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IBC Solar Panel Explained + Strengths and vs. Other Techs

In the pursuit of high-efficiency solar energy, the IBC solar panel has emerged as a compelling solution, which has gained increasing traction over the past decade or two.

But what exactly is an IBC panel, and how does it stack up against other cutting-edge panels, such as PERC and shingled panels?

This in-depth guide will delve into this panel technology and provide you with some hints to determine whether they are a good fit for your project.

What Is the IBC Solar Panel?

IBC (Interdigitated Back Contact) solar cells were initially developed in the early 1980s (Kuruganti, 2024), offering many pros over conventional cells due to their unique structure.

Composition & Structure

The term IBC refers to the unique design of the metal contacts in solar panels. Although the IBC technique is predominantly adopted in conventional crystalline silicon (c-Si) panels, its application is not limited to just these types of panels.

At the core of IBC panels is their relocation of both positive and negative metal contacts to the back of the panel. This poses a significant contrast to conventional solar panels, where the front surface has a grid of metal contacts that can obstruct incoming sunlight and are less appealing.

More specifically, the structure of an IBC c-Si solar panel can be illustrated in the figure below.

Schematic Drawing of the Structure of an IBC Solar Cell
C. Hollemann, Haase F, M. Rienäcker, et al. Separating the two polarities of the POLO contacts of an 26.1%-efficient IBC solar cell. Scientific reports. 2020;10(1). doi:https://doi.org/10.1038/s41598-019-57310-0

This example shows that a p-type c-Si material is prepared as the light-absorbing layer where electron-hole pairs are generated. On top of it are a passivation layer and an anti-reflective layer which are integrated to minimize recombination and maximize photon absorption, respectively.

Below the p-type c-Si base, a thin layer of SiOx material, commonly referred to as a tunnel oxide, is added to improve the efficiency and performance during energy conversion.

For an IBC solar cell to relocate front contacts to the rear side, it requires interspersed or interdigitated regions of n+ and p+ emitters. An intrinsic separator is typically inserted between an n+ emitter and a p+ emitter to form a p-i-n diode structure to facilitate conversion. 

Metal contacts are placed below the emitters using laser ablation or wet chemical deposition. Between the emitters and contacts, many IBC solar panel manufacturers will also add passivation materials to further reduce recombination losses.

Since front contacts are moved to the rear side, their visibility isn’t an issue. Generally, larger metal materials will be used. 

As the placement and alignment of emitters and metal contacts is a rather intricate job, photolithography techniques are performed to ensure accuracy.

How an IBC Solar Panel Works

An IBC solar panel works by absorbing sunlight through its entire front side. 

The absorbed light generates electron-hole (e-h) pairs within the silicon material. These charges are then separated by the electric fields created at the p-n junctions located on the rear side of the cell in an interdigitated pattern.

The electrons move to the n-type regions, and the holes move to the p-type regions, where they are collected by corresponding back-side metal contacts. 

The collected charges are then transported through an external circuit, generating electricity.

IBC Solar Panels vs. Similar Panel Techs

Among several higher-efficiency solar panel technologies, PERC and shingled panels rank high in market share, while sharing some similarities in their design philosophy with IBC panels.

IBC vs. PERC Panels

In short, PERC solar modules employ a straightforward and cost-effective approach to achieve higher efficiency. They upgrade traditional c-Si panels by adding an additional passivation layer along with local back surface fields on the rear side of panels.

Actually, a similar design is utilized in IBC solar modules. 

As mentioned earlier, passivation materials are also incorporated into the rear side of IBC cells, below the emitters. This design, which operates on a similar principle to PERC panels, effectively reduces recombination losses, thereby enhancing overall efficiency.

However, the key contributor to IBC panels’ elevated efficiency is their relocation of front contacts to the rear side, which maximizes the area available for sunlight absorption. 

IBC Panels vs. Shingled Solar Panels

The primary similarity between IBC and shingled solar panels lies in their design objective: both aim to maximize the surface area exposed to sunlight.

