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Science

Generating electricity

Solar energy

You should be able to outline how solar energy is used to generate electricity and to produce hot water.

Solar cells

a motorist buying a ticket from a solar-powered ticket machine

Solar-powered ticket machine

Solar cells are devices that convert light energy directly into electrical energy. You may have seen small solar cells in calculators. Larger arrays of solar cells are used to power road signs in remote areas, and even larger arrays are used to power satellites in orbit around Earth.

Solar panels

Solar panels do not generate electricity, but rather they heat up water. They are often located on the roofs of buildings where they can receive heat energy from the sun. The diagram outlines how they work.

Cold water is pumped up to the solar panel, there it heats up and is transferred to a storage tank.

A pump pushes cold water from the storage tank through pipes in the solar panel. The water is heated by heat energy from the sun and returns to the tank. In some systems, a conventional boiler may be used to increase the temperature of the water.

cold water is pumped up to the solar panel, there it heats up and is transferred to a storage tank

Solar panel

Advantages

Solar energy is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced.

Disadvantages

  • Solar cells are expensive and inefficient, so the cost of their electricity is high.
  • Solar panels may only produce very hot water in very sunny climates, and in cooler areas may need to be supplemented with a conventional boiler.
  • Although warm water can be produced even on cloudy days, neither solar cells nor solar panels work at night.

Back to Energy and electricity index

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