Temporal stability of consumer preferences for solar Energy: A choice experiment study

I conducted the first long-term repeated cross-sectional analysis with identical choice tasks on willingness to pay (WTP) for solar energy, using discrete choice experiments. Initial data was collected from 404 respondents through mixed-mode surveys in 2017, and 719 online respondents participated in the 2023 wave. I assessed the temporal stability of WTP over a six-year period in New Mexico. My findings, based on mixed logit models in WTP-space with sociodemographic and environmental attitude interactions and scale heterogeneity adjustments, reveal selective temporal instability. Preferences for rooftop solar share, monthly credit banking, and the status quo energy plan exhibited significant magnitude changes, while preferences for Renewable Portfolio Standards (RPS), water usage in the electricity sector, and smart meter installations remained stable, though the latter had statistically nonsignificant results. Respondents were willing to pay premiums for policies that increase RPS, expand rooftop solar relative to utility-scale solar, prevent utility restrictions on credit banking, reduce water usage by utilities, and enable online access to electricity information. Sociodemographic interactions revealed that political affiliation, age, and graduate education influence RPS preferences, while higher income affects rooftop solar preferences. Stronger environmental attitudes correlated with higher WTP for RPS and water conservation across both waves. However, environmental premiums for rooftop-over-utility-scale solar and smart meters disappeared by 2023, reflecting technology normalization as adoption scaled from niche to mainstream status. Overall, I observe a downward shift in preferences for solar policies after increased RPS policy implementation.