From next year, the Japanese government will mandate the installation of rooftop solar panels on factories, retail outlets, warehouses, and local government buildings that consume large amounts of fossil fuels, as part of its strategy to accelerate decarbonisation and expand the country’s renewable energy capacity.
The Ministry of Economy, Trade and Industry plans to revise existing legislation to require solar panels on sites using more than 1,500 kilolitres of crude oil equivalent annually. The rule will initially apply to around 12,000 facilities, increasing to approximately 14,000 by 2027.
Businesses will be obligated to report annually on the area and capacity available for solar panel installation, with fines imposed for non-compliance.
As part of the rollout, the government will promote the use of perovskite solar cells—an emerging technology known for its high efficiency, low cost, and lightweight properties. Japanese firms such as Sekisui Chemical Industries are already advancing in this field, and the domestic availability of key materials offers strategic advantages for energy and economic security.
The move follows Japan’s revised Basic Energy Plan, announced in February, which targets a significant increase in the share of solar power from 9.8% to 23–29% of the total energy mix by 2040. The Japan Institute of Energy Economics estimates that rooftop solar capacity on commercial and industrial buildings could reach 16–48 terawatts, equivalent to 2–5% of Japan’s total electricity generation—comparable to output from multiple nuclear reactors.
