How Solar Panels Work And Generate Electricity

how solar panels work

How Solar Panels Work And Generate Electricity

A solar system converts sunlight into electricity. Solar panels are like the engines of a solar system. Photovoltaic cells play a fundamental role in electricity generation.

The power generated by these cells leads to the solar system’s output. Here we have covered how solar panels work, from the basic to the advanced level concept.

What is Solar Energy?

Solar power is energy from the sun that can be used for generating electricity, producing heat, or creating chemical reactions. Let us illustrate the importance of solar power with an example.

The Thar desert receives 6 to 7 kWh/m² every day. It has an area of 238,254 km². So the total solar energy incident on Thar desert every day is between 1429.524 TWh to 1667.778 TWh.

Compare this to India’s projected peak power demand. As per the 20th Electric Power Survey (EPS) Demand projections, India’s power demand will hit 2473.8 TWh in 2031-32.

Therefore, if we can harness all the solar energy incident on the Thar desert, India will be able to meet 57% to 67% of its power requirements from solar electricity even when power demand is at its peak.

How a Solar Cell Works: Doping and Photovoltaic Effect

The chemistry of photons and electrons makes a solar cell work. 

Silicon is most commonly used to make a solar cell. The silicon consists of 2 layers:

Top Layer: It is an n-type layer with a mixture of silicon and phosphorous. N stands for negative.

Bottom Layer: It is the p-type layer with a mixture of silicon and boron. P stands for positive.

But why do we add phosphorous and boron to silicon? To answer this question, you need to understand the science of doping.

The Science of Doping

Adding impurities like phosphorous or boron to silicon is called doping. Doping is necessary to allow electricity to flow through the silicon. 

A silicon atom has 14 electrons, with 4 in its outermost shell. A silicon atom needs 8 electrons in its outer shell for maximum stability. That’s why a silicon atom shares electrons with 4 other silicon atoms to achieve stability.

The Science of Doping

Image: The Engineering Mindset

Phosphorous has 5 electrons in its outermost shell. 4 of these electrons are shared with silicon atoms and one extra electron is left. This makes the phosphorous-doped junction negative.

Boron has 3 electrons in its outermost shell. All these 3 electrons are shared with silicon atoms, thus leaving an extra space for electrons called holes. It makes the boron-doped junction positive.

Thus the n-type layer has an excess of electrons while the p-type layer has a shortage of electrons. The section where the 2 layers meet is called the p-n junction. Around the p-n junction is a layer called a depletion region or a space-charge region.

The Depletion Region

Image: The Engineering Mindset

In the depletion region, some electrons from the n-type layer move towards the p-type layer and some holes from the p-type layer move towards the n-type layer. The holes and the electrons quickly recombine with each other.

Thus a part of the p-type region is depleted of the holes imparted by boron impurity and becomes negatively charged. A part of the n-type region is depleted of the electrons imparted by the phosphorous dopant and becomes positively charged.

It leads to an electric field in the depletion region, ensuring that no further movement of electrons can take place from the n-type silicon to the p-type silicon.

electric field

Image: The Engineering Mindset

Why is this important? Because, if electrons in the n-type silicon are attracted to holes in the p-type silicon, they must pass through the solar circuit, and not through the p-n junction. Only then will the home solar panel system generate electricity.

Photovoltaic Effect

Now let’s discuss the sunlight falling on the panels and how it helps to generate electricity.

Sunlight is made of particles called photons. These photons contain energy which can knock off electrons in the outer shell of the silicon. How much energy must the photon have? It needs an energy of 1.1 electronvolt.

When sunlight falls on the solar cells, it passes the thin n-type layer and directly reaches the p-n junction. It knocks off electrons which are attracted to the holes in the p-type silicon. 

The electron can’t go through the p-n junction due to the pre-existing electric field. So it goes towards the n-side and flows through the external electric circuit. This is how solar electricity is generated.

The generation of electricity using sunlight is called the photovoltaic effect.

How a Solar System Powers Your House

We have already explained how a solar cell generates electricity. Now we will explain what happens after the electricity is produced.

First, the electricity is sent to an inverter. The solar electricity is in Direct Current (DC) form. But this can’t be used to power a home. Home appliances work on Alternating Current (AC). The inverter performs the function of converting DC into AC.

Do you want to install a solar system? You can get the best quotations for solar installation on your website. We are the 1st company in India to offer free quotations for solar installations.

Where is the Electricity Stored?

There are 3 different systems for storing the electricity.

