Solar Energy We can use the sun’s energy every day.

Solar Energy

We can use the sun’s energy every day.

The sun is a giant ball of gas. It sends out huge amounts of energy

every day.

Nuclear Fusion

• The Sun is made up mostly of hydrogen and helium.

• It makes energy in its inner core in a process called nuclear fusion.

Solar Radiation

Every day the sun radiates (sends out) an

enormous amount of

energy.

Solar Energy travels from the sun to the earth in rays.

Some are light rays that we can see. Some we can’t see, like x-

rays.

• Plants use the light from the sun to grow.

• Plants take the energy in light and store it in their roots and leaves.

• The energy feeds every living thing on earth.

Plants Depend on Solar Energy

We Depend on Solar Energy

• Sunlight turns into heat when it hits things. Without the sun we couldn’t live on earth- it would be too cold.

• All day, we use sunlight to see what we’re doing and where we’re going.

Heating water and drying clothes

Warming our homes

We Use Solar Energy For:

Generating electricity.

A solar collector is one way to capture sunlight and change it into usable heat.

Solar Collectors

A car on a hot, sunny day becomes a solar collector. The car’s

windows let light in, but they don’t let all the heat out. A closed car

can get very hot!

Solar Collectors

Solar Cells

• Another type of solar collector is a solar cell.

• Solar cells turn light energy into electricity.

Big solar cells can make enough electricity for a

house!

Our houses can use solar cells in two ways:

As Solar Thermal Systems

As Photovoltaic Cells

Solar Thermal Systems• Special collectors that

look like glass are mounted on the rooftop.

• Dark-colored metal plates inside the boxes absorb sunlight and change it into heat.

• Air or water flows through the collector and is warmed by the heat, which is then distributed through the house.

• Solar cells are Photovoltaic cells.

• Photovoltaic comes from photo, meaning light, and volt, a measure of electricity

• Electricity is produced when sunlight strikes the solar cell, causing electrons to move around. The action of the electrons starts an electric current.

Photovoltaic Cells

Examples of photovoltaic cells

are solar-powered

calculators and roadside telephone

call boxes.

Photovoltaic Cells

Solar Energy is Renewable

Solar energy is free and clean!

There is enough for everyone, and we will never run out of it!

Every day enough solar

energy reaches the earth to supply our

nation’s energy needs for a year!

Solar Energy is Renewable

So why don’t we use the sun for ALL our Energy Needs?

We don’t really know how to yet!

The hard part is capturing enough sunlight.

The sun shines all over the earth, but only a little bit reaches any

one place.

On a cloudy day, most of the light never

reaches the ground at all.

Scientists are looking for new ways to capture and

use solar energy.

Right now scientists are studying huge solar power towers as one possible

solution.

The Solar Tower laboratory at the Weizmann Institute of Science

Solar Power Tower

• Solar Power Towers capture sunlight to generate electricity.

• Each tower may have up to a thousand mirrors connected to it!

• Scientists are testing these towers for large-scale power grids.

Discussion Questions

• Do you use solar power at your house?

• Are solar panels cheaper or more expensive to use than electricity generated by coal?

• Do you think Texas is a good area of the United States to use solar power? Why or why not?