Will nonowners follow pioneer consumers in the adoption of solar thermal systems? Empirical evidence for northwestern Germany

In Germany, solar thermal systems (STSy) have only diffused to a minor extent as yet. This paper analyzes which demand side factors are decisive for the further proliferation of this environmentally benign technology. Making use of a consumer survey in northwestern Germany in 2007, we examine the following parameters: positive environmental attitude, knowledge of the applicability of STSy to satisfy consumer needs, and the presence of STSy among peer consumers. Drawing upon theoretical foundations from innovation economics and social psychology, we posit that these variables play a different role at distinct stages of the systems' diffusion process. Among nonowners, concrete plans to purchase such a system within the next two years are distinguished from the general interest to invest in this technology within the next five years. Probit models are estimated to test our hypotheses. Our results do not indicate a strong take-off of product diffusion within the next few years. By generating interest for the product, environmental attitude and knowledge as well as household income are important determinants of prospective adoption on the part of nonowners. However, it is only peer group behavior that appears to function as a trigger for the diffusion of this technology.