After the photovoltaic industry has entered a new stage of "grid parity", technological innovation has become a key watershed in enterprise competition. Especially in the context of the increasingly slow improvement of battery efficiency, whoever can take the lead in breaking through the theoretical limit and realizing a commercially feasible high-efficiency route is expected to dominate the future market pattern. Trina Solar's recent perovskite/crystalline silicon tandem cell efficiency of 31.1% set a new global record, signaling that Chinese companies are accelerating their ascent to the top of the PV technology pyramid. This achievement not only demonstrates Trina Solar's technological accumulation and industrialization vision on the next-generation PV route, but also sends a clear signal to the reshaping of the global PV industry pattern: the era of stacking has arrived.
Ⅰ Technical milestone: Behind the world record of "31.1% efficiency".
In March 2024, Trina Solar's State Key Laboratory of Photovoltaic Science and Technology announced that its self-developed 210mm large-area perovskite/crystalline silicon tandem solar cell has been certified by Fraunhofer ISE CalLab in Germany with a maximum photoelectric conversion efficiency of 31.1%, once again setting a new global perovskite/crystalline silicon tandem cell efficiency record. This result is the 32nd time that the laboratory has broken the world record for battery efficiency, and has become another important coordinate on its technology roadmap.
What's more significant is that this efficiency record is based on a large-area crystalline silicon bottom cell with a specification of 210×105 mm², which is fully connected to mainstream industrial production lines. This means that high efficiency is not only in the laboratory stage, but also enters the stage of mass production scale path verification. The R&D team successfully solved the following three key challenges:
- Uniform deposition of perovskite films over a large area: Achieves a high-density, defect-free coating on a suede silicon substrate to improve device consistency.
- Electrical-optical matching optimization of top and bottom cells: Solve the series efficiency bottleneck inside the stacked structure.
- Interface passivation and carrier recombination suppression: The overall open-circuit voltage and fill factor are improved by a new interface layer material.
These innovations ensure that the entire stacked structure not only performs well, but is also compatible with existing 210 large-format module standards, laying the foundation for mass production.
Figure: Trina Solar set a new global record with a perovskite-crystalline silicon tandem cell efficiency of 31.1%
Ⅱ Theory and Reality: Why is Perovskite Tandem the "Next Direction"?
Perovskite is a new photovoltaic material with the advantages of high absorption coefficient, long carrier diffusion distance and low-cost preparation. As the upper absorber of tandem cells, it can effectively use the high-energy segment of visible light, while the lower crystalline silicon complements the infrared part, which complements each other and greatly improves the spectral utilization.
Figure: Multi-dimensional comparison of monocrystalline silicon cells and perovskite/crystalline silicon tandem cells
Single-junction solar cells are constrained by the Shockley-Queisser limit, and the theoretical efficiency ceiling has reached the top, while the perovskite tandem has room for further improvement due to its "double-junction synergy" mechanism. Driven by both efficiency and cost, perovskite tandem is becoming a new battlefield for global mainstream enterprises.
Ⅲ Frontier of industrialization: from technological breakthrough to product landing
Compared with all-perovskite tandem cells that are still in the early stage, the perovskite/crystalline silicon heterogeneous tandem path has obvious first-mover advantages in industrialization due to its high compatibility with the existing crystalline silicon production lines due to its underlying structure. Trina Solar's 210mm standard size has opened up the process path of high-efficiency tandem cells to verify its full-process mass production process, indicating that the route has moved from "proof of concept" to "engineering verification".
In addition, the perovskite tandem structure also has the advantages of high light decay stability and low temperature preparation process, and can be widely used in the following fields:
- BIPV (Building Photovoltaic): high efficiency can alleviate the problem of insufficient power generation caused by limited area;
- Distributed rooftop PV: The thin and light structure adapts to various rooftop scenarios.
- Portable power generation and on-board photovoltaics: higher power density and lightweight.
In these high value-added scenarios, tandem batteries are expected to be the first to be commercialized and gradually expanded to large-scale power station applications.
Ⅳ Technology Race: Chinese companies are reshaping the global PV landscape
Perovskite tandem has become a technological frontier that mainstream enterprises in China, the United States and Europe are competing to invest in. According to public information, as of the beginning of 2024, leading companies including LONGi, Tongwei, Huawei Digital Power, First Solar, and Oxford PV have launched relevant layouts.
However, from the laboratory to industrialization, the pilot process is the biggest challenge. In the past, international companies such as Oxford PV once set efficiency records, but they have not been able to achieve stable mass production. Trina Solar's breakthrough in industrial-sized cell efficiency + mass production path this time marks that Chinese companies have changed from "catch-up" to "leader" in the tandem photovoltaic field.
National policies are also being supported. According to a plan released by China's National Energy Administration, the cumulative installed capacity of domestic photovoltaic power generation is expected to exceed 300 million kilowatts by 2025. The new round of new energy installed capacity peak will provide the most realistic stage for high-efficiency technology.
Ⅴ Follow-up challenges and opportunities: tandem PV towards the era of 100GW
Despite the exciting breakthroughs, the industrialization of tandem cells still faces the following bottlenecks:
1. Mass production consistency and yield control: Large-area perovskite films still need to be further optimized in the roll-to-roll process.
2. Encapsulation and stability improvement: Perovskite materials are easy to absorb moisture and decompose, so new encapsulation materials need to be used.
3. Cost control: The additional material and process complexity brought about by efficient construction needs to be gradually diluted through technology integration.
However, under the continuous optimization of technology, the maturity of the equipment supply chain and the resonance of policy guidance, it is expected that perovskite/crystalline silicon tandem technology will usher in a window period from "megawatt trial production" to "100 megawatt production line" in the next 3~5 years.
Ⅵ Conclusion: It is not a miracle that tears the ceiling, but the ability of the system
Trina Solar's 31.1% efficiency is not only a laboratory achievement, but also a concentrated demonstration of system capabilities, from material innovation, process development to mass production path verification, the whole process is synergistically promoted, so that high-efficiency technology is no longer a "castle in the air", but a new productivity that can be implemented and scaled.
As the world's next-generation mainstream photovoltaic technology path, the development process of tandem cells will largely determine the technological competition pattern of the photovoltaic market in the next five to ten years. Trina Solar's breakthrough this time is not only a "leader", but also a powerful definition of the direction of the industry.
