This study explores the joint impacts across the power system of distributed energy resources (DER) that could be deployed in utility distribution systems through an analysis of generation, transmission, and distribution expansion and costs driven by DER adoption. We identify six adoption scenarios that combine deployment levels of rooftop solar photovoltaic modules (PV), electric vehicle charging (EV), and battery storage in residential and commercial customers connected to representative feeders in Indiana by 2025 and 2040. Indiana is a good proxy for many U.S. states with low current DER adoption but potentially high future growth. The economic value of DER is assessed by developing capacity expansion and power flow analysis of the generation and distribution segments, respectively, under future hourly demand assumptions based on each adoption scenarios. Results for the distribution system power flow simulations show that voltage violations are relatively rare. Voltage violations can be mitigated at a very low cost using a combination of smart inverters in future rooftop PV systems and voltage adjustments in the feeder heads. Line loading issues are minimal, with only 0.2% of simulation hours showing loading levels above 100% of capacity. Generation capacity impacts are driven by unmanaged EV charging and could be mitigated with charging management. We estimate that the incremental rate impact from power system investment and operation of increased DER adoption in Indiana will be between −1.6% to + 2% in 2025 and + 0.2% to + 15% in 2040 relative to the base case.