Japan Bets on Ultralight Perovskite Solar Panels at Expo 2025 Osaka

A 250 Meter Solar Roof Shows Japan's Ambition

More than 250 ultrathin perovskite solar panels cover the curved roof of Yumeshima Transportation Terminal 1 at Expo 2025 Osaka, turning a bus terminal into a demonstration of Japan's next solar industry. The installation stretches 250 meters, and the electricity it generates powers the terminal's lighting.

Developed by Sekisui Solar Film Co., Ltd., the panels weigh about one tenth as much as conventional solar panels. Their flexibility allows them to follow the roof's curves, opening up places for electricity generation where heavier, rigid panels would be difficult to install. The terminal is the world's largest installation of its kind.

Japan's ambitions extend far beyond the Expo grounds. The Ministry of Economy, Trade and Industry (METI) has committed $1.5 billion to support the development and commercialization of ultrathin, flexible perovskite panels. Production plans, domestic supplies of iodine and national energy targets connect the technology to a broader effort to reduce dependence on imported solar equipment and revive Japanese manufacturing.

As of July 22, 2025, the Expo is also testing smaller applications: solar panels on workers' vests, curved panels on street poles and transparent cells incorporated into building facades. Together, these projects explore whether solar generation can become part of everyday infrastructure and objects.

World Expos have long presented technological breakthroughs, from the Crystal Palace in London in 1851 to the debut of the escalator in Paris in 1900. Osaka's perovskite demonstrations continue that tradition, while putting a practical question at the center of the display: how much more space can generate electricity when solar panels become lighter and flexible?

What Makes Perovskite Different?

Perovskite solar cells take their name from a family of materials with a particular crystal structure. Japanese researchers first discovered their photovoltaic properties in 2009. Photovoltaic means that a material can turn light into electricity.

Conventional solar panels use silicon and are generally rigid. Perovskite cells can be made as flexible films, with panels sometimes just one millimeter thick. That changes where solar equipment can go: curved surfaces, roofs that cannot carry much extra weight, clothing and building materials all become possible locations.

Perovskite cells are lighter and can be cheaper to produce than silicon panels. They can absorb a broader range of light, including visible light and near infrared light, which lies just beyond what human eyes can see. They can also generate electricity under cloudy skies or indoor lighting.

Laboratory versions have achieved power conversion efficiencies exceeding 26%, rivaling the best silicon panels. Efficiency describes how much incoming light energy becomes electrical energy. A higher percentage means a cell produces more electricity from the same amount of light.

Panels being tested in practical applications are achieving around 15% to 21% efficiency, with rapid improvements expected as the technology develops. Those figures describe a different stage of development from the strongest laboratory results. Japan's task is to turn promising cell performance into products that can be made in large quantities and used reliably outside.

Why the Bus Terminal Matters

Yumeshima Transportation Terminal 1 gives the technology a visible job: supplying electricity for lighting in public infrastructure. Its long, curved roof also demonstrates an architectural use that suits flexible solar films.

Sekisui's panels could bring solar generation to older buildings, disaster prevention centers and schools where traditional equipment would be too heavy or too rigid. Their low weight creates options for using existing structures instead of relying entirely on new solar farms.

The terminal therefore serves two purposes. It supplies power at the Expo and tests how a large installation of flexible panels works as part of a public facility. For Japan, the project is also a statement of its intention to lead the next generation of solar technology.

Workers Test Solar Vests in Osaka's Heat

Expo staff members are testing utility vests fitted with perovskite solar panels developed by Toyoda Gosei, a Toyota Group company, Enecoat Technologies and textile manufacturer Seiren. The panels supply power to neck fans intended to help workers stay cool during Osaka's summer heat.

Each panel weighs less than four grams. The project is described as a world first initiative to integrate perovskite solar cells into wearable technology, taking the material away from rooftops and placing it on something a person can carry through the working day.

The development team is collecting daily performance data under different weather conditions. Those measurements will help guide the next generation of products by showing how the panels perform during actual use, with changing sunlight and weather.

Toyoda Gosei plans to launch commercial smartwear by 2027. The Expo trials provide a step between an experimental product and clothing designed for wider use. In this application, the benefit is concrete: a lightweight source of electricity attached to a vest can power a device used by the wearer.

Street Poles and Facades Become Power Sources

Smart street poles at the Expo use curved perovskite panels to support lighting, digital signage and wireless charging for benches. These installations explore how generation can be placed close to the equipment that needs electricity.

Panasonic has developed artistic facades using transparent perovskite solar cells sandwiched between glass layers. The approach turns a building's exterior into an electricity generator while retaining its visual appeal.

The street poles, glass facades and solar vests show different sides of the same idea. Perovskite films can fit into shapes and surfaces that are less suitable for conventional panels. A roof remains a useful place to collect sunlight, but walls, public furniture and wearable equipment can also become part of the generating system.

Data from these installations will inform later products. Their variety matters because a panel used on a building exterior faces different practical demands from one attached to clothing or wrapped around a street pole.

Domestic Iodine Supports an Energy Strategy

Japan's interest in perovskite is tied to the materials used to make its solar cells. Iodine, a main raw material for the Japanese technology, is sourced domestically. Silicon panels depend heavily on imported polysilicon, much of it from China.

More than 60% of the world's solar panels are produced in China. By developing a technology supported by homegrown resources, Japan hopes to reduce its dependence on foreign suppliers and protect itself from disruptions in global supply chains and geopolitical risks.

Japan's mountainous terrain also limits the expansion of traditional solar farms. Flexible panels offer another route: adding generation to cities, existing buildings and infrastructure rather than depending only on large areas of suitable land.

