By AFP and Focus | 2025-07-24

TOKYO -- Japan is investing heavily in a new kind of ultra-thin, flexible solar panel that it hopes will help it meet renewable energy goals while challenging China's dominance of the sector.

Pliable perovskite panels are particularly suited for mountainous Japan, where flat land for traditional solar farms is scarce. A key component, iodine, is something Japan produces more of than any country except Chile -- making it well positioned for domestic production.

The technology does face challenges. Perovskite panels contain toxic lead, currently generate less power and have shorter life spans than do silicon counterparts.

But with a goal of net-zero emissions by 2050 and a desire to break China's solar supremacy, Japan sees strategic value.

Perovskite cells are "our best card to achieve both decarbonization and industrial competitiveness," Minister of Economy, Trade and Industry Yoji Muto said in November. "We need to succeed in their implementation in society at all costs."

To accelerate deployment, the government is offering incentives, including a ¥157-billion ($1 billion) subsidy to Sekisui Chemical for a factory expected to produce enough panels by 2027 to generate 100MW -- enough to power 30,000 households.

By 2040, Japan plans to install perovskite panels capable of generating 20GW, equivalent to about 20 nuclear reactors. This would support its goal of meeting up to 50% of electricity demand from renewable sources by that year.

Japan is also targeting solar power -- including both perovskite and silicon cells -- to supply up to 29% of its electricity needs, up from 9.8% in 2023.

"To increase the amount of renewable energy and achieve carbon neutrality, I think we will have to mobilize all the technologies available," said Hiroshi Segawa, a solar technology specialist at the University of Tokyo.

"Perovskite solar panels can be built domestically, from the raw materials to production to installation. In that sense, they could significantly contribute to things like energy security and economic security," he told AFP.

Maximizing renewable energy

Silicon solar panels are made of thin wafers that are processed into cells that generate electricity.

They must be protected by reinforced glass sheets and metal frames, making the final products heavy and cumbersome. Perovskite solar cells, however, are created by printing or painting ingredients such as iodine and lead onto surfaces like film or sheet glass.

The final product can be just 1mm thick and 1/10 the weight of a conventional silicon solar cell.

Perovskite panels' malleability means they can be installed on uneven and curved surfaces, a key feature in Japan, where 70% of the country is mountainous.

The panels are already being incorporated into several projects, including a 46-story Tokyo building to be completed by 2028.

The southwestern city of Fukuoka has said it wants to cover a domed baseball stadium with perovskite panels.

And major electronic brand Panasonic is working on integrating perovskite into windowpanes.

"What if all of these windows had solar cells integrated in them?" said Yukihiro Kaneko, general manager of Panasonic's perovskite photovoltaic development department, gesturing to the glass-covered high-rise buildings surrounding the firm's Tokyo office.

That feature would allow power to be generated where it is used, and reduce the burden on the national grid, Kaneko added.

While perovskite panels remain far from mass production, the technology is advancing quickly. Some prototypes can perform nearly as powerfully as silicon panels, and their durability is expected to reach 20 years soon.

Japan could have a capacity of 40GW from perovskite by 2040, while the technology could speed up renewable uptake elsewhere, said Segawa.

"We should not think of it as either silicon or perovskite. We should look at how we can maximize our ability to utilize renewable energy," he added.

"If Japan could show a good model, I think it can be brought overseas."

China's grip

Tokyo wants to avoid a repeat of the past boom and bust of the Japanese solar business.

In the early 2000s, Japanese-made silicon solar panels accounted for almost half the global market.

Now, China controls more than 80% of the global solar supply chain, from the production of key raw material to assembly of modules.

In 2024, 94.9% of Japan's solar panels were imported -- mostly from China -- according to the Photovoltaic Energy Association, as cited by the Sankei Shimbun.

China's dominance of the sector has drawn security concerns.

Japan in May launched an investigation into Chinese-made solar panels over fears that they contained hidden communication devices that could disrupt the nation's power grid, the South China Morning Post (SCMP) reported.

The inquiry followed earlier findings by authorities in the United States and Europe, who uncovered undeclared communication components embedded in Chinese solar inverters.

These could allow unauthorized remote access, bypassing security firewalls and potentially disrupting national energy infrastructure, analysts said.

In response, the Japanese government is now examining whether similar components exist in imported panels sold domestically.

"For too long the Japanese government has had no real policy on imports so this is something of a wake-up call," Toshimitsu Shigemura, a political scientist at Tokyo's Waseda University, told the SCMP.

"I am sure they will be very worried and they will be looking at these imported solar panels very closely," he said.