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The Yomiuri Shimbun An employee at a homebuilding company discusses solar panels with customers in Koganei, Tokyo, on March 23.
The Yomiuri Shimbun
6:00 JST, April 1, 2025
New homes and residential buildings in Tokyo must come equipped with solar panels as of April 1, when a revised ordinance from the metropolitan government takes effect.
The original ordinance was the first of its kind in Japan, and after it was enacted, other cities and municipalities began requiring solar panels be installed. However, disposal of the panels is set to be a major issue going forward.
Making a model city
On March 23, a 37-year-old woman living in Koganei, Tokyo, visited a home display village in the area and learned about residential solar panels from an employee of homebuilder AQ Group Co.
“If you have the [solar] panels installed, they will cover a considerable amount of your power bill, and you will have electricity even in a blackout,” the employee told the woman. She was thinking of having solar panels installed on the roof of her new house, which will be built in Tokyo.
“Solar power is environmentally friendly and will probably help me save on energy costs, too,” she said.
According to AQ Group, since the ordinance was enacted in December 2022, more of its customers have wanted solar panels installed, and the company is now installing the panels on 90% of the houses it sells.
“The ordinance was an opportunity for people to get a better understanding of solar power generation,” said the manager of the company’s Koganei branch.
Although solar power provides clean, carbon-free energy, Tokyo has few open spaces large enough to build a major solar power plant. That led the metropolitan government to focus on the roofs of people’s homes in revising the ordinance. It aims to raise the capital’s installed solar energy capacity from 720,000 kilowatts in fiscal 2022 to 2 million kilowatts or more in fiscal 2030.
The metropolitan government has also started providing technical support for the private sector.
“I hope to realize a carbon-free city that is a model for the rest of the world,” Tokyo Gov. Yuriko Koike said at a press conference on Friday.
The Kawasaki municipal government is also making solar panel installation mandatory for new homes and residential buildings as of April 1. The city has secured ¥800 million in subsidies for solar panel installations in fiscal 2025, four times more than in fiscal 2024.
“We want to start doing everything we can do now to help with decarbonization,” said an official for the Kawasaki municipal government.
Other cities considering mandatory solar panels include Sendai, Sagamihara in Kanagawa Prefecture and Matsudo in Chiba Prefecture.
The life span of a solar panel is said to be about 20 years. In the 2030s, there could be 2,300 tons of solar panels to be disposed of, and in the 2040s this number could double to about 4,600 tons, according to an estimate by the Tokyo metropolitan government.
Solar panels contain both valuable metals, such as silver and copper, and toxic substances, such as lead and arsenic. In Japan, there are currently only 10 facilities where the panels can be taken apart and recycled, with many panels being thrown in landfills.
In fiscal 2025, Tokyo will launch support for recycling companies that introduce equipment for the panels.
“Even if we try to improve our work capacity, there’s a limit to what a single company can do,” said a senior employee of Hamada Co., which runs a disassembly plant in Ota Ward, Tokyo. “The public and private sectors need to cooperate with each other and create an effective recycling network.”
Twice as many roofs
The central government is also aiming to grow the solar power supply. It wants to boost the percentage of new houses with solar panels nationwide from 31.4% in fiscal 2022 to 60% in fiscal 2030.
From April, the government will require all new houses to comply with its energy-saving standard. Under its system, it will be easier for houses to meet the standard if they are equipped with solar panels.
From fiscal 2027, the government will require major homebuilders to work toward installing solar panels on 37.5% of pre-built homes and 87.5% of custom-built homes, excluding extremely small houses and houses in areas with heavy snow in winter.
