second. That’s 90 million miles in 8 minutes.

SOLAR ENERGY ON EARTH

• Only a tiny portion of the energy from the sun strikes the earth. Yet this amount of energy is enormous.

• In one day enough energy strikes the United States to supply the nation’s energy needs for one and a half years.

SOLAR ENERGY ON EARTH

• The 51% of radiant energy that hits the earth can be used as a source of energy.

• The energy can be captured using a photovoltaic cell.

• Photovoltaics: comes from the words photo meaning light, and volts, which is a measurement of electricity.

• Photovoltaic cells are also known as PV cells or solar cells.

PHOTOVOLTAICS

What are PV cells made of?• Solar cells are made of two thin pieces of silicon.

• Each cell has a positive and a negative layer.

• Positive-layer: is the piece of silicon that has a small amount of boron added to it, which gives it a tendency to attract electrons, hence has a positive tendency.

• Negative-layer: is the piece of silicon that has a small amount of phosphorous added to it, giving it an excess of free electrons. This is why it has a tendency to give up electrons, a negative tendency.

PHOTOVOLTAIC CELLS

• When the two pieces of silicon are placed together, some electrons form the n-layer flow to the p-layer and an electric field forms between the layers.

• When the PV cell is placed in the sun, the radiant energy energizes the free electrons.

• This movement causes energy which can be used as electricity. This happens silently and instantly.

ELECTRICITY FROM THE SUN

Protective Glass

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-Conductive Backing

P-Type Silicon

N/P Junction

N-Type Silicon

Conductive MeshAnti-Reflective Coat

Photons from the Sun

Flow of EnergyOr Load

USING THE SUN TO WORK

These all use the sun to work.

Review Questions:1. How many people lack access to electricity around the world?

1.3 billion people

2. What are some of the benefits of Solar lighting?

a. Higher Productivityb. Increase Incomec. Savingsd. Decrease in respiratory diseasese. Additional study hours for students

3. Why should we use solar?

a. The sun will not “run out”. It is renewable and will last a long time.b. The sun is eco-friendly and does not harm the Earthc. There are no carbon emissions that are leading to global warmingd. The sun is easily accessible and availablee. The sun is clean and healthy. It does not harm human beings with toxic fumes

SOLAR APPLICATION ACTIVITY

1. Find a partner or 2.

2. Come up and grab a solar light, worksheet and a solar story

3. In your team read the story using the solar light and answer the questions.

4. Be prepared to share your story with the rest of the class.

5. When you finish one story, please return it to me and grab another one. Ideally we want each group to read 2 different stories.

Class Presentations and Discussion

Energy Action Checklist!

CONSERVE ENERGY

1. Turn off the lights or heating when not in use.2. Turn off entertainment devices when not in use (TV, game systems).3. Unplug your phone charger and other appliances when not in use.4. Use energy saving light bulbs.5. Shut down computer.6. Use “smart” power strips.7. Use natural light, heat and cooling.8. Talk to your parents about energy saving appliances for your home; programming digital thermostats and about making home improvements. (windows, doors)11. Take shorter showers, close the water tap when not in use.12. Avoid a flight or a driving trip when it is not essential.

LIMIT YOUR IMPACT1. Ride a bike/bus/train instead of driving the car and ride-share2. Replace an old refrigerator and other appliances with energy efficient ones3. Replace a big car with a more efficient model4. Take lunch instead of purchasing takeout5. Insulate the water heater6. Insulate the house with better windows and air seal the house7. Recycle and buy recycled goods8. Choose Organic9. Calculate your footprint10. Market your products online instead of on paper