Rashtriya Newsflash

Ninghai, China – As discussions about “space photovoltaics” continue to ripple across the industry, several key technical attributes are repeatedly emphasized: lightweight design, high-power output, radiation resistance, and long-term reliability. These requirements naturally direct the focus to a core technology Risen Energy has long been developing and has already deployed at scale—the application of ultra-thin silicon wafers in Heterojunction (HJT) solar cells.

Today, in the technical white paper released by Risen Energy in December 2023— Risen Energy’s HJT Hyper-ion: A White Paper on Development and Industrial Application of Ultra-Thin Silicon Wafers —it can be found that many of the ideas now emerging in frontier were already embedded in the practical engineering logic documented there. From addressing cost-reduction needs in ground-mounted power plants to building technical capabilities for space-level photovoltaic application, wafer thinning has never been a single optimization step for the company. Instead, it represents a systematic engineering approach built upon the intrinsic strengths of HJT technology, continuously expanding the depth of Risen Energy’s technical capabilities. This comprehensive record from the mass production front may offer the industry a perspective that combines technical insights and practical support.

Risen Energy’s HJT Hyper-ion: A White Paper on Development and Industrial Application of Ultra-Thin Silicon Wafers

1. Why “Thin”? An Inevitable Choice Rooted in Structural Nature

In the white paper, Risen Energy clearly points out that in the cost structure of HJT solar cells, silicon wafers account for the largest proportion at 55%. Therefore, wafer thinning is the most direct and effective method for cost reduction. However, the rationale goes beyond economics. It is fundamentally tied to the nature of HJT technology itself.

Cost Composition of HJT Solar Cells

Unlike conventional cell technologies that rely on high-temperature processing, HJT’s entire low-temperature manufacturing process (<200°C) and its fully symmetrical cell structure allow the wafer to be processed in a much “gentler” manner, which significantly reduce risks such as wafer warping and breakage issues caused by high-temperature processes and asymmetric stress inherent in PERC and TOPCon technologies. In this sense, ultra-thin wafers are not merely compatible with HJT — they are an inherent advantage of HJT technology, and one of the key enablers for its broader future applications.

2. How can “Thin” Remain Reliable? Systematic Balance of Efficiency, Yield, and Mechanical Strength

Transitioning ultra-thin wafers from laboratory concept to mass production requires overcoming several critical challenges. Risen Energy has conducted a series of explorations and practices focusing on efficiency, production yield rate, and mechanical strength:

2.1 Efficiency Trade-offs

As wafers become thinner, light absorption decreases—does this reduce efficiency? The experiments results, consistent with findings in industry literature, reveal an interesting “seesaw” relationship: while short-circuit current (Jsc) decreases with wafer thinning, open-circuit voltage (Voc) increases. The fill factor (FF) remains relatively constant. Within a specific “plateau” phase, the overall cell efficiency decline is minimal and acceptable. The width of this plateau varies across different cell technologies. For Risen Energy, HJT Hyper-ion cells manufactured with 110 μm wafers have already achieved an average efficiency of 26.4%, with the best production batches exceeding 26.6%. These results demonstrate that, for HJT technology, proper wafer thinning does not compromise the upper limit of performance.

Relationship between Silicon Thickness and Short-Circuit Current, Open-Circuit Voltage, Fill Factor, and Cell Efficiency

2.2 Manufacturing Optimization

As wafer thickness significantly decreases, how can stable operation be maintained on high-speed production lines? This requires comprehensive adaptations across wafer cassette design, handling methods, and equipment tooling. Risen Energy redesigned the wafer cassette configuration, switching from horizontal insertion to vertical insertion, while optimizing all related automation and transfer processes across the line. The results show a stabilized yield rate consistently above 99.5% with a fragment rate below 0.25%, proving that manufacturing challenges posed by “wafer thinning” can be overcome through systematic process and equipment innovation.

