We estimate Arizona residents' Willingness to Pay (WTP) to invest in a solar energy research and development fund using data obtained from a Dichotomous-Choice Contingent Valuation mail survey. We examine differences in WTP estimates using different categorizations for respondent uncertainty. We also employ both commonly used Maximum Likelihood and less frequently applied Bayesian estimation techniques. We find that respondent uncertainty has an economically significant impact on WTP estimates, while WTP estimates are robust to different estimation techniques. Our robust specification with strict uncertainty coding indicates the average Arizona household is WTP approximately $17 per month to invest in research and development in solar energy. (C) 2012 Elsevier Ltd. All rights reserved.