Does localized imitation drive technology adoption? A case study on rooftop photovoltaic systems in Germany

• We analyze the spatio-temporal diffusion of rooftop-photovoltaics in Germany.
• We employ an epidemic diffusion model which we enhance by a spatial component.
• We find that imitative adoption behavior is important for explaining PV adoption.
• The imitative adoption behavior is highly localized (in the range of 1 km).

The purpose of this paper is to illuminate the spatio-temporal diffusion of rooftop household photovoltaic installations in Germany and to test whether localized imitation drives their adoption. Our study is based on a unique data set of some 576,000 household photovoltaic systems installed in Germany through 2009. We employ an epidemic diffusion model which includes a spatial dimension, and control for temporal and spatial heterogeneity. According to our results, imitative adoption behavior is highly localized and an important factor for the diffusion of household photovoltaic systems.