This paper discusses a procedure for modeling a distribution feeder with large-scale distributed photovoltaic (PV) generation using the analysis tools OpenDSS and CYMDIST, and its extensive validation through comparison with field measurements. The basic distribution system model with high penetration of PV based on extensive geographic information system (GIS) data has been reported in . In this paper, the loads, substation voltage, and PV output are modeled at a finer resolution using data from advanced metering infrastructure (AMI) and a network of data acquisition systems (DAS), and by employing a zone division method. The results from power flow analysis at specified conditions such as highest penetration case as well as results from time series analysis over an extended period of time show good correlation with field measurements. The load allocation process combined with the modeling process outlined in  can be used to study the impact of varying levels of distributed solar PV on the distribution system operation and design.