Solar cells convert sunlight into electrical energy through the photovoltaic effect. They are constructed of layers of n-type and p-type semiconductors that form a p-n junction. When sunlight is absorbed, electrons are freed and produce an external DC current. There are three main types of solar cells: monocrystalline silicon cells have the highest efficiency around 14-17%; polycrystalline silicon cells have an efficiency of 13-15%; and amorphous silicon cells have the lowest efficiency of 5-7%. Solar cells have advantages of being renewable, clean, and requiring little maintenance but their initial costs remain high.
2. Contents
β’ Introduction
β’ Principle of Solar Cell
β’ Construction of Solar Cell
β’ Working of Solar Cell
β’ Types of Solar Cell
β’ Generation of Solar Cell
β’ Advantages & Disadvantages of Solar Cell
β’ Applications of Solar Energy
3. Introduction
β’ Solar cell is the photovoltaic device that convert the light energy
(which come from sun) into electrical energy.
β’ This device work on the principle of photovoltaic effect.
β’ Photovoltaic Device:- The generation of voltage across the PN
junction in a semiconductor due to the absorption of light radiation is
called photovoltaic effect. The Devices based on this effect is called
photovoltaic device.
4. Principle of Solar Cell
β’ The solar cells are based on the principles of photovoltaic effect. The
Photovoltaic Effect is the photogeneration of charge carriers in a light
absorbing materials as a result of absorption of light radiation.
5. Construction of Solar Cell
β’ Solar cell (crystalline Silicon) consists of a n-type semiconductor
(emitter) layer and p-type semiconductor layer (base). The two
layers are sandwiched and hence there is formation or p-n junction.
β’ The surface is coated with anti-refection coating to avoid the loss of
incident light energy due to reflection.
β’ A proper metal contacts are made on the n-type and p-type side of the
semiconductor tar electrical connection.
6. Working of Solar Cell
Working
β’ When a solar panel exposed to sunlight
the light energies are absorbed by a
semiconductor materials.
β’ Due to this absorbed energy, the
electrons are liberated and produce the
external DC current.
β’ The DC current is converted into 240-
volt AC current using an Inverter for
different applications.
7. Comparison of Types of solar cell
Material Efficiency (%)
Monocrystalline silicon 14-17
Polycrystalline silicon 13-15
Amorphous silicon 5-7
8. Generation of Solar Cell
First Generation-single Junction Silicon Cells
β’ Limit efficiency 31%
β’ Single crystal silicon - 16-19%
efficiency
β’ Multi-crystal silicon - 14-15%
efficiency
β’ Best efficiency by Sun Power 22%
οΌ87.4% of 2007 Production
οΌ45.2% Single Crystal Si
οΌ42.2% Multi-crystal SI
9. Second Generation- Thin Film cells
β’ New materials and processes to improve
efficiency and reduce cost.
β’ Thin film cells use about 1% of the expensive
semiconductors compared to First Generation
cells.
β’ Single Crystal Si 4.7% & multi Crystal Si 0.5%
of 2007 Production
β’ Single Crystal Si has 8-11% efficiency.
β’ Multi Crystal Si has 7-11%
efficiency.
10. Third Generationβ Multi-junction Cells
β’ Enhance poor electrical performance while maintaining very low production costs.
β’ Current research is targeting conversion efficiencies of 30-60% while retaining low cost materials
and manufacturing techniques.
β’ Multi-junction cells β 30% efficiency (4043% demonstrated)
11. Types of Solar Cell
οΆ Based on the types of crystal used, soar cells can be classified as,
1. Monocrystalline silicon cells
2. Polycrystalline silicon cells
3. Amorphous silicon cells.
1. The Monocrystalline silicon cell is produced from pure silicon (single crystal). Since the
Monocrystalline silicon is pure and defect free, the efficiency of cell will be higher.
2. In polycrystalline solar cell, liquid silicon is used as raw material and polycrystalline silicon
was obtained followed by solidification process. The materials contain various crystalline sizes.
Hence, the efficiency of this type of cell is less then Monocrystalline cell.
12. 3. Amorphous silicon was obtained by depositing silicon film on the
substrate like glass plate.
οThe layer thickness amounts to less then 1Β΅m-the thickness of a
human hair for comparison is 50-100 gm.
οThe efficiency of amorphous cells is much lower then that other two
call types.
οAs a result, they are used mainly in low power equipment, such as
watches and pocket calculators, or as façade elements.
13. Advantages of solar cell
β’ It is clean and non-polluting.
β’ It is a renewable energy.
β’ Solar cells do not produce noise and they are totally silent.
β’ They require very little maintenance.
β’ They have long life time.
β’ There are no fuel costs or fuel supply problems.
14. Disadvantages
β’ Soar cells (or) solar panels are very expensive.
β’ Energy has not be stored in batteries.
β’ Air pollution and whether can affect the production of electricity.
β’ They need large are of land to produce more efficient power supply.
β’ Sun does not shine consistently.
β’ Less efficient and costly equipment.
β’ Reliability Depends On Location.
15. Applications of solar energy
β’ Domestic power supply.
β’ Electric power generation in space.
β’ Drying Agricultural Products.
β’ Solar pumps are used for water supply.
β’ Water Heating.
β’ Generating Electrical Power.
β’ To providing electrical power to satellites.
