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| Monocrystalline Solar Panels |
How Produse Solar Energy from Photovoltaic Cell or Solar Panels?
You can even teach your friends about it In fact. I guarantee that even the electrician that installs solar panels in your area would not have the knowledge you will get in this article. In this article we will give the information in a casual and light hearted fashion on how exactly a photovoltaic cell works. If we look at other machines that generate electricity. We will note that they have an alternator inside them when it revolves it produces electricity.In a generator the engine rotates the alternator, Hydro turbine, water moves the alternator through turbine blades In Wind turbine, it is the wind that rotates the alternator and produces electricity. Similarly, if you have seen the dynamo in a bike than you would know that it has to be again rotated to produce electricity it. If you have seen Piezoelectric crystals that are present in Quartz watches those crystals have to be vibrated for generating electricity.
The photovoltaic cell is a strange device that does not have any revolving or moving component but still it produces solar energy (electricity) So long as it gets light. How let’s explain why this happens Similar to photovoltaic cell (PV panels) is a battery. The battery too doesn’t have moving components but still it generates solar energy electricity due to Chemical reaction.
The difference of PV panel (Photovoltaic cell) and battery is that battery charge finishes, But Photovoltaic cell (PV panels) keeps producing solar energy as longs as it is exposed to light.
Photovoltaic Cell and Diode
So let’s go deeper into exploring Photovoltaic cell (PV panel). To understand PV panel we have to understand an electronic component called Diode. Diode is a very basic electronic component. That has numerous applications if we look at the construction of a diode. We will see it a very simple device. Two separate materials are joined to form it One material is called P- Type material and other one is called N- Type material. |
| Diode |
For making P-Type material, we take molten Silicon We dope it with very small quantity of Boron, Aluminum or Gallium. What it does is that when Silicon solidifies than impurity creates gaps in the structure/ lattice that can be filled up by electrons.
So this is a bit about P-Type material N-type material. For N-type material we use different impurities for doping. The substances uses for doping are Antimony, Arsenic or Phosphorous. The ratio of impurities cab be said to be as salt in flour. What it does that when Silicon solidifies, than it creates restricted space for electrons? One can say that P-type material and N-type materials are opposites of each other meaning P-type has more room for electrons, while N-type has less room for electrons.
When we join P-type and N-type materials at the interface, something interesting happens. N-type material that has little room for electrons and P-type that has more room. When they are joined than at the interface some electrons from the N-type material, jump into the P-type material. You can see this in the diagram.
P-type and N-type material
Because of electrons jumping into P-type material from N-type, there is a deficiency of electrons Now in N-type material. Therefore near the interface in the N-type material There is a layer of negative charged particles (in P-type) On the other hand the electrons that jump into the P-type material. They do get space, but because now P-type materials has extra electrons. This makes a layer of negatively charged particles in P-type material near interface.We have a layer in N-type material that is positively charged. In P-type that is negatively charged both these layers combined are called Depletion layer or Depletion region. Now if any further electrons try to jump from N-type material to P-type material than the depletion layer becomes a barrier between them. This depletion layer acts as a wall. Now if electrons want to go across than they need energy.
We apply voltage across this P-N diode than the electrons can get the energy they need to cross the depletion region however. This voltage needs to be higher than 0.7 Volts. This was just how a diode works meaning. If we apply a voltage across the diode of more than 0.7 Volts than it allows the electricity to flow otherwise it does not. Now that we have understood diode, it’s not difficult to understand solar panels because just like diode.
Solar Panels
Solar panels are also a PN junction if you look in the diagram, you can see the P-N junction in a solar panel. The top layer is N-type material while bottom layer which is normally hidden away is P-type material. Now when a ray of sun hits the panel than it passes through the thin layer of N-type material and reaches the depletion region in P-type material. This ray hits the electrons that jumped from the N-type material it knocks them back into N-type material.As a result, a hole is created in P-type material and N-type material gains an electron that is looking to go back in the P-type material. If you take a wire and connect one end of it to N-type material and other end to P-type material than a passage is made for the electron. That has been knocked back to return to the P-type material at a time. It is not one electron but immeasurable amount of electrons would complete this journey on the incidence of light. We can say that the wire that has been connected between P and N type material gets current flowing through.
It you may have noticed that on a solar panel there is a metal mesh on the top. This mesh is there to collect those electrons that will have been knocked out of P-type depletion region into N-type material on the incidence of solar rays we connect the wire mesh to wire.
If we connect and electrical appliance to the wire than the current will pass through the wire. The appliance would run if the voltage required by the appliance is what the solar panel is producing any solar panels.
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| Polycrystalline Solar panels |
Types of Photovoltaic cell or Solar Panels
1- Monocrystalline2- Polycrystalline
3- Thin film
They only have the capacity to convert only 33% of light into electricity. We call this limit Quizzer-Shockley limit. There is a huge amount of solar energy that only converts into heat.
Mono Crystalline
When it lands into the panel only 33% of the solar energy in light knocks out electrons into N-type material and it is only this energy that converts into electricity. The difference between mono and polycrystalline silicon is that for making mono, when silicon is in the molten state and is solidifying than during solidification. We can control the cooling so that it crystallizes from only one direction.Polycrystalline
When silicon crystallizes in this fashion, than it does not have cracks in its structure. In polycrystalline molten silicon will allowed to cool without control Silicon starts solidifying from many sides. That multi-directional Silicon solidification meets than cracks will created in structure.The polycrystalline is not very efficient because these grain boundaries add resistance to electron flow. But a poly panel is cheaper than mono panel. Because the process of crystallization in mono is very expensive and requires a lot of time.
Thin Film panel
The P-type material and N-type materials will made just like a paint or ink. In a Thin-Film panel you paint the P-type material on a surface. and then you paint a layer of N-type material over that this process is very cheap. Therefore Thin-film panels are also cheap but not very efficient.I hope that you would have liked this article and learned a lot from my article 'how to produce solar energy from photovoltaic cell or solar panels'. You would spread this knowledge among your friends. Thanks for your attention.
