© boardworks ltd 20061 of 39 the then and now guide to solar energy how has the use of solar energy...

© Boardworks Ltd 20061 of 39

The then and now guide to solar energy

How has the use of solar energy changed over time?


How much energy comes from the Sun?

The Sun is a huge sphere of very hot gas and has been producing energy for millions of years.

Solar energy is the radiation from the Sun that reaches Earth. It powers photosynthesis in green plants and is ultimately the source of all food and fuel.

Even though it is about 150 million kilometres away, the Sun is our closest star and sustains all life.

The amount of solar energy that strikes the Earth each day is 10,000 to 15,000 times greater than our daily energy needs.

In fact, the Sun is so powerful, that every minute, enough solar energy reaches Earth to meet our needs for one year!


Buildings can be designed to allow in as much light as possible, by incorporating glass walls instead of solid walls. The building is then heated by utilizing the greenhouse effect, which reduces additional energy needs and costs.

How can the Sun heat buildings?

This low energy house not only has a photovoltaic roof but also has been designed so that it requires only a minimum amount of energy for heating and lighting.

maximize access to the Sun.

The house is orientated in an east-west direction and the rear is south-facing to


How does a greenhouse capture solar energy?


Greenhouse effect – ordering activity


Solar power stations use the Sun’s energy to heat water and make steam, which then drives a turbine to produce electricity.

Some solar power stations use a series of mirrors, called heliostats, to reflect light onto a boiler.

© Sandia National Laboratory/NREL

What is a solar power station?

This solar power station in California consists of about 1800 heliostats, with an electrical output of 10 megawatts.


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.

More solar power stations


Solar power stations are most effectively located in areas with high light intensity.

Making solar power stations effective

This test design is located in Arizona where the sunlight is intense and the air temperature is high.

The mirrors must track the Sun as it moves across the sky, to be as efficient as possible.

Would this sort of power station be effective in the UK?


Solar cells (or photocells) turn light energy from the Sun directly into direct current electricity.

Solar cells are ideal for use in remote locations where maintenance is difficult and other sources of electricity would be expensive.

Why use solar cells to power satellites?

Manufacturing solar cells is very expensive and requires the use of highly toxic materials. However, once the solar cell is built it produces no pollution and requires little maintenance.

Satellites have been powered using solar cells since the 1950s.


How do solar cells work?


Solar cells suffer from a low efficiency. This is because only light with enough energy causes electrons to be released, which is only about 25% of all sunlight.

The amount of electricity a solar panel can produce depends on two factors: its surface area and the light intensity.

How well do solar cells work?

Producing enough electricity to power a town would require a very large area of solar panels but covering the roof of a house can meet the annual electricity needs of thehousehold.


One obvious problem with solar cells is that they do not produce electricity at night.

What are the problems with solar cells?

Scientists are working to develop improved solar cells, which require less polluting chemicals in their manufacture, cost less to produce and are more efficient than thecurrent technology.

If more electricity is produced during the day than is used, the excess can be used to charge a battery. This can then provide power during the night.


What are solar cells used for?

Solar cells are very useful where the light intensity is highest.

Solar cells are also useful where low amounts of power are needed.

in place of batteries .

These solar panels are in a remote part of Morocco where they are used by a local utility company.

Calculators only require a small amount of electricity, so most calculators now use solar cells


Solar cells are very useful for remote locations where supplying mains electricity would be expensive.

Why use solar cells in remote areas?

This solar-powered street light is in a remote part of mid-Wales with no mains electricity supply close by.

The use of solar power in this way removes the need to lay electricity cables to the light, which is another benefit to the environment.


Pros and cons of solar cells


Solar cells – true or false?

© boardworks ltd 20061 of 39 the then and now guide to solar energy how has the use of solar energy...

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