Question

Solar cells, also called photovoltaic cells, convert the sun’s energy into electricity. Solar cells have no moving parts, and they run on nonpolluting power from the sun. So why don’t solar cells meet all our energy needs? A solar cell produces a very small electrical current. Meeting the electricity needs of a small city would require covering hundreds of acres of land with solar panels. Solar cells also require extended periods of sunshine to produce electricity. This energy is stored in batteries, which supply electricity when the sun is not shining. Despite these limitations, the demand for electricity from solar energy has grown about thirty percent per year over the past twenty years.

Solar cells are becoming increasingly efficient and less expensive. Solar cells have great potential for use in developing countries, where energy consumption is minimal and electricity distribution networks are limited. Currently, solar cells provide energy for more than three million households in the developing world.

IDENTIFYING MAIN IDEAS:

In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question.

1. Solar cells convert the sun’s energy into

a. light. b. heat.

c. electricity. d. pollution.

2. Solar cells have great potential for use in

a. cities. b. private homes.

c. factories d. developing countries.

RECOGNIZING SIMILARITIES AND DIFFERENCES:

Read the following questions and write the answers in the space provided.

3. How are solar cells different from most other power sources?

a.

4. How are solar cells of today superior to solar cells that were produced 20 years ago?

a.

VOCABULARY DEVELOPMENT:

In the space provided, write the letter of the definition that best matches the term or phrase.

_____ 5. photovoltaic cells

_____ 6. solar panels

_____ 7. energy consumption

_____ 8. batteries

a. power usage

b. store energy collected by solar cells

c. convert the sun’s energy into electricity

d. collections of solar cells

RECOGNIZING CAUSE AND EFFECT:

Read the following questions and write the answers in the space provided.

9. Why are solar cells particularly suitable for developing countries?

a.

10. Why aren’t solar cells used to meet all of our energy needs?

Answer 1

1. c

2. d

3. Solar cells have no moving parts and produce nonpolluting electricity directly from the sun (unlike most conventional power sources).

4. Today's solar cells are more efficient and less expensive than those produced 20 years ago.

5. c

6. d

7. a

8. b

9. They work well where energy use is low and electric distribution networks are limited — solar systems can provide off‑grid power without needing extensive infrastructure.

10. Because each cell produces only a small current, meeting large demands would require vast areas of panels; they also need extended sunshine and batteries for storage (they’re intermittent), which limits their ability to meet all energy needs.