Although most studies present willingness to adopt as a pre-adoption facet, very few studies can be found that include pre- and post-adoption willingness factors/conditions in adopting solar energy. This study was carried out to explore public willingness to adopt solar energy in residential areas through the lens of different states (stages) of willingness to adopt, and consequent patterns of social acceptance. This qualitative study found the existence of four states of willingness to adopt solar energy among laypersons and expert Finnish respondents, forming quadrants in the interplay between decision and actions. This gave rise to five segments of customers, most representing the ‘acceptance in principle’ pattern of social acceptance. The results of this study emphasize the necessity for an effective and meaningful approach to those states of willingness to adopt in the growth and diffusion of renewable energy technologies such as solar energy.