Everything you Need to Know About a Multi Junction Solar Cell

Increasing problems of climate change, global warming, ozone layer depletion, and more, are the result of greenhouse gases that fossil fuels emit. Hence, going solar is the need of the hour. 

If you are planning to install a solar system to meet your electricity requirements, congrats, you are taking the best step to make your surroundings worth living. 

After the invention of solar panels that consist of a multi junction solar cell, it is possible to convert most sunlight into electricity.

Curious to learn more about this latest invention? Continue reading to understand all the details about multijunction solar cells.

What are Multijunction Solar Cells?

As the name suggests, a multi junction solar cell is made with different layers of semiconductors. These layers play the role of absorbing sunlight and converting it into electricity.

Now you may think about the need to have multiple layers of semiconductors.

Well, sunrays have different wavelengths, and this is the basic reason why you see seven colours in a rainbow. When the rays of different wavelengths hit a multi junction solar cell, they get absorbed. 

This way, solar panels with multiple junctions have higher efficiency than traditional ones. 

How are Multijunction Solar Cells Made?

Now that you know that a multi junction solar cell has different layers for light absorption, it’s time to understand how these layers are made.

A traditional single-layer solar cell is made with silicon semiconductors. However, for a multi junction solar cell, materials like indium gallium, germanium, and gallium indium phosphide are used as semiconductors. 

All these layers are stacked atop one another to increase the solar panel’s efficiency.

Working of a Multi Junction Solar Cell 

To understand the operation of a multi-layer solar cell, you must know how exactly sunlight converts to electricity. For this, let’s look at the working of single-junction solar cells first. 

Traditional solar cells have two layers:

• N-type: Consisting of high electron concentration
• P-type: Consisting of relatively lower electron concentration

As the sun’s rays hit the n-type layer, electrons move from one layer to another, creating an electric current. This flow of current is electricity. 

In a multi junction solar cell, the stacking of three layers of semiconductors creates two junctions. Thus, when the sunlight hits the semiconductor layer, the electrons move to all the layers. With the presence of two junctions, more power is produced, resulting in high efficiency.

This way, the multi-junction solar cells are capable of generating more power. The following points summarise the photovoltaic effect used by solar panels for power production in simple terms:

• Sunlight gets trapped in the solar cells and loosens the electrons present in the semiconducting layer.
• Loosened electrons travel through the multiple junctions of semiconductor layers, resulting in the creation of electric charge.
• The conducting wires connected to the panels transfer the generated electricity to the solar inverter that converts DC electricity into AC electricity.

What is the Highest Efficiency of Multi-Junction Solar Cells?

A multi junction solar cell has more than one p-n junction for the absorption of electric current. This helps maximise electricity generation. 

So, what is the maximum amount of power a solar panel with these cells can produce?

During lab research, developers and inventors have found the efficiency of multi-junction cells to be around 43%. This figure is far more than the maximum efficiency of a single junction cell, which is around 25%. 

What are the Limitations of multijunction solar cells?

All the points discussed above prove that multi-junction solar cells are the best solution for eco-friendly power generation. However, it comes with certain limitations, such as:

• Due to the complicated production process and multiple material requirements, the price is higher.
• Presently, they are not available in the commercial market. 
• They need highly concentrated sunlight to generate maximum electricity. 

Comparison Between Single Junction and multijunction solar cells 

Now, let’s briefly understand the differences between multiple and single-junction solar cells. For this, we will consider three broad factors: material, efficiency, and price.

Factors	Single junction solar cells	Multijunction solar cells
Material	It mostly uses silicon as the semiconductor material.	It consists of different semiconductor layers made with three separate materials, namely:Gallium indium phosphide (GaInP)Indium gallium arsenide (InGaAs)Germanium (Ge)
Efficiency	Most efficient solar panels are capable of converting 22% to 25% of sunlight into electricity.	During the research and development phase, it has been proven that these cells have a nearly 43% efficiency rate.
Price	With the passing of time and the perfection of the manufacturing process, prices are becoming affordable.	These cells are yet not open for commercial purposes.

Is it Possible to Install Multi-junction Solar cells?

The multi-junction solar cells come with promising technology. Additionally, they have the potential to improve the performance of solar panels. However, they are not yet commercially available for solar panel installation because they are still being tested and investigated.

Many leading solar panel manufacturers provide high-efficiency modules that successfully convert sunlight to electricity, so you may benefit from clean and readily available solar power if you’re interested in installing solar systems for personal or commercial power requirements.

Conclusion 

Innovations in solar cell composition, construction, and design are at the forefront of ongoing advancements. 

This results in increased solar panel efficiency. Additionally, it is expected to improve further with the intriguing technology of multi-junction solar cells. 

FAQs

1. Can I use solar trackers for multi-junction solar cells?

The use of solar trackers is recommended for solar panels used for commercial and industrial purposes. 

Besides, the multi junction cells are yet not launched. So, whether or not trackers will be required for them is a discussion for another day. 

2. How does a multi junction solar cell generate higher electricity as compared to traditional panels?

This solar cell consists of multiple layers of semiconductors. It creates multiple junctions for power absorption. As the sun’s rays hit the semiconductors, different junctions absorb photons from different wavelengths of light, resulting in higher power generation.

3. What is the highest efficiency of multi-junction solar cells theoretically?

Theoretically, a multi junction solar cell offers about 87% efficiency. According to more practical tests in the labs, the efficiency is found to be approximately 43%.