What Factors Contribute to the Degradation of N-Type Topcon Solar Cells Over Time? 

A recent study has shed light on the degradation characteristics of n-type bifacial Tunnel Oxide Passivated Contact (TOPCon) solar cells, revealing intriguing findings that provide valuable insights into the long-term stability of this promising photovoltaic technology. In this blog post, we will explore what factors contribute to the degradation of N-Type Topcon solar cells over time.

Also read: What Are the Best Practices for the Maintenance and Care of N-Type Topcon Solar Cells?

Moisture Ingress

Moisture ingress is a primary factor affecting TOPCon solar cells’ long-term stability. Even small amounts of moisture can corrode the metal contacts and degrade the passivation layers, leading to increased recombination losses and reduced cell performance. Moisture can enter the cell through gaps in the encapsulation materials or diffusion through the back contact. Researchers are actively working on developing better encapsulation techniques and moisture-resistant materials to mitigate this issue.

Light-Induced Degradation

TOPCon solar cells are susceptible to light-induced degradation, commonly referred to as “light soaking.” When exposed to sunlight, certain defects in the cell’s materials can create additional recombination centers, reducing the cell’s efficiency. 

The extent of light-induced degradation varies depending on the cell’s materials and fabrication techniques. Efforts are being made to understand the underlying mechanisms and develop mitigation strategies, such as passivation layer modifications and improved material quality.

Temperature Effects

Temperature significantly impacts the performance and degradation of TOPCon solar cells. High operating temperatures accelerate degradation processes, including metal contact corrosion, passivation layer deterioration, and increased carrier recombination. 

Proper thermal management systems, such as effective cooling methods and module designs, are essential to minimize temperature-related degradation. Additionally, advancements in materials with enhanced thermal stability can further improve the long-term performance of TOPCon solar cells.

Electrochemical Degradation

The presence of ionic impurities, such as sodium or copper, in the cell’s materials can lead to electrochemical degradation. These impurities can migrate under the influence of an electric field, causing corrosion and structural damage to the cell. Effective material purification techniques and stringent quality control measures during manufacturing can help minimize the introduction of ionic impurities and mitigate electrochemical degradation.

Mechanical Stress and Fatigue

TOPCon solar cells are exposed to various mechanical stresses during their lifetime, including thermal cycling, wind loads, and vibration. These stress factors can lead to material fatigue, delamination, and cracks and ultimately degrade the performance of the cell. Researchers are exploring novel materials and designs to enhance the mechanical robustness of TOPCon solar cells and improve their resistance to these stress-induced degradation mechanisms.

UV Radiation

Ultraviolet (UV) radiation, particularly in the short-wavelength range, can have detrimental effects on the performance of TOPCon solar cells. Prolonged exposure to UV radiation can cause degradation of the cell’s materials, leading to increased recombination losses and reduced overall efficiency. To mitigate this issue, researchers are exploring UV-resistant materials and advanced encapsulation techniques to minimize the impact of UV radiation on the cell’s long-term stability.

Chemical Contamination

Chemical contamination, such as the presence of volatile organic compounds (VOCs) or corrosive gases in the surrounding environment, can lead to the degradation of TOPCon solar cells. These contaminants can react with the cell’s materials, causing corrosion, deterioration of passivation layers, and increased recombination losses. It is crucial to control the quality of the manufacturing environment and develop effective protection measures to prevent chemical contamination and maintain the cell’s long-term performance.

Carrier Lifetime Decay

The study also revealed that n-type bifacial TOPCon cells exhibit a faster carrier lifetime decay than p-type cells. The faster decay can be attributed to the influence of the tunnel oxide layer, which introduces additional defects that accelerate carrier recombination. Efforts are underway to optimize the fabrication process and passivation layer design to minimize carrier lifetime decay and improve cell stability.

Aging of Encapsulation Materials

The encapsulation materials used to protect TOPCon solar cells from environmental factors can undergo aging over time. This aging process can reduce their protective properties, allowing moisture, UV radiation, and other harmful elements to penetrate the cell. It is important to develop encapsulation materials with excellent long-term stability to ensure the prolonged protection and performance of TOPCon solar cells.

Manufacturing Variations

Manufacturing variations and inconsistencies can impact the degradation and performance of TOPCon solar cells. Factors such as variations in layer thickness, impurity levels, and material defects can affect the cell’s stability and efficiency. To reduce such issues, manufacturers continually improve quality control processes and optimize fabrication techniques to ensure consistent and reliable cell production.

Interface Reactions

The interfaces between different layers and materials in TOPCon solar cells can be susceptible to reactions that degrade the cell’s performance over time. For example, reactions between the metal contacts and the passivation layers can lead to increased contact resistance and reduced carrier collection. Researchers are investigating interface engineering strategies to enhance the stability and reliability of these critical interfaces, ensuring long-term performance.

Conclusion

While n-type TOPCon solar cells exhibit excellent efficiency and low recombination losses, they are not immune to degradation over time. Factors such as moisture ingress, light-induced degradation, temperature effects, electrochemical degradation, and mechanical stress contribute to the long-term degradation of TOPCon cells.

 By understanding these factors and addressing them through improved materials, fabrication techniques, and encapsulation methods, researchers and manufacturers can enhance the stability and durability of TOPCon solar cells, ensuring their long-term performance in renewable energy systems. Continued research and development in this field will pave the way for more efficient and reliable solar cell technologies in the future.