Principle of Solar Cells

Solar cells are expensive and are used only when supplying electricity becomes difficult.

Solar cells are the devices where solar energy is directly converted into electricity. Solar cells are used in spacecrafts, radios, television, refrigerators, buoys and other navigation aid.

Solar Cell

Sunlight can be used to run machinery and generate electricity. In photovoltaic cells, electricity is produced when light is incident on photosensitive materials. Even though they are costly today they will become cheaper to make when new methods are invented. The cost making the solar cells is expected to decrease, when new methods are invented in future.

About hundred years ago it was found that when sunlight falls on a thin layer of selenium electricity is produced. But the efficiency of the conversion was low (as low as 0.6%). Solar cells were not popular for a long time because of its low efficiency.

The first practical solar cell was constructed in 1954 with an efficiency of 1%. Today we have selenium based solar cells with an efficiency of 25%.

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Principle Underlying the Working of a Solar Cell

Principle Underlying the Working of a Solar Cell

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Semiconductors whose conductivity is more than insulators and less than metals are used in electronic devices. The conductivity of the semiconductors increase when light falls on it. Wafers of doped semiconductors are so arranged that when sunlight falls on the arrangement, potential differences are developed and the energy is stored. This forms the solar cell. The energy developed is proportional to the surface area of the wafer exposed to light. The efficiency of the solar cells made from semiconductors is around 10% to 15%.

Here a number of solar cells are arranged so that, the potential difference developed is the sum of the potential difference developed across the individual ones. These solar panels are used mostly in remote and isolated areas.