Solar Energy: What is it & How it works?

Did you know that the sun is the first source of energy on earth? The solar energy coming from the sun is later converted into renewable & non-renewable forms.

When the sun’s energy is captured through photosynthesis; it leads to the formation of Non-renewable energy sources like fossil fuels.

On the other hand, renewable energy sources are produced by the direct influence of the sun; uneven heating of the atmosphere causes wind energy.

This post is all about solar energy and it’s working. 

After going through it, you will get to know about:

1. What solar energy is?
2. Photovoltaic effect
3. The complete working of solar power systems.
4. Benefits of adopting solar.

Before we begin to understand solar energy, you should be well aware of what energy is & its various forms.

Energy is:

“the ability of a system to do work.“

And, the work is done when the transfer of energy from one form to another takes place.

For example, when we run the chemical energy stored in our body converts into heat energy. And, this heat results in increased temperature of our body.

This is how energy transfer takes place. 

There are various forms of energy like mechanical, electrical, radiant, wind, solar energy, etc.

In this post, our main focus is on solar energy, what it is & how it works.

Let’s dive right in!

What is Solar Energy?

Earth receives a huge amount of energy directly from the sun in the form of heat.

Have you ever wondered how to collect heat and transfer it into usable forms?

Let’s have a basic understanding of it.

Heat Transfer

There are three ways to transfer heat from one system to another :

1. Conduction
2. Convection
3. Radiation     

Let’s understand each of them. 

Conduction

It refers to the transfer of heat from one system to another by direct contact.

For example, when we fry an egg over a pan, the pan becomes hot due to the heat that transfers from the flame to the body of the pan.

Convection

It refers to the transfer of heat through the movement of liquid and gases in a system as the molecules circulate.

Boiling water is a perfect example of convection. 

When heat is given to the water, it first transfers to the water molecules present at the bottom-most layer of the vessel & makes it hot.  

Then this layer of hot water molecules rises up & the next layer of cold water molecules sinks. This process continues until the water boils.

This process is known as convection.

Radiation

It refers to the transfer of heat through space in the form of waves.

The heat that we receive from the sun is radiant heat i.e, it is in the form of waves and photons.

Trillions of photons reach the earth’s atmosphere every second.

According to Wikipedia, the Earth receives 174 petawatts (PW) of incoming solar radiation at the topmost layer of our atmosphere.

Using specific methods, we can use solar energy by converting it into various other usable forms of energy such as electricity, heat, and fossil fuels.

One such method is the use of solar panels.

Solar panels are devices that are used to absorb the sun’s rays and convert them into direct currents.

Before we discuss how solar energy works, you should know what the photovoltaic effect is. 

Photovoltaic Effect

As we know sunlight is in the form of photons. 

We use solar cells made of semiconductors (usually made of Silicon) to transfer photons of sunlight into usable forms.

Semiconductors are materials having conductivity between insulators (e.g. plastic) & conductors (e.g. iron).

The conductivity of semiconductors increases with the increase in temperature. These semiconductors are used to make solar cells.

When a photon hits a solar cell, one of these three things can happen:

1. The photon can pass straight through the cell (low energy photon).
2. It can be reflected by the surface of the solar cell.
3. It can be absorbed by the surface of the Solar cell.

When the photon is absorbed by the silicon to create electricity. This is known as Photovoltaic Effect.

Suggested Readings: History of Solar Power

Diagrammatic Representation of Photovoltaic Effect

When a photon is absorbed, its energy is given to the electron in the crystal lattice. The crystal lattice refers to the symmetrical 3-d arrangement of atoms inside a crystal.

When the electron leaves the p-type silicon, it leaves its place empty, creating a hole.

An electron from the neighboring atom moves into the hole leaving another hole behind. In this way, the holes are spread all around the lattice.

As this happens, the flow of electricity begins in the circuit that the solar cell is connected to.

Ideally, a photon with an energy equal to that of the bandgap hits the solar cell.

And this photon excites an electron from the valence band to the conduction band.

Different materials have different bandgap energies as shown in the below table:

S.No	Semiconductor	Eg(eV)
1	Ge (Germanium)	0.67
2	InSb (Indium Antimonide)	0.18
3	Si (Silicon)	1.12
4	GaP (Gallium Phosphide)	2.25
5	ZnSe (Zinc Selenide)	2.7
6	Diamond	6.0
7	GaAs (Gallium Arsenide)	1.42

Today, Silicon is used in most solar cells because of its chemical properties.

Also, the photons have energies greater than the bandgap of silicon. The difference between the photon energy and silicon band gap is converted into heat.

It is all about Photovoltaic Effect. Now, Let’s see how solar panels work?

How does the Solar Power System work?

A solar power system is a complete structural arrangement of how solar energy works.

Below is the step-by-step guide on the working of a complete solar power system:

1: First, the solar panels convert energy from the sun into DC (direct current).

2: Next, the inverter converts the DC output of solar panels into AC (alternating current) power suitable for our homes and small businesses.

3: After the current is converted into AC, Switchboard is used to distribute electricity between electrical sources which are protected by fuses or switch gears.

4: Now, the digital meter measures your electricity production and consumption. In other words, these meters display the real-time data of both incoming and outgoing electricity.

5: Finally, we can use a power grid to deliver electricity from producer to consumer.

The power grid is nothing other than an interconnected network of transmission lines.

This is how the solar power system works. Last but not the least, have a look at the benefits of adopting solar power. 

Benefits of Adopting Solar

Solar power is a completely free source of energy. We don’t have to pay for it.

So we can say that, as long as there is sunshine, solar energy can be deployed anywhere.

Studies proved that it is one of the cheapest sources of energy.

Thus, we can also say that it is the easiest energy source available.

For remote areas where it is quite hard to deliver electricity, solar power seems to be the easiest option.

Even, according to Wikipedia,

“Solar energy is expected to become the world’s largest source of electricity by 2050”.

Furthermore, You can also have a look at the below infographic that clearly depicts the benefits associated with the use of solar energy.

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• Top 10 Largest Solar Parks in the World
• Indirect Forms for Solar Energy

Conclusion

In this post, I have explained solar energy, heat transfer, the photovoltaic effect, and working of the solar power systems.

I hope after reading this post, you have a better understanding of solar energy and the benefits of adopting solar.

Still, if you have any queries or suggestions, do not hesitate to leave a comment in the comment section below this post.

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