Tokyo is mandating that all new homes in the city be built with rooftop solar panels starting in 2025.

Tokyo is the first Japanese city to require rooftop solar on new homes. The mandate, which goes into effect in April of 2025, applies to roughly 50 large construction companies, which will be required to install solar arrays on homes with up to 2,000 square meters of floor space.

Since the 2011 Fukushima nuclear disaster, Japan has dramatically scaled down emissions-free nuclear power, turning instead to heavily polluting coal. Local leaders hope a buildout of rooftop solar will help clean up the power grid.

Tokyo is aiming to cut emissions in half by 2030, and households account for 30 percent of the city’s energy use, The Japan Times reports. But just 4 percent of Tokyo buildings suitable for rooftop solar are currently equipped with solar arrays, Reuters reports.

“In addition to the existing global climate crisis, we face an energy crisis with a prolonged Russia-Ukraine war,” Risako Narikiyo, a member of the regional political party Tomin First no Kai, told the city assembly. “There is no time to waste.”