In a study conducted by researchers from the University of Lausanne and the Swiss Federal Institute of Technology, it was found that homeowners are more like to install rooftop solar PV systems when individuals are informed about how much money they could have saved by adopting this technology sooner.

The research involved tracking 600 homeowners in Schaffhausen, Switzerland, for four months in 2022. The primary finding was that nudging, a method of gently proposing an idea without a mandate or incentive, was effective in promoting rooftop solar adoption. The success of nudging was significantly influenced by whether homeowners were motivated by the potential savings they could make with solar PV.

The study involved two types of personalised letters sent to homeowners. One letter emphasised the prosocial benefits of rooftop solar, highlighting contributions to climate protection. The other letter focused on self-interest, informing homeowners about the potential solar electricity and cost savings they were missing out on. Both letters invited homeowners to receive PV consulting sessions and request installation offers.

The results showed that the self-interested approach had a greater impact on motivating homeowners to act, with a 15-percentage point increase in the likelihood of taking action. In contrast, a group that received a letter emphasising social norms and neighbours' installations produced a smaller, though still significant, effect with about a 6.5 percentage point change.

The research highlights the potential of nudging as an effective government instrument to promote solar energy adoption without the need for significant policy changes or subsidies. It also has implications for achieving Switzerland's net-zero fossil fuel target by 2050.

The findings were presented in the study "Governments can nudge household solar energy adoption: Evidence from a field experiment in Switzerland," published in Energy Research & Social Science. Switzerland has seen a growing interest in PV installations, with over 1 GW installed in 2022, contributing to the country's renewable energy goals.

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