This paper discusses the detailed procedure for automated construction of a distribution system model using CYMDIST. Information about the distribution system equipments and lines is provided in geographic information system (GIS) data, and load and PV data is obtained by advanced metering infrastructure (AMI). Based on the given data, step by step method to construct the distribution system model is described. The model constructed includes single phase loads, high penetration of single phase solar photovoltaics (PV), and two large three-phase PV. CYMDIST has the ability to execute the three phase unbalanced power flow analysis on the model. Analysis results with and without PV in terms of voltage profiles, KW profiles and KVAR profiles are presented, in order to investigate the impact of high penetration of distributed solar photovoltaics.