Cooling by Solar Energy

  • Can solar energy be used to run a fan to cool a house instead of wall electricity?
  • How long would a solar-energy-run fan have to run each day (all the time night and day, or just during the day)?
  • Is it economical?
  • What is the advantage of solar power?
  • What solar cells would be better to use to power the cooling fan, (poly silicon cells, single crystalline silicon cells, etc.)

Recommended Items:

  • Solar panels
  • Fan
  • Voltmeter
  • Batteries

Concepts used:

  • Materials, Electricity, Optics, Economics


Solar cells are devices that absorb light energy and convert it into electrical energy. Electricity flows through materials from negatively rich areas to positively rich areas, and this flow of electrons is called current. To guide the current from the solar cell to an external load, such as a light bulb or a fan, a circuit is set up. A black wire is typically connected to the negatively rich part of the cell and a red wire is connected to the positively rich part of the cell. Then each of those wires is connected to an external load, which is the device that needs electricity to run.

Semiconductors are interesting materials because they have special properties. Like metals they have free electrons that can move through the material. However, unlike metals there are fewer free electrons. In the case of solar cells, light from the sun or a powerful lamp is absorbed, freeing up more electrons and creating electricity. Also like metals, semiconductors can give up electrons or receive electrons depending on whether they are more negatively or positively rich.

In this experiment, a fan is used to cool a house or enclosed area. One possible way of comparing the cost of wall electricity to the cost of a solar cell is to compare the cost of running a fan from a wall outlet to the cost of running a fan using a solar cell. Plug a fan into the wall and monitor how the consumption of power changes on the electric meter located outside your home. In order to do this you will need to turn off as many appliances as possible inside the house and monitor the rate of power consumption (how many Watts are used in a 10-30 minute period) without the fan plugged in and compare that to the rate of power consumption while the fan is plugged in and running. Then attach a solar cell to the fan and see how it operates. Does it run as quickly? Does it cool as effectively? By comparing the price of electrical energy used to power the fan using electricity from the wall plug to the cost of the solar cell it is possible to look at the economics of solar power. Keep in mind that solar cells only run during the day time unless they use batteries to store energy for night time use. Also, different types of solar cells can be purchased to compare to one another.

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