Solar energy

Self-service parking pay station with solar power
A solar-powered ticket machine

Solar energy is used to generate electricity and to produce hot water. Solar energy is energy released by nuclear fusion in the Sun.

Solar cells (photovoltaic)

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 the 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.

Diagram showing how a solar panel heats water. The diagram shows a solar panel, a water pump, a hot water storage tank and a boiler.

Cold water is pumped up to the solar panel. Then 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.

Advantages of solar energy

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

Disadvantages of solar energy

  • Solar cells are expensive and inefficient, so the cost of their electricity is high.
  • Solar cells do not work at night.
  • 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, solar panels do not work at night.