Harnessing direct solar energy – a progress report

Activity 4

The cost of solar energy

Although no-one has to pay for sunshine, people often do not use solar energy because they think it is too expensive.

  • Write a short essay discussing the statement: Sunshine is free; solar energy is not.

Teachers notes

Students' answers should cover the costs involved in collecting solar energy, for example:

  • The purchase of photovoltaic cells. They are still costly because of the materials used in them and because they are not manufactured on a large scale.

  • The installation and connection of photovoltaic cells. The installation is often expensive because of the area of cells required (because of the low power density of solar radiation) and the fact that correct orientation is essential.

  • The purchase of storage batteries.

  • Photovoltaic cells produce direct current electricity at low voltage (about 1 volt) like ordinary torch batteries. For many domestic uses this direct current must be converted to alternating current at 240 volts.

  • The price differential between solar and mains electricity. This depends on the price of mains electricity. An important and controversial point is whether mains electricity is fairly priced. Environmentalists claim that its price is unrealistically low and does not take into account the hidden environmental costs. Thus, solar is unable to compete on a level playing field.

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Posted February 1997.