Recently, the First Space Photovoltaic Materials and Technology Conference was held in Ningbo, Zhejiang. Under the theme “Driving Technological Transformation Through Space Missions and Reshaping the Industrial Landscape Through Independent Innovation,” the conference brought together aerospace research institutes, universities, research institutions, leading companies across the photovoltaic industry value chain, and equipment manufacturers to discuss technologies related to space solar cells, encapsulation materials, and specialized equipment. Dr. Li Guo, Senior R&D Engineer at the Photovoltaic Technology Center of Tongwei Co., Ltd., was invited to attend the conference and deliver a keynote speech.

At the conference

Addressing Extreme Space Environments with Tongwei’s Technological Solutions

During the conference, Dr. Li Guo delivered a keynote speech titled “Space Photovoltaics: Advantages of p-Type Heterojunction Cell Technology and Tongwei’s Technological Capabilities.” Starting from the vast opportunities emerging in the space sector driven by commercial aerospace, he systematically analyzed three major challenges facing space photovoltaics: significantly stronger ultraviolet irradiation under the AM0 spectrum than on Earth, extreme thermal cycling between −170°C and +150°C, and damage to the silicon crystal lattice caused by high-energy particle radiation.

Based on semiconductor physics and reliability analysis, Dr. Li proposed a preferred technological combination for addressing the space environment: gallium-doped p-type silicon wafers + heterojunction (HJT) structure + ultra-thin substrates + copper interconnection.

Minority-carrier migration rates in p-type substrates are approximately three times those in n-type substrates, while their radiation damage coefficients are lower. Highly resistive, gallium-doped p-type silicon offers superior radiation resistance. The conventional-polarity HJT structure provides the shortest minority-carrier collection path, enabling efficient collection of short-wavelength photogenerated carriers and current even after electron irradiation reduces minority-carrier lifetime. Ultra-thin substrates reduce the effective transport distance required for minority carriers, mitigating efficiency losses caused by reduced minority-carrier lifetime after irradiation. Copper interconnection uses pure-metal grid lines to minimize the introduction of organic materials. Combined with an ultra-dense, ultra-fine grid pattern, this approach balances lightweight design with radiation-resistant reliability.

The “p-HJT + copper electroplating” combination is one of the most viable technological solutions for current space-based crystalline silicon photovoltaic applications. Tongwei’s cells based on this pathway have achieved an AM0 conversion efficiency exceeding 21.5%.

Dr. Li Guo, Senior R&D Engineer at the Photovoltaic Technology Center of Tongwei Co., Ltd., delivers a keynote speech

From Earth to Space, Tongwei Has Built Up Key Technological Capabilities

As the first company in the global photovoltaic industry to enter the Fortune Global 500, Tongwei has developed capabilities that can be adapted to space applications across several key technologies, supported by its vertically integrated industrial chain and global innovation and R&D centers.

Tongwei began HJT research and development in 2018, and its module power records have subsequently been broken 12 times. The company has achieved the fabrication of ultra-thin HJT cells with a thickness of 55 μm, with related research featured on the cover of *Nature*. Its ultra-thin wafer capabilities provide a foundation for lightweight photovoltaic modules designed for space applications.

Tongwei plans to bring its copper interconnection technology, also known as copper electroplating, into gigawatt-scale mass production in 2026–2027. The technology features grid-line widths of less than 20 μm and spacing of less than 0.4 mm.

In addition, Tongwei has established the industry's first fully automated 5 MW pilot line for perovskite-crystalline silicon tandem cells, achieving an efficiency of 34.94% for small-area cells. This provides room for further technological development toward next-generation space solar cells with higher power density.

Extending the Boundaries Through Innovation, Enabling Photovoltaics to Change the World

From ground-mounted power plants to low Earth orbit, Tongwei is steadily extending its accumulated expertise in high-efficiency crystalline silicon technologies to space applications.

For space photovoltaics to progress from technical feasibility to commercial viability, the industry must work together to address several engineering challenges, including aerospace-grade reliability validation, automated mass manufacturing, and testing standards specifically designed for space applications.

Looking ahead, Tongwei will continue to advance p-HJT, copper interconnection, and tandem technologies. By collaborating with aerospace organizations, research institutes, and equipment manufacturers, the company aims to advance the commercialization of domestically developed materials and processes for space photovoltaics. Through green electricity solutions offering lower costs and higher reliability, Tongwei seeks to support emerging applications such as commercial aerospace and space-based computing, extending the vision of “Photovoltaics Changing the World” from Earth to the vastness of space.