In recent years, the diffusion of photovoltaic distributed generation (PVDG) has played a key role in achieving climate and energy policies goals. This increase stems from both the decline of technology costs and also from the support policies adopted worldwide. Yet, the achieved diffusion levels and the related impacts vary across locations. By applying a new analytical approach to thirteen international case studies, the study provides an exhaustive systematization of policies and regulatory adjustments of PVDG diffusion, focusing on the electricity distribution sector. The goal is to identify possible common patterns and path dependence trajectories. The results show that the policy impacts and the regulatory adjustments vary mostly according to the category of the support policies implemented. In countries where feed-in tariffs (FiTs) have been introduced, the main concern is the increasing cost of policies maintenance. The regulatory adjustments are mostly PV specific involving, in most cases, the reduction of the FiTs. In regions where net metering policies have been implemented, otherwise, the impacts are predominantly related to cost-shifting issues, thus requiring regulatory changes which can also be prosumers’ specific, but that attempt to correct allocative distortions through electricity tariffs.