Solar Cell – Working Principle, Diagram, Efficiency & Applications
Quick Exam Notes
- Definition: A solar cell (photovoltaic cell) converts sunlight into electricity using the photovoltaic effect.
- Working: Photons create electron–hole pairs at the P-N junction, generating current.
- Construction: Made of silicon with metal contacts and an anti-reflective coating.
- Symbol: Diode symbol with arrows showing incident light.
- Efficiency: Depends on material, light intensity, and temperature.
- Applications: Found in solar panels, calculators, satellites, and portable devices.
Principle
The photovoltaic effect is a phenomena in which certain materials generate an electric current when exposed to light. When photons of light are absorbed by a semiconductor material, causing the release of electrons and generating an electric current.
Figure 1: Solar cell diagram illustrating the working principle based on the photovoltaic effect.
Theory
Figure 1 shows a schematic layout of a p-n junction based solar cell. Here the n-region is heavily doped and the n-region is made thin so that maximum sun light can penetrate through n region. When the semiconductor absorbs enough sunlight, electrons are dislodged from the material's atoms, creating holes. Now, due to strong barrier field, the electrons (minority charge carrier) from 'p' type moves towards the 'n' side and similarly holes from 'n' type move towards the 'p'-side. When the n-type and p-type layers are connected by a metallic wire, the electrons flow from the n-type layer to the p-type layer, creating an electrical current. The magnitude of the current generated in a solar cell is related to the amount of light falling on it. The anti reflective coating on a solar cells helps to increase the amount of light absorbed into the cell.
Conventional single crystal silicon based solar cells have efficiencies of around 22%. For polycrystalline silicon, efficiency will be around 15%. Other semiconducting materials can also be used for solar cells such as CdTe, CdS, CuInSe2.
Advantages of Solar Cell
- These cells are environmentally friendly
- Low operating costs
- Life time and durability is longer
- Solar cells are abundant and renewable
- Solar energy systems can enhance resilience during natural disasters.
Disadvantages of Solar Cell
- High installation cost
- Require significant space for installation
- Solar energy production can be affected by weather conditions such as rain, snow, dust, and pollution.
- Energy Storage Challenges
- Geographical limitations
Applications of Solar Cell
- Solar street lighting
- Residential solar power systems
- Satellites and space probes
- Portable solar chargers
- Solar-Powered Vehicles
For a hands-on approach to understanding the Solar cell experiment, visit our experiment page.
Summary
A solar cell (photovoltaic cell) is a semiconductor device that converts sunlight into electricity using the photovoltaic effect. It is built from silicon P–N junctions with metal contacts and coatings. Its efficiency depends on material, temperature, and light intensity. Solar cells are widely used in solar panels, calculators, satellites, and renewable energy systems.
MCQs on Solar Cell
-
A solar cell works on the principle of:
- a) Thermionic emission
- b) Photovoltaic effect
- c) Photoelectric effect
- d) Electromagnetic induction
Answer
b) Photovoltaic effect
-
The most commonly used material for solar cells is:
- a) Copper
- b) Germanium
- c) Silicon
- d) Aluminium
Answer
c) Silicon
-
Which parameter of a solar cell corresponds to maximum voltage without current flow?
- a) Short-circuit current (Isc)
- b) Open-circuit voltage (Voc)
- c) Fill factor
- d) Power conversion efficiency
Answer
b) Open-circuit voltage (Voc)
-
Solar cell efficiency depends on:
- a) Light intensity
- b) Semiconductor material
- c) Temperature
- d) All of the above
Answer
d) All of the above
-
The symbol of a solar cell is similar to a:
- a) Capacitor with arrows
- b) Diode with arrows indicating light
- c) Resistor with arrows
- d) Battery with arrows
Answer
b) Diode with arrows indicating light