#China #Solar Technology #Risen Energy #Ningbo #Ultra-Thin Wafers

Exploring the Path of Risen Energy in Ultra-Thin Silicon Wafer Production

Introduction

As the dialogue around "space photovoltaics" continues to evolve within the industry, several crucial technical attributes are increasingly highlighted. These include lightweight construction, high-performance, radiation resistance, and long-term reliability. At the core of Risen Energy’s advancements is an extensive focus on ultra-thin silicon wafers utilized in Heterojunction Technology (HJT) solar cells.

The Significance of Ultra-Thin Wafers

Risen Energy has meticulously documented its technological evolution in a white paper titled "HJT Hyper-ion," shedding light on the synergy between scholarly engineering knowledge and practical applications.

1. Why Go Thin?

The choice for thin wafers is intricately linked to the structural characteristics of the HJT technology.
Statistically, silicon wafers account for around 55% of the cost structure in HJT solar cells, making it evident that reducing wafer thickness is a direct method to lower costs. Yet, this choice transcends mere economics; it is fundamentally tied to the manufacturing process of HJT solar cells, which occur at low temperatures (<200°C). This leads to lower risks of damage, such as warping or breakage typically observed in technologies like PERC and TOPCon, which operate at higher temperatures.

2. Balancing Efficiency and Mechanical Strength

Through rigorous research and testing, Risen Energy has explored the critical interaction between efficiency and wafer thickness. Initial findings indicate a ‘hammer-throw’ relationship where the short-circuit current (Jsc) diminishes with reduced wafer thickness, while the open-circuit voltage (Voc) sees an increase. This reveals a minimal decline in overall efficiency within a specific plateau phase, reinforcing that careful thinning does not compromise performance standards.

Manufacturing Optimization

To make the production process efficient, Risen Energy transitioned from horizontal to vertical wafer cassette configurations, streamlining automation processes and achieving consistent yield rates above 99.5%, with fragmentation rates below 0.25%. Such results showcase systematic innovations that tackle the challenges of thinning.

Mechanical Properties

Tests demonstrated that while PERC cells measuring 150μm and TOPCon at 130μm were prone to breakage in bending tests, HJT cells with thicknesses under 100μm exhibited remarkable flexibility, paving the way for lightweight modules and specialized applications.

3. Advancing from Ground to Space

Currently, Risen's commercially produced HJT Hyper-ion products utilize 110μm wafers, striking a balance between efficiency, yield, and reliability with substantial cost reductions. Notably, for space applications demanding a high power-to-weight ratio, Risen Energy has developed the capability of producing wafers thinner than 70μm.

4. Ensuring Robust Performance

For these ultra-thin cells, traditional high-temperature soldering techniques are inadequate. Risen Energy pioneered the Hyper-link technology, which connects cells without inducing stress, thus maintaining the low-temperature characteristics of HJT.

5. Comprehensive Research and Development

Risen Energy’s journey to ultra-thin wafers is not just about individual technology advancements, but integrated innovations in wafer processing, silver-low metalization, busbar-free cells, and Hyper-link technology. Together, these components create a cohesive product ecosystem.

Conclusion

The commitment of Risen Energy to ultra-thin wafers began in response to industry demands for reduced costs, rooted in respect for the technology's core essence and a promise of systematic innovations. This reflection and sharing of their white paper aim to present their current developmental phase while fostering collaboration within the industry to advance solar technology towards a lighter, stronger, and more creative future.