However, shingled solar panels utilize a rather different approach.

In a shingled module, each cell is cut into strips and these strips are overlapped in a manner similar to roofing shingles. Through the edge-to-edge stacking of cell strips across the module, the visibility of front metal contacts is significantly reduced. In addition, as compared to flat panel surfaces, the stacking arrangement directly boosts total light-capturing surface, with the tilts between strip rows being so subtle that they barely impact the panel's smooth aesthetic.

When to Use IBC Solar Panels?

IBC solar panels are known for their high efficiency, with some leading products capable of surpassing the 25% efficiency benchmark. This makes them ideal for applications where maximum power output per square meter is crucial, such as residential rooftops with limited space, commercial buildings aiming to amplify energy production as well as industrial projects requiring high energy yields.

On the other hand, the design of IBC panels eliminates the need for front-side metal contacts,  resulting in a sleek, all-black appearance. This makes them especially well-suited for projects where visual appeal is crucial, but BIPV products are not the optimal choice.

Last but not least, thanks to their unique design, efficient IBC solar panels are also a good choice for projects located in high-temperature environments. 

By arranging all contacts to the rear side, series resistance and heat dissipation can be better optimized. And in conjunction with the use of anti-reflective and passivation materials, the overall temperature coefficient of IBC panels is lower than that of traditional c-Si products. This property makes them maintain an efficient, smooth performance even under hot weather.

Understanding the Cost of IBC Panels

Unlike PERC panels which can be made using existing manufacturing processes with moderate retrofits, the manufacturing of IBC panels is much more complex involving the use of advanced processes and materials.

However, their higher initial cost can be offset by their increased energy yield and long lifespan, often guaranteed for 25-30 years. Study indicates that over a 25-year period, premium IBC panels can produce up to 55% more energy than traditional panels of the same size.

Some nationwide and local solar incentives for high-efficiency solar techs can help to mitigate the pressure of using IBC panels. And as IBC technology matures and becomes more widespread, economies of scale may reduce costs over time.

Wrapping Up: The Advantages of IBC Panels

  • Higher Efficiency: The IBC panel design offers maximum effective surface area for absorption, leading to higher conversion rates. This high efficiency translates to more electricity production from the same surface area, making them particularly advantageous in space-constrained installations.
  • Improved Aesthetics: The absence of front metal contacts lends IBC panels a more aesthetically pleasing appearance, making them especially popular for residential rooftops and architectural applications where they can enhance the property's value.
  • Enhanced Durability & Longevity: This panel design can result in less mechanical and thermal stress along with shielding from many of the environmental factors that cause wear and tear. Consequently, IBC panels often come with a long warranty and a longer operational lifespan than traditional panels.
  • Lower Temperature Coefficient: Their lower coefficient makes them deliver a better performance in hot climate installations, another numerical merit beyond high efficiency.
  • Simplified Optimizations: Since all contacts are located at the back, the optical and electrical optimizations for the cell are decoupled, streamlining the optimization processes. The ‘all-back-side’ arrangement also facilitates efficient heat dissipation and simplifies the optimization process for panel arrays.

Looking Into the Future & Final Words

Active research is underway in the realm of IBC solar panels.

Recent studies have integrated semi-transparent perovskite solar cells with IBC silicon cells to enhance overall performance. 

This year, Maxeon Solar has made significant strides in reducing hotspot risks in their IBC products, with their Maxeon 7 IBC cells showing a 70% lower average temperature rise in partial shading compared to competitors. 

Researchers at the ISC Konstanz and the Delft University of Technology have developed a novel patterning technique for IBC solar cells, highlighting the potential for even higher efficiencies in IBC panels through innovative manufacturing processes.

Anyway, IBC technology represents a widely recognized, leading-edge architecture in solar cells, specifically adopted to minimize any potential obstructions to sunlight exposure on the semiconductor material.

The IBC solar panel market is promising.

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