Seven Kansai prefectures have agreed to participate in a project proposed by Softbank founder Masayoshi Son to turn unused farmland into sites for solar energy panels that would eventually provide the same amount of electricity as 50 nuclear reactors.

Thursday's decision by the Union of Kansai Governments, which consists of Shiga, Kyoto, Osaka, Hyogo, Tottori, Wakayama and Tokushima prefectures, means 26 prefectures have agreed to participate in the project.

Under the plan, 10 areas in Japan would be chosen to build mega-solar panels that would provide electricity to surrounding areas. When operational, they would generate about 50 million kw to surrounding prefectures, or about 20 percent of Japan's total electricity demand. Son hopes to complete the project within the next two decades.