Solar Cells

A solar cell is defined as an electrical device which converts the light energy due to the photovoltaic effect directly into electricity, which is a physical as well as chemical phenomenon.

Solar cell is a type of photoelectric cell which is defined as a device having electrical properties like current, voltage, or resistance change when exposed to the light. Solar cells are the main component of photovoltaic modules, also called solar panels.

Construction of Solar Cell

A solar cell is a junction diode but the construction of a solar cell is somewhat different from the pn junction diodes. A very thin layer of p-type semiconductor grows on a thicker n-type semiconductor. Then apply a fine electrode on the top of the layer p-type semiconductor.
These electrodes do not block the light from reaching the p-type thin layer. A pn junction is there just below the layer of p-type. We also give an electrode for current collecting at the bottom of the layer of n-type. We encapsulate the whole assembly with a thin glass to protect or save the solar cell from mechanical shock.

Solar Cell Working

When light hits the p-n junction, light photons can easily enter the junction through a very thin p-type layer. Light energy in the form of photons delivers enough energy to the junction to create multiple pairs of electron holes. The thermal equilibrium state of the junction is broken by the incident light. Free electrons in the depletion region can quickly find their way to the n-type side of the junction.

In the same way, holes present in the depletion layer can rapidly reach the p-type side of the junction. When the newly generated free electrons reach the n-type side, then they cannot cross the junction any further due to the barrier potential of the junction.

In the same way, newly created holes, once they reach the p-type side, can no longer cross the junction and due to the same barrier potential of the junction. When the electron concentration increases on one side, that is the n-type side of the junction and the hole concentration on another side, that is the p-type side of the junction, the p-n junction behaves like a small battery cell. A voltage is established which is termed as the photovoltage. When we connect a small load across the junction, then a small current will flow through it.

Materials Used in Solar Cell

Commonly used materials in solar cells are given below.

1. Silicon
2. GaAs
3. CdTe
4. CuInSe₂

Criteria for Materials Used in Solar Cell

1. Material which is used in solar cells should have the range of band gap from 1ev to 1.8ev.
2. Material which is used in solar cells should have high optical absorption.
3. Material which is used in solar cells should have high electrical conductivity.

Uses of Solar Cell

There are many uses of solar cell which are given below.

1. Solar cells are used in calculators.
2. Solar cells are also used for transportation.
3. Solar cell is used as a panel for electricity.
4. Solar cell is also used to charge the battery.
5. Solar cells are used in spacecraft as a source of electricity.

Solar cell for Transportation

Solar energy is also used in cars nowadays. This solar energy is generated by photovoltaic cells. Ed Passerini was the first one to build a car which worked on solar cells. The first powered car was manufactured in 1977.

Solar Cell Panel

Solar panels are kept on the roof. It works as a solar heater that heats water. This water can be used for the purpose of bathing. It also has another benefit: it helps with energy production which is used in case of power failure problems. Or people can store this energy and use it to produce electricity at home and save money by lowering the bills of electricity.

Disadvantages of Solar Cell

There are many disadvantages of solar cell which are given below

1. The cost of installation of solar cells is expensive.
2. The efficiency of solar cells is very low.
3. The solar cells cannot produce energy on cloudy days.

Conclusion

A solar cell is defined as an electrical device which converts the light energy due to the photovoltaic effect directly into electricity, which is a physical as well as chemical phenomenon.

A solar cell is a semiconductor which contains pn junctions.

In solar cells, protons and electrons causes the generation of electricity.

Commonly used materials in solar cells are given below.

1. Silicon
2. GaAs
3. CdTe
4. CuInSe2

There are many uses of solar cells which are given below.

1. Solar cells are used in calculators.
2. Solar cells are also used for transportation.
3. Solar cell is used as a panel for electricity.

There are many disadvantages of solar cell which are given below

1. The cost of installation of solar cells is expensive.
2. The efficiency of solar cells is very low.