The inclusion of generation through renewable energy sources (RES) to a distribution system has become a critical matter for most utility companies since it is a global goal to improve energy production standards. Taking into account the above context, the conditions in which these energy sources will be connected to the systems must be carefully assessed with the particular focus on the implications that might affect the parameters of power quality and energy management, such as harmonic distortion and the main challenge evaluated in this study: reverse power flow. This document proposes a methodology to evaluate the connection of distributed generation (DG) through photovoltaic panels (PVs) into existing distribution systems. The above to perform characterization of reverse flows for different situations of active and reactive power provided by the PVs in the case study. The main contribution of this methodology allows focusing on the system's losses and currents to detect whether the DG implies reverse power flows in critical scenarios.