The Tokyo metropolitan government said Thursday it will introduce a system requiring newly built homes to be fitted with solar panels from fiscal 2025 in a bid to reduce carbon emissions from the household sector.The first mandate of its kind in Japan comes as a revised ordinance on environmental security to introduce the system was passed Thursday by a majority vote on the final day of a regular Tokyo metropolitan assembly session.According to the metropolitan government, major housing construction firms will be required to install solar panels on buildings with a total floor area of less than 2,000 square meters.The metropolitan government estimates that the 980,000 yen ($7,200) initial cost for installation of the 4-kilowatt panels can be covered within 10 years from electricity sales revenue and can be further reduced down to six years with subsidies it will provide.Koike said she wanted to promote decarbonization efforts and "go forward while deepening everybody's understanding.""