Expansion of distributed solar photovoltaic (PV) and natural gas-fired generation capacity in the United States has put a renewed spotlight on methods and tools for power system planning and grid modernization. This article investigates the impact of increasing natural gas-fired electricity generation assets on installed distributed solar PV systems in the Pennsylvania-New Jersey-Maryland (PJM) Interconnection in the United States over the period 2008-2018. We developed an empirical dynamic panel data model using the systemgeneralized method of moments (system-GMM) estimation approach. The model accounts for the impact of past and current technical, market and policy changes over time, forecasting errors, and business cycles by controlling for PJM jurisdictions-level effects and year fixed effects. Using an instrumental variable to control for endogeneity, we concluded that natural gas does not crowd out renewables like solar PV in the PJM capacity market; however, we also found considerable heterogeneity. Such heterogeneity was displayed in the relationship between solar PV systems and electricity prices. More interestingly, we found no evidence suggesting any relationship between distributed solar PV development and nuclear, coal, hydro, or electricity consumption. In addition, considering policy effects of state renewable portfolio standards, net energy metering, differences in the PJM market structure, and other demand and cost-related factors proved important in assessing their impacts on solar PV generation capacity, including energy storage as a non-wire alternative policy technique.