Best–Worst Scaling (BWS) is applied to assess Japanese consumer preferences for combination of power generation sources and a power producer and supplier (PPS). Although the concept of renewable energies has been disseminated, the PPS is still unfamiliar to most of the Japanese consumers. BWS has advantages in obtaining information on preferences by identifying “best” and “worst” options. An online questionnaire survey was conducted in 2020 and its sample size was 2,496. BWS object case and BWS multi-profile case are both applied in this study. Results of BWS object case reveal that solar PV is the most important factor. Conversely, other renewables and thermal power generation are less important. Nuclear power is a fairly low rating. Random parameters logit analysis reveals the difference by generations, gender and residential solar PV installation. BWS multi-profile case reveals that different results are obtained if a plan with 100% renewables is added to the generic three alternatives. Random parameters logit estimates of multi-profile case demonstrate the preference heterogeneity of renewables though its mean parameter is not statistically significant. The evaluation of coal-fired and nuclear power generation is low.