What is Solar cell?
Solar cell is also called as photovoltaic cell and this is a device which converts light energy into electrical energy by using photovoltaic effect. Solar cell is basically a normal PN Junction diode.
Symbol of Solar cell:
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| Symbol of Solar Cell |
Construction of Solar cell:
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| Construction of Solar cell |
It consists of N type and P type semiconductor material. N type is highly doped and P type is lightly doped. Top and bottom is of conducting electrode to collect the current. The bottom is fully covered with the conductive layer and top layer is not fully covered because the sun rays should not be fully blocked. Since semiconductors are reflective in nature, antireflective coating is used. The whole arrangement is kept inside a thin glass to avoid mechanical shock.
Working of Solar cell:
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| Working of Solar cell |
The working of solar cell is based on photovoltaic effect. It is a effect in which current or voltage is generated when exposed to light. Through this effect solar cells convert sunlight into electrical energy.
A depletion layer is formed at the junction of the N type and P type semiconductor material. When light energy of the sun rays falls on the solar panel, the photons which is the small bundle of energy whose energy is higher than the energy gap gives energy to the electrons and holes in the depletion region. The electrons and holes move to the higher level which is the conduction band. The electrons move towards N type and holes move towards P type and they act as a battery. So this movement of electrons and holes forms the electric current.
Solar cell to Solar farm:
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| Solar cell to Solar farm |
Solar cell is the basic building module and it is in octagonal shape and in bluish black colour. Each cell produces 0.5 voltage. 36 to 60 solar cells in 9 to 10 rows of solar cells are joined together to form a solar panel. For commercial use upto 72 cells are connected. By increasing the number of cells the wattage and voltage can be increased. The thickness of solar panel is in the range 2.5 to 4cm. Many modules together form the solar array.
V-I characteristics of Solar cell:
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| V-I characteristics of Solar cell |
Isc is the short circuit current and it is measured by short circuiting the terminals. Voc is the open circuit voltage and it is measured when no load is connected. Pm is maximum power, Im is maximum current, Vm is maximum voltage and it occurs at the bend of the characteristic curve.
Advantages of Solar cell:
• It uses renewable energy
• No pollution so it is environment friendly
• It lasts for many years
• No maintenance cost
Disadvantages of Solar cell:
• Energy is not produced during rainy, cloudy days and during night times.
• Cost of installation is high.
Applications of Solar cell:
• It is used in calculators and in wrist watches
• Used in storage batteries
• Street lights
• Portable power supplies
• Satellites
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