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The growing global demand for energy and the growing problem of climate change are driving us to seek more efficient and sustainable energy transition solutions. The solar industry has paved the way for higher-power solar panels with different solar cell technologies that seek to reduce power loss, increase efficiency and reduce the cost of producing photovoltaic (PV) modules.
One of the most innovative ways to demonstrate higher efficiency using crystalline silicon (monocrystalline silicon) cells is IBC solar cell technology. This post will explain the materials and structure of IBC (Interdigitated back contact) solar cells and explain how the technology works.
1. What is an IBC solar cell
The main component of most IBC solar cells is a monocrystalline silicon wafer that acts as an absorber layer for n-type wafers, but p-type wafers are also used. Monocrystalline silicon (monocrystalline monocrystalline silicon) is the most common choice due to its higher efficiency, but polycrystalline silicon (polymonocrystalline silicon) can also be used.
An antireflection and passivation layer is disposed on one side of the monocrystalline silicon wafer and disposed on a thin layer of silicon oxide by a thermal oxidation process. Materials such as silicon nitride (SiNx) or boron nitride (BNx) are also suitable.
In order for IBC solar cells to reposition the front contacts on the back of the battery, they require a layer of interspersed or finger-forked emitters, called a diffusion layer. To create it, layers of n-type wafers diffuse by masking, masking ion implantation, or laser doping doped boron, producing p-type numbers, while the n-type layers remain intact.
Metal contacts are also placed by laser ablation or wet chemical deposition, using conventional metals such as silver, nickel or copper as contacts for IBC solar cells. This is one of the most popular methods for manufacturing IBC solar cells, but different methods are available, but different materials are required to make the diffusion layer.
2. Structure of IBC solar cell
Considering the formation of diffusion layers, manufacturing IBC solar cells can be quite complex, but understanding their structure is relatively straightforward. The main layer of IBC solar cell is n-type or p-type monocrystalline silicon wafers that act as an absorbent layer.
This layer is fabricated by doping a single crystal silicon layer with boron or phosphorus to produce a p-type or n-type doped wafer. Then, an antireflective passivation coating, usually made of silicon oxide, is placed on one or both sides of the solar cell.
The main structural design modification of IBC solar cell is the inclusion of diffusion layers, which are characterized by crossed n-type and p-type layers that allow the installation of backside metal contacts.
Finally, each metal contact of the IBC solar cell is placed on the back of the battery, leaving the front of the battery completely free of shadow material. This also allows contacts to be installed over a wider area, reducing the battery's series resistance.
3. How does IBC solar cell work
IBC solar cell produces solar energy under the photovoltaic effect, just like Al-BSF solar cells. And in the distributrd pv system, the load is still connected between the cathode and anode of the IBC solar panel, and photons are converted into electricity, generating solar energy to power the load. As with conventional solar cells, photons hit the absorption layer of the IBC solar cell, exciting electrons and creating electron holes (e-h).
Since IBC solar panels do not obscure the front metal contacts of the cells, these solar cells have a higher photon impact conversion area. The e-h pairs formed in front of the IBC solar cell are then collected by a p-type finger layer on the back. The collected electronic contact flows to the load, generates electricity, and then returns to the IBC solar cell, ending a specific e-h.
4. Comparison of IBC solar cells and conventional batteries
After learning more about IBC solar cell, it is important to compare them with the well-known traditional Al-BSF technology. In this section, we will consider different aspects to compare these two options. One structural improvement of IBC solar cell from the design of traditional Al-BSF cells is the removal of the front metal contacts of the battery.
This provides two advantages to IBC solar cell technology: reducing shading by positioning metal contacts on the back of the battery, and increasing power density by allowing solar cells with no gaps in the middle to be installed on IBC solar panels. Thanks to improvements in IBC solar cells, IBC technology achieves a recording efficiency of 26.7%, which is 1.3% higher than conventional technology.
IBC solar cell technology doesn't stop there, as researchers expect IBC solar cell to be 29.1% efficient. IBC solar cell technology increases the temperature coefficient of traditional options. Therefore, IBC solar panels can provide better performance in hot weather installations.
Although IBC solar cells are expensive to produce and the manufacturing process is complex, the cost of the technology has been reduced. With higher efficiency and slightly higher prices, IBC solar cell technology is a good choice for home energy storage and commercial applications, which could lead to IBC technology controlling about 35% of the market share by 2025.
While Al-BSF and IBC solar panels can be used in residential and industrial applications, IBC solar cell technology dominates CPV applications. This is caused by IBC solar panels with lower series resistance, higher volume life, and lower surface compounding. Making it ideal for these applications with increased solar energy concentration offers several interesting advantages.
5. Benefits of IBC solar cell
IBC high efficiency solar panels have a number of advantages that make them stand out from traditional Al-BSF technology and others. In this section, we will summarize the advantages of IBC solar cell technology.
● Losses are reduced by coloring
IBC solar cell recombination places metal contacts on the front side of the battery, eliminating shadows caused by busbars. By doing so, IBC solar cell increases the efficient absorption of photons, thereby reducing power loss.
● Reduce series resistance
IBC solar cells have become a key factor in CPV applications by placing larger metal contacts on the back of the battery, reducing the series resistance of the battery, thereby reducing the series resistance of traditional Al-BSF cells.
● Increase power output per square meter
With the improvement of the efficiency of IBC solar cells, IBC solar panels can be manufactured without space between the cells. This further increases the power output per square meter of a single module. This makes IBC solar cell technology more attractive for space-constrained applications. And solar bettery price will get more benefits on this point.
● Independent optical and electrical optimization
Because IBC solar cells reposition metal contacts on the back, the optical and electrical optimizations of the cells are decoupled, making each optimization completely independent of the other, making it easier for researchers to improve one or the other individually.
6. Conclusion
Solar cells play an important role in solving energy challenges. Photovoltaic cells convert solar radiation into electricity through the photovoltaic effect, and are a device that directly converts renewable solar energy into electrical energy. However, traditional battery technology still has some limitations in terms of efficiency and performance.
In order to overcome these limitations, IBC photovoltaic cells came into being. IBC cells adopt a special electrode structure, which greatly improves photoelectric conversion efficiency. With the continuous advancement of photovoltaic technology, different types of photovoltaic cells emerge one after another, and IBC solar cells as one of the emerging technologies with high efficiency, has attracted widespread attention.
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