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Solar Power

19 April 2023

Objectives

Be able to describe how electricity can be produced directly and indirectly from the Sun’s rays and describe how the

intensity of the Sun effects the output power.HSW: AF5: Working critically with evidence. AF1: Thinking scientifically.

Used before in: Will use again in:

PLTS: Independent enquirers: support conclusions, using reasoned arguments and evidence.

Used before in: Will use again in:

KeywordsLight, heat, infra-red, thermal, photo-voltaic, intensity, precise,

accurate, reliable.

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Outcomes

All students should be able to: Be able to describe that electricity

can be produced from the Sun’s light and heat.

Most students should be able to: Carry out an investigation into how

the voltage of a solar cell varies with light intensity.

Some students should be able to: Evaluate the method used and

suggest improvements. Explain how a photovoltaic cell works.

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Solar Power

• Electricity can be produced by the heating effect of the Sun or by directly transforming light into electricity.

• These are called passive solar heaters.

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Passive solar heating involves any system that can capture the Sun’s energy directly. This can be done using a simple solar collector or by the design of a building.

What is passive solar heating?

For example, the heat of the Sun can be focused on one spot using a curved mirror.

What do you think are the advantages and disadvantagesof passive solar heating?

Solar cookers work on this principle and so require no fuel.

Other examples of passive solar heating include a greenhouse or a south-facing window.

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Solar thermal power stations

• Some solar power stations use curved mirrors, which focus solar energy onto pipes containing water. This heats the water and forms the steam needed to drive a turbine.

• Thermal Towers boil water into steam to turn turbines that drive generators and produce electricity.

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• Demo solar furnace

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• Solar Cells use the light and transform it directly into electricity in a photovoltaic cell. (photo-light; voltaic-voltage making)

• Demo calculator(!)• Demo solar powered car.

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How do solar cells work?

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Butt Head - Explanation

• A solar panel is made of silicon crystal.• An atom of silicon contains a nucleus and

electrons. • Student model• Light is used to raise electrons from lower

energy levels to higher ones.• When electrons are knocked loose, they

flow freely and create an electrical current.

• Photocells tend to be about 25% efficient. • In other words only a quarter of the light

has enough energy to knock the electrons loose to flow freely.

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Pros and cons of solar power

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PRACTICAL TIME!

How does the light intensity affect the voltage output?

MethodSet up the equipment:

Distance (cm)

Voltage (V)

0

7

14

21

28

35

42

49

Analysis:Draw a graph:

d/cm

V/V

The light intensity goes down as the light is further away from the solar cell but does the voltage?

How could you improve the experiment to make it more precise, more accurate, more reliable?

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Plenary: Mark your partners book. Tell them WWW and EBI and give them a grade.

All students should be able to: Be able to describe that electricity can

be produced from the Sun’s light and heat. C

Most students should be able to: Carry out an investigation into how the

voltage of a solar cell varies with light intensity. B

Some students should be able to: Evaluate the method used and suggest

improvements. Explain how a photovoltaic cell works.

A