2.3 Mechanical Strength Rediscovery

Is thiner always more fragile? This widely held assumption deserves reconsideration. Risen Energy’s comparative tests revealed that 150μm PERC and 130μm TOPCon cells fractured during bending test. However, when the thickness was reduced to below 100 μm, the cells instead exhibited excellent flexibility. As shown in Risen Energy’s white paper, a 90μm HJT cell remained intact even at the maximum deformation range of the testing equipment. HJT cells exhibit exceptional flexibility, creating new possibilities for lightweight modules and special environment applications.

Risen’s flexible Ultra-Thin HJT Solar Cells

3. From Ground to Space: Extending the Depth of “Thin”

Risen Energy’s current mass-produced HJT Hyper-ion products for ground-mounted power plants fully utilize 110μm silicon wafers, and solar cell thickness of approximately 95μm. At this thickness level, Risen Energy has achieved optimal balance in efficiency, yield and reliability with significant cost reduction. Yet this represents only one aspect of Risen Energy’s technical capability.

Notably, for space photovoltaic applications, where an extremely high power-to-weight ratios is required, solar cells typically need to be 70μm or even thinner. Thanks to years of accumulated expertise in HJT ultra-thin wafer technology, Risen Energy has developed the capability to produce cells below 70μm. This capability did not emerge overnight. It is built upon the company’s deep understanding of HJT characteristics, sustained R&D investment in thin-wafer processes and encapsulation technologies, as well as systematic experience in integrated development from wafers to cells to modules.

4. Making “Thin” Work Effectively? System Innovation from Cell to Module

Excellent ultra-thin cells must be safely and reliably encapsulated into modules. Conventional high-temperature soldering is no longer suitable for such thin cells. To address this challenge, Risen Energy pioneered the Hyper-link stress-free cell interconnection technology. Protected by over 50+ exclusive patents, this technology avoids soldering thermal stress, perfectly matching HJT’s low-temperature characteristics and ultra-thin cells’ physical properties.

This innovation is backed by rigorous reliability testing, far exceeding IEC standards: 5400Pa static load, 10,000 dynamic load cycles, 2000 hours of damp heat (DH2000), 400 thermal cycles (TC400), and other accelerated aging tests. Results confirmed that Hyper-ion modules using ultra-thin wafers and Hyper-link technology show power degradation performance degradation far below standard requirements. This ensures that the lightweight benefits of thinner wafers never come at the expense of reliability. The reliability framework validated under harsh terrestrial conditions also provides a solid technological foundation for future space photovoltaic applications.

Reliability Tests on HJT Hyper-ion Modules

5. Integrated R&D

Reflecting on this journey toward ultra-thin wafers, the core lies not only in individual technological breakthroughs but also in integrated innovation across wafers, cells, and modules. Wafer thinning, low-silver metallization, zero-busbar cells, and Hyper-link technologies interconnect like puzzle pieces under unified design, ultimately forming Hyper-ion products’ complete competitiveness. This integrated R&D model helps solve cross-process coupling challenges systematically, rather than optimizing isolated performance indicators.

Risen Energy believes the mindset and methods developed for such systemic challenges hold value beyond technologies themselves. As the industry faces new challenges such as space photovoltaics, where performance, reliability and cost must all reach extreme levels simultaneously, leadership in single aspects may not be sufficient to ensure final product success. Risen Energy’s accumulated insights and approaches may offer valuable perspectives for peers exploring ultra-thin technologies or other system-level technical challenges.

Every step toward the stars begins with solid ground. Risen Energy’s ultra-thin wafer journey began responding to industrial cost-reduction needs and succeeded through respect for technological essence and commitment to systematic innovation. By revisiting and sharing this white paper, Risen Energy hopes to present the company’s current stage of reflection and industrial practice, and to work together with partners across the industry to drive photovoltaic technology toward a future that is lighter, stronger, and more imaginative than ever before.

About Risen Energy

Risen Energy integrates photovoltaics, inverter, energy storage, power station development, and smart energy management. Through strategic investments across the entire energy value chain—from production, conversion, and storage to consumption, operation, and management—Risen Energy accelerates the fusion of solar and storage.

For more information, please contact:

Risen Energy Co., Ltd.

[email protected]

Media Contact
Company Name: Risen Energy CO. LTD.
Contact Person: Min Xiao
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Country: China
Website: https://en.risenenergy.com/