We conducted the first test-retest analysis on willingness to pay (WTP) estimates for different types of solar energy. While there have been numerous examinations of WTP estimate stability over a short period, there is limited evidence regarding the stability of these estimates over an extended period, as well as in test-retest scenarios before and after the implementation of an energy policy. Using discrete choice experiment surveys, we collected initial data from 404 respondents through mixed-mode surveys in 2017, supplemented by 719 online respondents in the retest in 2023. We assess the temporal stability of WTP over a six-year period in New Mexico. Using conventional logit models, our results demonstrate stable preferences for Renewable Portfolio Standards (RPS), with WTP ranging from $0.67 to $0.69 for each one percent increase, remaining consistent despite policy alterations. Utility-scale solar energy gained preference over rooftop solar, especially at higher RPS levels (80% by 2040). Noteworthy shifts included a substantial increase in willingness to accept restrictions on credit storage for rooftop solar owners, indicative of changing perspectives due to increased participation of rooftop solar owners in the retest. Furthermore, we observe a significant increase in WTP for decreasing water usage from fossil fuel-based electricity generation, reflecting heightened environmental awareness. Attitudes toward advanced smart meters evolved from strong support in the test phase to nonsignificant in the retest, suggesting changing sentiments regarding technological interventions. Similarly, we find growing dissatisfaction with the existing state of energy policy in New Mexico. These findings provide crucial insights into the evolving landscape of public preferences concerning solar energy policies, informing future policy decisions and public engagement strategies.