In 2010, the National Renewable Energy Laboratory (NREL), Southern California Edison (SCE), Quanta Technology, Satcon Technology Corporation, Electrical Distribution Design (EDD), and Clean Power Research (CPR) teamed to analyze the impacts of high penetration levels of photovoltaic (PV) systems interconnected onto the SCE distribution system. This project was designed specifically to benefit from the experience that SCE and the project team would gain during the installation of 500 megawatts (MW) of utility-scale PV systems (with 15 MW typical ratings) starting in 2010 and completing in 2015 within SCEs service territory through a program approved by the California Public Utility Commission (CPUC). This report provides the findings of the research completed under the project to date. Research objectives of this project include: Development of distribution and PV system models required to evaluate the impacts of high penetration PV. Identification and development of the necessary distribution system studies and analysis appropriate for determining the impacts of high penetration PV. Development of high penetration PV impact mitigation strategies in the form of advanced inverter functions to enable high penetration PV interconnection. Lab testing of advanced PV inverter functions. Field testing of advanced PV inverter functions.