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Solar Cell: Test Your Understanding
Teacher's Guide
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1. Describe the energy conversion that takes place inside a solar cell.
Solar cells convert light energy into electrical energy when light is absorbed by a
semiconductor material.
2. What is a pn junction?
A pn junction is an electrical junction formed by the contact of two semiconductor regions. It
consists of an interface between p-type silicon, which carries the holes, and n-type silicon, which
carries the electrons.
3. Critical Thinking: Suppose you observe that the semiconductor material in a faulty solar cell has an
excess of positive holes. However, no current is being generated. What part of the solar cell is likely
to be defective?
The electrical junction, which separates electrons from positive holes to generate a current, is likely to
be defective. Separation of positive and negative charges is required for electrical generation.
4. Critical Thinking: A solar panel array provides an off-grid homeowner with 100 amp current at 120 volts.
How can the homeowner power a clothes dryer that requires 220 volts?
The homeowner can connect some of the panels in series to increase the output voltage.
5. Critical Thinking: Compare the energy output of a solar panel on a satellite to the same type of panel on
farmland in the midwestern U.S. What factor affects output?
Output will depend on the amount of solar energy absorbed, which will be greater for the panel on the
satellite due it being outside of Earth's atmosphere. The air, as well as clouds, reduces the intensity of
incident light on the ground.
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