For solar industry professionals in China, May 31, 2018, is a day that will live in infamy. At the beginning of 2018, Chinese domestic solar developers were riding a high after reaching a record 53 GW of newly installed solar capacity the previous year. Most sources projected this breakneck pace of new solar construction would continue through 2018. On June 1, 2018, however, the National Development and Reform Commission, Ministry of Finance, and National Energy Agency announced a new policy to lower the solar feed-in-tariff, halt subsidized utility-scale development, and implement a quota for distributed projects. Industry professionals refer to the infamous policy as “531” for May 31, 2018, the day that the solar industry ground to a temporary halt or “freezing point.”