Compared to Mature Overseas Markets, BIPV Has Significant Potential for Increased Penetration in the Future. In developed countries, building-integrated photovoltaics (BIPV) began earlier, with many countries implementing various incentive policies and development plans as early as the late 20th century. For instance, Germany, Italy, Japan, and the United States have all established "Solar PV Roof Programs," setting clear targets for building PV installation capacities in the coming years.