Promotional Campaign Duration and Word of Mouth in Solar Panel Adoption

Intensive marketing campaigns can be used to increase awareness, consideration, purchase, and word of mouth (WOM) of prosocial products. With expanded interest and belief in how social norms and spillovers might be leveraged to combat climate change, it is critical to understand how campaigns designed to leverage such peer effects can be best designed. In this paper, we study the role of campaign duration in solar photovoltaic adoption using a large-scale field experiment in which we randomly assign communities to campaigns with shorter durations, increasing the marketing intensity to maintain the same total resources per campaign. We find that the longer campaigns generate more WOM and lead to more adoption postcampaign despite a comparable number of installations during the campaigns. The shorter campaigns led to 22.6 fewer installations per town in the two years after the campaigns concluded, leading to a cost per acquisition of $4,367 versus $2,029 in the longer campaigns, the latter being lower than installers’ self-reported acquisition costs and the former being substantially higher. History: Olivier Toubia served as the senior editor. This paper was selected as a finalist in the 2022 Gary L. Lilien ISMS-MSI Practice Prize Competition. Funding: This work was supported by Agence Nationale de la Recherche (ANR) [Grant ANR-17-EURE-0010 (Investissements d’Avenir program)] and the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy [Solar Energy Technologies Office Grant DE-EE0006128]. Supplemental Material: The online appendix and data files are available at https://doi.org/10.1287/mksc.2022.0243