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Solar Cell

The name Solar Cell means that it is a cell or a plate which converts solar energy into the useful electrical energy. The energy which we get from sun is enormous and it is a great source of energy. Its energy will never finish so this is also known as as the main source of renewable energy. With the scarcity of non-renewable energy it is of utmost importance to find a way out to solve the energy problem by some means within a very short period of time. So there is a way out which is now developing. That is we are now able to convert the sun energy to electrical by some means and that is why the importance of solar cell comes into play. Though it is developing but if it is developed completely, then every household may produce the energy of its own.The solar cell is a device which is made of p-n junction diode which effect photo voltaic effect to convert light energy into electrical energy.

Construction of Solar Cell

The junction diode is made of SI OR GaAs. A thin layer of p-type is grown on the n-type semiconductor. Top of the p-layer is provided with a few finer electrodes which leaves open space for the light to reach the thin p-layer and it under lays p-n junction. Bottom of the n-layer is provided with a current collecting electrode. solar cell

Working Principle of Solar Cell

When light reaches the p-n junction, electron is excited to the valance band under the condition that light energy is higher than the band gap energy, it generates the electron and holes which are equal in number in the valance and conduction band respectively. These electron hole pairs move in opposite directions to the barrier field. Electrons move towards the n-side and the hole is moved towards the p-side. So a voltage is set up which is known as photo voltage and when a load is connected, the current flows.

V-I Characteristics of a Photovoltaic Cell

v-i characteristics of a photovoltaic cell

Materials Used in Solar Cell

The materials which are used for this purpose must have band gap close to 1.5ev. Commonly used materials are-
  1. Silicon.
  2. GaAs.
  3. CdTe.
  4. CuInSe2

Criteria for Materials to be Used in Solar Cell

  1. Must have band gap from 1ev to 1.8ev.
  2. It must have high optical absorption.
  3. It must have high electrical conductivity.
  4. The raw material must be available in abundance and the cost of the material must be low.

Advantages of Solar Cell

  1. No pollution associated with it.
  2. It must last for a long time.
  3. No maintenance cost.

Disadvantages of Solar Cell

  1. It has high cost of installation.
  2. It has low efficiency.
  3. During cloudy day, the energy cannot be produced and also at night we will not get solar energy.

Uses of Solar Generation Systems

  1. It may be used to charge batteries.
  2. Used in light meters.
  3. It is used to power calculators and wrist watches.
  4. It can be used in spacecraft to provide electrical energy.

Conclusion: Though solar cell has some disadvantage associated it, but the disadvantages are expected to overcome as the technology advances, since the technology is advancing, the cost of solar plates as well as the installation cost will decrease down so that everybody can effort to install the system. Furthermore, the government is laying much emphasis on the solar energy so after some years we may expect that every household and also every electrical system is powered by solar or the renewable energy source.

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