The Indonesian government has implemented a solar panel policy to overcome a limitation of electrical availability in remote islands. Unfortunately, the prior studies have given a little concern to examine the social effect of the policy. Therefore, this paper addresses the research gap by testing the difference in social impacts of solar cell usage. Before and after analysis was used in this study. This research was conducted using a survey approach on two rural coastal communities in Karimun Regency, Kepulauan Riau, Indonesia. The research was arranged from May to October 2019. The respondent was chosen using simple random sampling. 262 respondents from these regions were voluntarily involved in the survey. Data were analysed using descriptive statistics and a paired sample t-test by applying SPSS. The findings reveal that there are significant differences in communities’ social capital in terms of social relationships, trust, participation in the community, and brotherhood, before and after the policy is applied. Although solar panels provide many conveniences to society, social capital decreases to a lower level than before. The contributions of the research to the theory and practice are discussed.