Japan develops cylindrical perovskite solar cells to boost durability and output

A research team at the University of Electro-Communications in Japan has developed a technology that seals perovskite photovoltaic cells inside cylindrical glass tubes, similar to fluorescent lamps. By enclosing the perovskite material within glass, degradation caused by rain and wind can be suppressed. The cylindrical shape also enables energy absorption from all directions, potentially increasing power generation.

The university is working to commercialize the technology by improving the durability of next-generation perovskite solar cells through this cylindrical design. Compared to flat panels, cylindrical cells are expected to generate more electricity. A public-private collaboration alliance is scheduled to be established in October to advance mass production technology, expand applications, and conduct performance evaluations, with the goal of product commercialization.

Background and Challenges

Perovskite solar cells are highly anticipated as next-generation photovoltaic devices due to their light weight, flexibility, and high power conversion efficiency. However, they are prone to reaction with moisture and oxygen, leading to degradation of the crystal structure. Current durability is estimated at around 10 years, compared to approximately 30 years for silicon solar cells. Extending the lifespan of perovskite cells remains a major technical challenge.

Key Advantages of the Cylindrical Design

Power Generation: Up to Twice That of Flat Panels

By switching from a flat to a cylindrical shape, the cells can utilize not only direct sunlight but also reflected light from all directions. Research to date has confirmed that total daily power generation can be increased by 1.5 to 2 times compared to flat panels. Professor Shinji Yokokawa stated: "By receiving light from various directions throughout the day—not just when the sun is high—we can effectively increase total daily power output."

Expanded Installation Options

Flat photovoltaic panels require careful consideration of the sun's angle of incidence, limiting installation sites to open spaces such as vacant land or building rooftops. Cylindrical cells offer advantages in locations where direct sunlight is limited, such as urban building walls and farmland, as well as during early morning and evening hours when the sun's angle is low.

Field Testing and Progress

The research team has applied this technology to perovskite materials and began a demonstration test in April at the tea research center of the Japan Institute of Agricultural Technology in Kikugawa City, Shizuoka Prefecture. The test measures power generation and evaluates the growth of tea plants. Previous trials have shown that the cylindrical cells allow sufficient light transmission for tea plant growth, are resistant to wind and rain, and remain upright even during typhoons. Additional demonstration tests are planned in Oshima Town, Tokyo.

Plans for Commercialization

As research into effectiveness and safety progresses, the university plans to establish a public-private collaboration alliance to promote the industrialization of its research成果. The alliance will leverage the technical capabilities and development expertise of private companies to address key challenges for practical application, including glass tube processing and sealing, wiring, and power control.

With participation from Japanese electrical equipment manufacturers and cable companies, the alliance will establish methods for performance evaluation, safety assessment, and maintenance management. Professor Yokokawa emphasized: "To move beyond the university research stage toward social implementation, it is essential to collaborate with industry to develop the necessary mechanisms and rules."

Market Outlook

The global market for perovskite solar cells is expected to grow rapidly. According to Fuji Keizai, a Tokyo-based research firm, the global market size is projected to reach 147.6 billion yen in 2025 and expand to 3.948 trillion yen by 2040. In China, gigawatt-hour (GWh)-scale mass production facilities have already begun operation, and large-scale production systems are advancing. Among Japanese companies, Sekisui Chemical and others are also progressing with mass production systems.

Government Support and Strategic Importance

The Japanese government is promoting the development of the industry. In November 2024, the Ministry of Economy, Trade and Industry (METI) released the "Next-Generation Photovoltaic Cell Strategy," which outlines a coordinated approach to mastering mass production technologies, establishing production systems, and creating demand. The goal is to achieve approximately 20 gigawatts of installed capacity by 2040. Japan accounts for about 30% of global iodine production, a key raw material, making the technology strategically important from an economic security perspective.

Beyond Conversion Efficiency

Competition has expanded beyond conversion efficiency to include mass production technology, durability, and application development. Looking ahead to large-scale deployment, the University of Tokyo and other institutions are collaborating with industry to research recycling technologies for materials such as iodine and lead. Professor Shuji Hayase of the University of Electro-Communications and others are also advancing the development of lead-free perovskite solar cells that use tin as a substitute.

As Chinese companies accelerate the establishment of large-scale production systems, Japan must maintain competitiveness not only in price and conversion efficiency but also by developing new power generation sites such as building walls and farmland, and by promoting industrialization through proprietary technologies including recycling and lead-free solutions.

By Momoko Imamura, Nikkei