How Does the Photovoltaic Effect Convert Light into Electricity?
Many of us have been using solar panels in our homes for quite some time and are saving a huge amount of money on our electricity bills. But how does a solar panel work, and how does it create electricity which powers our homes? Well, here we have explained the working of a solar panel that works on the principle of the photovoltaic effect. The photovoltaic effect, or in short, PV effect, is the process that enables a solar panel to generate voltage or electric current.
The solar panels you see in solar power plants are made by photovoltaic cells and exposed to the sunlight. It is the effect that makes the photoelectric effect of solar panels are useful and allows them to generate electricity in the first place. The photovoltaic effect in solar cells was first discovered in 1839 by Edmond Becquerel when he experimented with wet cells.
Explain Photovoltaic Effect
The photoelectric effect of solar panels happens due to the presence of two different types of semiconductors. These semiconductors are p-type and n-type. These two are joined together to form a p-n junction. By making these two junctions come together, an electric field is formed in the junction region, and electrons start to move to the positive side, and holes that are present in the cell start to move to the negative side, which is the n-side. The electric field causes the charged particles to move in one direction and positively charged particles to move in the other direction.
Now you might not know, but the light is coming from the sun, and all the other forms of light are composed of photons, which are also known as the small bundles of electromagnetic radiation energy. These photons, when they hit the surface of the photovoltaic cell, get absorbed, and their energy is transferred to the cells present in the cells. Precisely the energy of the photons goes to the electrons which are present in the material. As a result, the electrons get excited, and they start jumping to the higher energy state, which is known as the conduction band.
Once the electrons are jumping to the conduction band, they leave behind holes in the valence band. This movement of the electron creates energy and makes two charge carriers along with an electron-hole pair. All in all, the motion of the electrons when they move in the excited state causes energy formation which also leads to a photoelectric effect in solar panels, which then converts into electricity by the solar cell. This was the principle of the photovoltaic effect on solar panels and solar cells.
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(Solar panel in solar power plant.)
Soiling Effect on PV Modules
When there is soiling, you are going to face a power loss, that's for sure. The Pv modules' power output depends on their amount of irradiance, which catches the solar cells. Several factors come into play that define the optimal output of the PV module. However, the PV module environment is one of the leading parameters that define the optimal output of the solar cell. A soling effect is the loss of a generation of electricity due to snow, dirt, dust, and other particles that stuck at the PV module's surface, making it hard for the protons of the sunlight to hit the surface and transfer their energy. Even dust that forms on the solar cell with time leads to the soling effect, and it depletes the overall energy generation of the panel.
Conclusion
That's how a solar cell works, and that's how with the use of the photovoltaic effect, it can generate clean electricity for us to use. The future of energy generation depends on how we use solar panels and how much efficiency we can make them. As our sun will last for more than 1 billion years from now on and being able to create electricity from it is surely a blessing that we need to take advantage of.
FAQs on Photovoltaic Effect: Definition, Working & Applications
1. What is the photovoltaic effect in simple terms?
The photovoltaic effect is a physical and chemical phenomenon that generates a voltage and electric current in a material upon exposure to light. It is the fundamental principle behind how solar cells work. In essence, when light particles (photons) strike a semiconductor material, they transfer their energy to electrons, allowing them to break free and create a flow of electricity.
2. How is the photovoltaic effect different from the photoelectric effect?
While related, these two effects are distinct. The key difference lies in their application and mechanism:
- Photoelectric Effect: This is the emission of electrons from a material's surface (usually a metal) when light shines on it. The focus is on the emission of electrons into a vacuum or gas.
- Photovoltaic Effect: This occurs within a semiconductor structure, typically a p-n junction. The light creates electron-hole pairs, and an internal electric field separates them, generating a voltage within the material itself without emitting the electrons from the surface. The photovoltaic effect is essentially a specialized case of the photoelectric effect harnessed within a semiconductor device.
3. Why is a p-n junction crucial for the working of a solar cell?
A p-n junction is essential because it creates a permanent, built-in electric field, known as the depletion region. When light generates electron-hole pairs, this internal field plays a critical role by separating them before they can recombine. It pushes the free electrons to the n-side and the holes to the p-side, establishing a potential difference (voltage) across the junction. Without this built-in field, the generated electrons and holes would quickly recombine, producing heat or light instead of a usable electric current.
4. What are some common real-world examples that use the photovoltaic effect?
The most prominent example of the photovoltaic effect is the solar panel, used for generating electricity for homes, power plants, and satellites. Other common applications include:
- Solar-powered calculators and watches.
- Garden lights and streetlights.
- Solar-powered battery chargers for mobile devices.
- Photodiodes and phototransistors used in light-sensing circuits.
5. How does increasing temperature impact the performance of a photovoltaic cell?
Increasing temperature generally decreases the efficiency of a photovoltaic (solar) cell. As the temperature rises, the semiconductor's bandgap narrows slightly, which leads to a minor increase in current. However, it causes a much more significant decrease in the open-circuit voltage. The net result is a reduction in the overall power output (Power = Voltage × Current). Therefore, solar panels perform optimally in bright but cool conditions.
6. What would happen to the electron-hole pairs generated by sunlight in a piece of silicon that does not have a p-n junction?
In a simple piece of silicon without a p-n junction, sunlight would still generate electron-hole pairs. However, without the internal electric field of a depletion region to separate them, these pairs would wander randomly. Within a very short time (nanoseconds to microseconds), the free electron would recombine with a hole, releasing its extra energy as heat or a low-energy photon. No sustained voltage or current would be produced, and the light energy would be lost rather than converted into useful electrical energy.
