One of the biggest questions that people ask about Solar energy that people ask is, “How does solar energy work?”
Well, in this article, we’re going to explain this in great depth. We’ll explain How Solar energy actually works.
Down below, we’ve explained the working of Solar cells, its physics, chemistry and some of the technical stuff regarding these. So, read carefully if you want to learn this seemingly complex thing once in for all.
It All Begins From Within The Sun
The solar rays that hit our solar panel contain countless little particles in them. Every single one of these particles takes tens of thousands of years to make it’s way from the sun to your solar panel. Billions of these particles need to hit your solar panel at a time to create any amount of traceable current.
This whole story begins in the center of the sun with the creation of photos. This happens in a process called nuclear fusion. In nuclear fusion, two smaller atoms merge to form a larger atom, and they release a huge amount of energy in the process. This little particle is called photon which is the bases of all this solar energy phenomena.
The photos are created in the center of the sun. From there, they get absorbed and emitted by billions of atoms again and again until they finally reach the surface of the sun. This process takes around forty thousand years on average.
After reaching the sun’s surface, photos travel in all directions at a lightening speed. It only takes about 8 minutes and 20 seconds for a photon to travel from sun to earth. That is 92,955,807.3 miles in just 500 seconds.
Now let’s introduce another character in story, electron. This tiny particle has a negative energy as compared to a photon. When the photon has traveled from the sun to the planet, it get absorbed by a particle. In this particle, photos transfers it energy to the electron, which gets excited.
Electrons keep gathering energy by getting it from the photons. Once this energy crosses a fixed limit, it makes the electron leave its atom by breaking the atomic bond. One high frequency photon is enough to make one electron escape its atom.
This theory (that we’ve just briefly explained) is still being tested by the scientists. More efficient materials are being developed to generate more electrons with a low amount of photons. This area of science is still under study.
If the photon has low frequency, it can’t excite the electron enough to make it leave its atom. Additionally, a large sum of low frequency photons are still unable to perform the task of a single high frequency photon.
As we mentioned earlier, countless photons are emitted in all directions from the surface of the sun. Many of these reach out planet and initiate the emission of electrons from their atoms. These emitted electrons in motion are called electricity.
The Research That Led to The Discovery of Current
The concept of current was first introduced by a French physicist A.E Becquerel in 1939. He was only 19 years old when he observed that throwing light on an electrode submerged in a conducting solution creates electrical current.
At first, this concept or theory was called the Becquerel effect. It is now known as the photovoltaic effect. His research was further analyzed by Albert Einstein. In a paper published in 1905, Einstein described the relationship between the frequency of incoming light and the energy of emitting electrons.
This paper first received a fair bit of skepticism since it contradicted most of the then estimated understandings of light. Einstein, for the first time, introduced the concept of Quanta (particle nature of light). But light was known as a single wave at that time. Einstein’s research supported both the Wave and Particle nature of light. He mentioned that light is made of numerous photos, and it travels in the form of an oscillating wave.
In 1914, R.A Millikan, through his famous experiment, proved Einstein’s research right. This was the creating of quantum physics. This also lead to Einstein receiving the Nobel Prize in 1921.
Einstein new way of looking at things changed how physics worked. His theories lead to the photoelectric effect. The transfer of energy from a photon to an electron explains how light can initiate and sustain an electric current.
A Russian Physicist Aleksandr Stoletov created the first ever solar cell in 1888. But an American Russel Ohl was the first one to patented the first solar cell.
Inventors at Bell Laboratories presented the first even working example of a photovoltaic (PV) cell. These cells are still largely used today.
Let’s Dig Into The Solar Panel Now
Photovoltaic cells have improved a lot in terms of their efficiency since the days of Aleksandr Stoletov. But the same concepts and basics are still in use.
Millions of solar panels used in around the world these days work on the same basic principles. Nothing has changed since the introduction of solar panels and solar cells.
We’ve already learned how photons from the sunlight can produce electrons to create an electric current. But this basic concept isn’t enough to light up our home.
In addition to the electrons, Voltage (electrical potential difference) is also needed to make the electric current flow from one point to the other.
This is where semiconductors come in. Every solar panel is made up of several small cells, which have glass windows to let the light pass through. The glass window also keeps the wafers of semiconductors below it safe.
Each wafer has crystals of silicon used as semiconductors. In a semiconductor, two layers of silicon are doped (one intrinsic and one extrinsic) and are put against each other. The n-type layer acts as the donor, while the p-type layer accepts the electrons. Phosphorus and Boron are used in these two layers respectively to give them their unique properties. This type of semiconductor is called P-N junction semiconductor.
