This paper presents a novel approach to estimate the overloading from PV power production and EV charging over large geographical areas without the use of a full grid model and without end-customer consumption data, which is often not available externally to the DSO. Instead, spatiotemporal models of PV production and EV charging are used together with footprints of building and parking spaces and LiDAR aerial data. A case study on a large Swedish city is presented where 100% EV and PV penetrations with various charging powers and charger-accessibility were simulated. Data of driving patterns in the city and weather data are used to calculate time-series that are added to the aggregated consumption and allocated to the simplified (70 kV) regional grid within the city. The method thus allows to evaluate the impacts of high PV and EV scenarios on the high voltage (HV)/medium voltage (MV) substations. The method also enables assessment of the maximum 10-min power flow that can be allowed with full N-1 redundancy of the transformers.