How Do Solar Panels Work

How Do Solar Panels Work? Read This First!

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Solar photovoltaic (PV) modules use the free and abundantly available energy from the sun to convert that energy into electrical energy for use. With such a unique and helpful resource available, you may ask: how do solar panels work?

Photovoltaic cells are what are used in solar panels. These cells, and therefore the panels, work by absorbing the solar energy that’s provided when the sun shines down on them. The PV cells directly absorb the sunlight and convert this into electrical charges that may then be moved and converted within the modules. After gathering this solar energy and converting it into electrical energy, a solar panel is built to then further convert this electricity into a usable form that may be utilized to power various items within the home or other vicinities.

However, this is just a simple and quick answer to the overall principle of how solar panels work. Keep reading to learn more about the internal structure of solar panels and the magic-like process of how these panels transform the sun’s energy into electricity.

1.   Photovoltaic Basics

Photovoltaic modules, or solar panels, consist of solar PV cells connected in a series, with more of these in a series increasing the voltage level capabilities of one of these modules. PV cells themselves are made up of pure silicon and topped with pentavalent and trivalent impurities to make ‘n’ and ‘p’ layers. At the junction of these two layers, there is a barrier of voltage when these modules are actively being used. The energy found in the photons of sunlight transfer energy to the electrons needed for power, and these flow in a closed circuit as an electronic current.

The voltage across a single solar PV cell is generated due to the p-n junction mentioned above, and an electrical current flows when the energy from the sun strikes the electrons in the ‘n’region. To obtain higher voltages from solar power, multiple cells may be connected in series to form a solar module. Multiple modules in a series further increase the voltage, and this is called a solar array. Multiple arrays in parallel give an even higher current in the circuit. This means that you can increase the total power through PV generation by adding more modules in series or parallel according to your system’s limitations.

2.   From Silicon to Electricity Generation

Selective, refined silica sand is used to extract 99% pure silicon, which is then further processed to reach 99.9% purity. To create either a p-type or an n-type semiconductor, trivalent and pentavalent impurities are added (boron and phosphorous, respectively).

A p-type semiconductor is placed on top of the silicon base as a very thin layer to create a p-n junction. The metallic backside of the cell serves as an electron collector. To reduce the reflection of radiation, an anti-reflective coating is placed on the front of the cell. Above the cell is a mesh portion made of metal strips that have been given the proper thickness for optimal functioning.

3.   Solar Module Components

Because they are so delicate, solar cells themselves cannot survive environmental adversity (strong winds, humidity, dirt, etc.). Solar modules have numerous layers to protect these cells and make them durable to withstand all these conditions without losing output efficiency throughout its average lifespan (i.e., around 25 years).

Here are the solar module components in layered form:

  1. Reinforced Glass
  2. Solar PV Cell
  3. Ethylene-Vinyl Acetate (EVA) Sheet
  4. Back Sheet
  5. Diode Box
  6. Metallic Frame

a. Top Glass

The front glass layer protects the PV cells from hail, dust, rain, and other flying debris from the environment. This glass is typically high-grade, toughened glass that is 3.0 to 4.0 millimeters thick.

b. Solar Cell

Solar cells are joined in series to add the voltage level. Different capacity solar modules have different cells in a series.

  • 36-cell modules provide 22 volts
  • 60-cell modules provide 38 volts
  • 72-cell modules provide 48 volts
    • 144-cell modules provide 48 volts

The 144-cell module is a 72-cell module with two sets in parallel to increase its current capacity. This kind of array is referred to as a half-cut solar module.

c. Metallic Frame

The aluminum frame serves two essential purposes: it holds the solar module in place during installation and protects the perimeter. The color of the anodized aluminum used for these is blackish-silver.

d. Ethylene-Vinyl Acetate (EVA)

EVA is a polymer (plastic) that was invented especially for holding solar cells in place. It has a high degree of toughness and resistance to high humidity and extreme temperatures.

e. Back Sheet

The layer at the back of standard solar panels acts as a moisture barrier and final external shell to provide protection and insulation.

f. Junction Box (Bypass Diodes)

In the junction box are the bypass diodes, which are necessary to prevent reverse current. Current can only flow in one direction through diodes. Unfortunately, bypass diodes can eventually fail and may need to be replaced. You can buy bypass diodes from Amazon and replace them by yourself when needed.

g. MC4 Connectors

All solar panels employ MC4 (multi-contact 4mm) connectors, which are specialized plugs and sockets with weather resistance. The ones shown here are 4mm due to the size of the inside circular pin of the connector. Extra connectors can also be found online, which can come in handy when installing a solar PV generation system.

4.   Photovoltaic (PV) Cell-Based Energy Generation

The photovoltaic effect is the process through which solar energy is transformed into electrical energy and solar energy is directly converted into electrical energy through photovoltaic cells (PV cells). A PV cell receives energy from the sun in the form of light and knocks electrons into the circuit. The voltage across the p-n junction of this cell is equal to the potential barrier of junction, and this is known as photovoltage.

a. PV Cell Generation Theory

Silicon carries four electrons in its outer shell and requires four more for the rest of its shell to be complete. On a single chip, pentavalent and trivalent impurities are added to silicon to create n-type and p-type semiconductors, respectively. A surplus of free electrons will emerge when doping with materials like phosphorous, which have five electrons in their outermost shell (an impurity of pentavalent). Doping with boron causes the generation of an electron vacancy, also termed to as a “hole,” which is due to trivalent element addition taking place.

The p-n junction is the region where the ‘n’ and ‘p’ layers converge. At this intersection, holes from one side mix with electrons from the other to balance each other out. This barrier is identified as the voltage barrier.

Silicon’s electrons are ejected when sunlight hits a solar cell, creating these “holes.” When both layers are joined by a cable, electrons begin to move to balance the layers, and the movement of electrons is known as electric current.

5.   Solar Module

An individual solar cell produces about 0.65 volts. It is basically useless to try to use this level of voltage to power any electrical device. In order to enhance the voltage level and make it usable for running everyday appliances, we connect numerous PV cells in series.

As we know, PV cells connected in series have the same current rating as single cells. Solar modules, or solar panels, are the series of combined PV cells.

Related Questions

Q: Is a solar PV cell really made of sand?

A: Yes. The basic material for solar cells, silicon, is extracted from molten sand, but it is converted into its purest form by different methods.

Q: What is meant by “doping” silicon?

A: The intentional and controlled addition of impurities in silicon is called doping. This is done to enhance conduction properties of the semi-conductor material.

Q: Can solar PV modules withstand a hailstorm?

A: As the average lifespan of a PV module is more than 25 years, it should go without saying that the front glass layers of all solar PV modules are designed to withstand the worst kinds of hailstorms and other environmental condition. Additionally, the aluminum frame is designed to withstand strongest of wind gusts as well.

Q: Can you repair a solar module if its glass is broken?

A: Solar module glass cannot be repaired if it is broken because the tempered glass on the top of module is fused with the PV cell array, and any method to remove it will damage the cell and its grid.

Q: What is effect of partial shading on a solar module?

A: A shadow caused by any object that blocks the sun exposure on a solar module, even partially, is problematic for the module as well as the whole array of modules connected to it in the series. As cells are connected in series in single module, any shadows or shading will cause a blockage in the passage of current, and this will act as a heating resistor that can destroy the entire module.

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