In addition to silicon, there are lots of other elements used in the solar cells as well. But silicon is undoubtedly the most popular and widely used due to its unique properties, durability and efficiency as compared to other elements. But there are lots of other elements that are used to make solar panels for specific purposes. Organic photovoltaics are one of such interesting applications.
Organic photovoltaic cells have a huge potential. That’s because they can be mass produced at only a fraction of the price as compared to the silicon based solar panels. These cells are made from carbon rich polymers that can be modified to react efficiently to different bands of light.
However the organic photovoltaic cells currently have many shortcomings and drawbacks. The cell life is shorter as compared to the silicon cells, and efficiency is less than half of the silicon cells. But more research and development in this field can lead to the desired results.
So, we can say that the organic photovoltaic cells are the future, but not yet. However, with technological advancements, we can certainly achieve our goal. There are lots of other semiconductor materials still in the development phase. Each one has it’s own pros and cons.
Back to our original topic. When the photons excite the electrons, they (the electrons) leave their atoms. Now, the potential between P and N type layers in the semiconductor makes the electrons travel until they reach an electrode. That’s the whole part a solar panel plays in creating the electrical current.
From The Solar Panels to Your Appliances
The circuit isn’t complete yet.
A single solar cell alone can’t produce a usable amount of electricity. For this reason, many solar cells are arranged in a wide array to make a solar panel. Many solar panels are arranged in an array to make a system that can power your home or any other desired thing.
Smaller cells are connected in series or parallel system to combine their total produced electricity. The current is then directed towards a junction box, which is a small yet vital part of the solar energy setup. These junction boxes are connected to the solar panels are keep them safe from to much heat, insects and other external threats.
All of the current made by the solar panel comes to the junction box, which then redirects the current into a single wire that’ll power up your appliances. The junction boxes have diodes. Diodes have maximum resistance in one direction, and minimum in the opposite direction. These are basically semiconductors containing P-N junctions to maintain the flow of electricity in one direction. They prevent the feedback of energy into your solar panels.
The DC current is then fed to a solar inverter, which converts the DC current into a useable form, AC current. This is the final form of electricity that we use in our everyday appliances.
The AC current, after leaving the solar inverter, travels through the copper wires to reach your home’s electrical circuits. At this stage, you can power up your appliances with this current.
For added security, you can add circuit breakers and fuses. These keep your appliances safe from overload of energy. This is how that photon created in the center of the sun thousands of years ago ends up in our devices, including the one you’re reading this article on.
Different Types of Solar Inverters
There are different types of solar inverters that need to be understood before we move forward.
First type of solar inverters are the stand alone inverters. They aren’t connected to a central power grid. They are connected with batteries to store any surplus electricity for later use. Batteries have intelligent mechanisms in place to keep a check on the total incoming and outgoing amount of current.
The second type of inverters are grid-tie inverters. These inverters work in conjunction with a power grid. They are made to keep your appliances safe during the periods of grid maintenance since electricity availability varies in such scenarios. This mechanism is called anti-islanding protection.
The third and final type of inverters are hybrid inverters. They combine the functionality of both the stand alone inverters and grid-tie inverters. They can manage your solar power setup, and can also work with the grid at the same time. They are really useful, buy aren’t cheap to acquire.
We’ve covered everything from the creation of photos in the sun to their discovery, and how the sunlight ends up in the from of AC current that we rely so much on in our daily lives. These were all the in-depth details that anyone can ready to understand the basics of light and how its works.
Some Main Points
- Photons are small particles created in center of the sun due to nuclear fusion.
- Photons take roughly 40,000 years to make their way out of the sun’s center. They finally reach its surface.
- Once they’re on the surface, they reach our planet in 8 minutes and 20 seconds, by travelling at a speed of 186,282 miles per second.
- The energy released by photos in the solar cell displace the electrons of silicon. Then the semiconductors direct these displaced electrons to make electric current.
- All of the solar cells in a solar panel plays their part in creating the current. All of this current then travels towards the junction box, which combines it to form DC current.
- In an array of solar panels, DC current from all the junction boxes is fed into one solar inverter, which converts all the DC current into AC current.
- The AC current is then fed into your home’s circuits with the help of copper wires.
These were some of the key takeaways of this article. This is the very basics of how solar energy works. You can learn a lot more by searching on the web. The solar energy field has lots of potential, but there are still researchers under way to find more efficient materials, and to reduce the cost of solar panels.