Continuously increasing demand of microgrids with high penetration of distributed energy generators, mainly renewable energy sources, is modifying the traditional structure of the electric distribution grid. Major power consumer countries are looking for alternative energy sources to avoid the impact of higher fossil fuel consumption. Thus, different policies have been promulgated to promote renewable energy technologies (RETs) and distributed energy resource (DER) deployment and are encouraging technological innovation. These policies aim to reduce greenhouse gas (GHG) emissions and achieve energy security and independence to meet an ever-increasing electricity demand. Many studies have been performed on the successful integration of RET and DER operation and control, protection and stability issues, all simultaneously and satisfactorily implemented during feasible microgrid operation. However, apart from the technical challenges, few microgrid studies exist on effective policies and incentives for microgrid promotion and deployment. This survey investigates the policy, regulatory and financial (economical and commercial) barriers, which hinder the deployment of microgrids in the European Union (EU), United States (USA) and China. In this paper, a clear view on microgrid policy instruments and challenges are investigated to aid future developments.