What drives social contagion in the adoption of solar photovoltaic technology?


This research finds that households, businesses and farms are more likely to install solar panels if others in their neighbourhood have already done so, and in particular if existing installations are highly visible.

Solar panels are expensive and can represent a risky investment. Learning from neighbours appears to spur installation because it decreases these concerns. The research also shows that imitation – in the form of ‘going green’ when others do so – is important in the choice to install solar panels. This effect has already been shown in the adoption of other pro-environmental behaviours.

Policymakers could use these findings to leverage these ‘social contagion’ effects to increase the adoption of solar panel technologies.

Key points for decision-makers

  • Analysis of approximately 60,000 solar photovoltaic installations on homes and businesses in Switzerland shows that installation of solar panels spreads from neighbour to neighbour. The existence of this effect has also been demonstrated in the US (in California and Connecticut) and Germany.
  • The installation of a new panel is likely to lead to 0.08 additional panels per quarter year within approximately 300 metres.
  • Visibility drives the effect. Panels integrated into the side of a building lead to more new adoptions than panels attached to a roof because they tend to be more visible.
  • The effect decreases with distance and with time: the closer or more recent an installation is, the greater the ‘contagion’ effect.
  • Business owners tend to be influenced by the installations of other businesses owners, and farm-holders by other farm-holders. Householders are influenced by all installations.
  • Policymakers could use these effects to spur adoption of solar panel technologies by householders through, for example: installing signposts to emphasise the presence of a solar panel; group pricing of panels at the neighbourhood level; public gatherings to share information on solar panels; ‘electing’ community-level solar ambassadors; and using referrals.
  • Business organisations and local industry clusters could also stimulate adoption by firms by providing a platform for similarly sized businesses or those in the same sector to share experiences and tips.