The industrial goal is to regain leadership in renewable energy while reviving manufacturing. The energy goal is to make solar power a larger part of Japan's electricity supply, with a target of 30% by 2040. Perovskite technology connects those aims by creating a potential domestic industry whose products can reach places conventional panels struggle to serve.

Investment and Production Plans Take Shape

METI's $1.5 billion commitment is intended to support both development and commercialization. Commercialization means taking a technology from research and demonstrations into products that customers can buy and use.

Sekisui Chemical is receiving government subsidies to scale up production. Its plans call for 100,000 kilowatts of production capacity by 2027 and one million kilowatts by 2030. The later figure is ten times the earlier target, showing the scale of the planned expansion.

Japan's broader ambition is for electricity generated by perovskite cells to match the output of 20 nuclear power plants by 2040. Reaching that goal would require the technology to spread far beyond demonstration projects into public facilities and urban infrastructure.

Sekisui Chemical aims for widespread adoption of its solar films in those settings. Production growth and installation growth must move together: factories need to make the panels, while buildings and infrastructure need suitable ways to incorporate them.

Durability, Lead and Price Need Answers

Moisture, heat and ultraviolet light can damage perovskite materials, causing them to degrade and lose efficiency within a few years. Durability is one of the most pressing challenges before the cells can rival or replace silicon panels on a large scale.

Researchers are working on encapsulation, which means protecting the cells with coatings and other barriers. Protective layers and additives are intended to shield the sensitive material from the environment and keep it generating electricity for longer.

Sekisui's latest panels have achieved a lifespan of about 10 years. The company is targeting 20 years to match conventional solar panels. That target would double the stated lifespan of its current technology, a change that matters for building owners deciding how long an installation can serve them.

Many perovskite formulations also contain lead. Although the amount is small and robust encapsulation can minimize environmental risks, researchers are investigating alternatives without lead and better recycling methods to address health and ecological concerns.

Price presents another challenge. Perovskite cells can be cheaper to manufacture, but initial commercial products are expected to cost more than silicon panels. Mass production and improvements in manufacturing processes are expected to bring prices down as the industry grows.

Flexible panels may still offer an advantage in locations where standard equipment is impractical. Easier installation and access to otherwise unusable surfaces could help offset a higher initial price, particularly in urban settings. For buyers, the decision will depend on the cost of the installation, the electricity it produces and how long it lasts.

Japan Joins a Global Technology Race

The International Solar Alliance (ISA) is hosting events at Expo 2025 to encourage partnerships between countries including India and Japan. The collaborations aim to build resilient solar supply chains, accelerate investment in next generation technologies and promote innovation in clean energy led by young people.

Other developers are combining perovskite with silicon rather than concentrating only on flexible films. These tandem panels place a perovskite layer on top of a silicon cell and are already boosting efficiency by up to 20%.

Oxford PV in Europe is commercializing these hybrid panels. Japanese firms are focusing on pure perovskite technology and solutions integrated into buildings. The approaches address different opportunities: improving the electricity output of a silicon panel, or allowing solar generation on surfaces that conventional panels cannot easily use.

The shared commercial challenge is to achieve mass production, competitive costs and reliability over many years. International cooperation at the Expo takes place alongside that competition to bring the technology into wider use.

Solar Fits Into Japan's Wider Energy Targets

Japan's 7th Strategic Energy Plan places the perovskite push within a broader change in energy policy. The government's goals include a 73% reduction in greenhouse gas emissions by 2040 and carbon neutrality by 2050.

Renewable sources are targeted to provide 40% to 50% of the electricity mix, with perovskite solar cells expected to play a crucial role. The solar target of 30% by 2040 makes expanding generation on buildings and infrastructure an important part of the strategy.

Tokyo's new solar mandate, starting in April 2025, requires panels on new homes. It could add 1 to 1.5 gigawatts of solar capacity annually, linking the growth of residential solar generation to construction.

The Expo projects explore additional settings beyond conventional residential rooftops. A flexible film on an older public building, transparent cells in a facade and panels on a transportation terminal each create another possible place to generate electricity.

From Demonstrations to Everyday Use

The Expo's wearable vests, smart poles and building installations are practical experiments as well as displays. Their performance data will help manufacturers decide how to improve the next generation of products and which applications are ready for wider use.

The next milestones include Toyoda Gosei's planned smartwear launch in 2027 and Sekisui Chemical's production targets for 2027 and 2030. Those dates move the story from what visitors can see in Osaka toward what customers may eventually use elsewhere.

Perovskite's thinness, low weight and flexibility create potential uses in clothing, smartphones, windows and vehicles. Those possibilities depend on researchers and manufacturers improving durability and scaling up production.

Japan's bet is that electricity generation can become more adaptable and closer to the people using it. If the technology succeeds, cities could generate more of their own power and become more resilient to climate change. For now, the Expo brings the opportunity and the remaining engineering work into the same public view.

Key Points

• More than 250 perovskite panels cover the 250 meter curved roof of an Expo bus terminal and power its lighting.
• The panels weigh about one tenth as much as conventional panels, allowing installation on surfaces unsuitable for heavier equipment.
• Expo trials include solar vests powering neck fans, smart street poles and transparent cells in building facades.
• Japan is backing development with a $1.5 billion METI commitment and domestic supplies of iodine.
• Sekisui Chemical plans production capacity of 100,000 kilowatts by 2027 and one million kilowatts by 2030.
• Durability, lead management and initial prices remain major challenges; Sekisui is targeting a lifespan of 20 years.
• Japan aims for solar power to supply 30% of its electricity by 2040, within a renewable energy target of 40% to 50%.
• International partnerships and competing tandem technologies are shaping the race toward commercial production.