On Grid Solar System

In an on grid solar system, DISCOM’s power grid stores the power. It helps you save on your electricity bills as you only pay for the difference between your electricity consumption and the power you export to the grid.

We have written in detail on on grid solar system. You can read our blog to learn more about how this system works.

Off Grid Solar System

In this system, a battery stores the power. The advantage is that you can use solar electricity in case of a power outage.

Hybrid System

A hybrid system uses a battery as well as the DISCOM’s grid to store the electricity. Once the battery is fully charged, the solar system will send the rest of the solar electricity to the DISCOM’s grid for storage.

Therefore, depending on the type of solar system you have installed at your home, you draw solar electricity either from the DISCOM’s grid or a battery to power your house.

Structure of a Solar Panel

Here are the major components of a solar panel:

  • Solar Cells

Solar cells convert sunlight into electricity. An anti-reflective coating is put on top of the cells to minimise the reflection of sunlight and maximise solar power absorption. Electricity flows through thin strips called fingers which stay connected perpendicular to larger strips called busbars.

inside a photovoltaic cell
  • Encapsulant

An encapsulant holds photovoltaic cells in position. It protects them from damage and moisture.

They have excellent adhesive properties that helps in bonding well with the front glass as well as the back sheet or back glass. Ethyl Vinyl Acetate (EVA) is most commonly used for encapsulation.

Here are some properties to look for in a solar panel about the encapsulant:

  1. Potential Induced Degradation (PID)-resistant
  2. Low Moisture Vapour Transmission Rate (MVTR)

Image: RenewSys India

  • Front Sheet

A glass sheet covers the front side of the panel. It is made of tempered glass and has an anti-reflective (AR) coating. It protects the cells from damage, pollution, and moisture. 

Here’s how the thickness of the glass varies:

Type of Panel

Thickness

Glass-to-Glass

2 mm

Glass-to-Backsheet

3.2 mm

  • Aluminium Frame

An aluminium frame holds the entire solar panel together. It has to be strong enough to resist wind and weather-related damage. 

The frame accounts for a significant proportion of the panel’s weight. It is usually made of silver.

  • Back Sheet

It is placed at the rear of the panel. It can be white, black or transparent in colour. 

A back sheet protects the panel from moisture, and damage and acts as insulation. If the back sheet is transparent, the solar cells can absorb sunlight from the rear as well. For this feature, the panel is called bifacial.

Apart from glass back sheets, these are the different types of plastic composite back sheets that can be used: 

  1. Two-side fluoropolymer layered back sheet
  2. Single-side fluoropolymer layered back sheet 
  3. Fluoropolymer-free back sheets
  • Junction Box

The junction box is fixed to the rear of the panel. Cables are used to interconnect the panels via the junction box.

A bypass diode is a critical component of the junction box. It ensures that electricity flows in only one direction and does not flow back to the solar panel.

Here are the usual features of a junction box:

  1. IP67/ IP68 rated
  2. Split junction box with individual bypass diode

MC4 compatibleYou have learnt about the structure of a solar panel. But how are they set up? A mounting structure holds the panels and points them towards the sun. You can read my blog on mounting structures for solar panels to know more about them.

To get the maximum output out of your solar system, your system must be installed correctly. How will you ensure that your vendor has the skills to install it correctly? 

Das Energie Private Limited has solved this problem. We have created a platform where vendors can put up quotations so that customers like you get the best value for money while installing the solar system.

To make the best decisions regarding your solar system, it is important to understand how solar panels work. A solar system can drastically reduce your electricity bills. It is also a clean form of energy. It prevents CO2 emissions which are typical of thermal power plants.

India is playing a major role in the global solar landscape. Some of the world’s largest solar power plants, including the largest, are in India. You can read our blog on the largest solar power plants in India to learn more about them.

Frequently Asked Questions:

A solar panel is most efficient when sunlight falls perpendicularly on the solar panels.

The main factor that influences the generation of solar electricity is the incidence of sunlight on solar panels. Even in cloudy or rainy conditions, if sunlight falls on the solar panels, the solar system will generate electricity.

No, it is not compulsory to install a battery for storing solar electricity. You can also store the electricity in the DISCOM’s grid.

2 Comments

  • Ranjit Chatterjee

    July 7, 2024 - 6:52 am

    Have read many blogs on how solar panel works but this blog seems different. Clarified clearly.

  • Ajay Mishra

    July 7, 2024 - 5:20 pm

    Will a solar panel work if a shadow partially covers it?

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