Evaluating diffusion in policy designs: A study of net metering policies in the United States

In the United States, some of the most important environmental policy innovations of the past decades have occurred at the state level. Net metering policy is one kind of policy that states have widely adopted in support of decarbonization goals. The widespread adoption of net metering policies varying in policy design, defined here as policy content, offers an opportunity to investigate to what extent policies that diffuse widely bear comparable designs, and furthermore, what factors influence diffusion in policy designs. Availing these opportunities, in this paper, we investigate (1) how (dis-)similar the designs of American states' original net metering policies were; and (2) what factors explain the diffusion of policies that share similar design elements. To support our investigation, we model using event history analysis in a directed dyad setting, the factors that explain differential duration to adoption of net metering legislation containing specific elements of design by policy receiver states. We find that bipartisan legislatures are more likely to adopt the majority of design elements. This suggests that net metering appeals to policy makers across the political spectrum and that the latter compromise in integrating elements of policy design that benefit or burden different constituents. We also find that over time, states become less likely to emulate policy designs from jurisdictions whose citizenry embraces dissimilar values, suggesting that policy makers learn to tailor incentives to their local policy targets.