Decarbonization policies have accelerated global adoption of plug-in electric vehicles (PEVs), presenting challenges for power distribution systems (DS). This study assesses the grid impacts of large-scale PEV and distributed photovoltaic (PV) integration using a real-world DS case from Stockholm County, Sweden. A Monte Carlo (MC) simulation framework models the stochastic, uncontrolled charging behavior of PEVs based on real travel patterns, considering both residential and commercial charging, at penetration levels up to 100%. To demonstrate the framework’s application, a real case study explores how solar PV can mitigate PEV-induced grid impact and enhance hosting capacity across seasons. Results show limited synergy during winter due to low solar availability, with a 2% voltage improvement during summer peak hours. The methodology provides valuable insights for municipalities, DS operators (DSOs), and policymakers planning the sustainable integration of electric mobility and decentralized renewable energy into existing grids.