Advancing the deployment of solar technologies can yield economic benefits to individuals and benefits to wider segments of society. Although U.S. deployment of rooftop-solar technologies has soared in recent years, most installations have been concentrated among high-income households. Increasing solar deployment among LMI households represents a major opportunity to expand solar’s broader benefits while increasing equitable access to a valuable economic resource. In addition, the existing literature provides very limited information about the specific solar-related motivations and barriers of different socioeconomic groups. Research on energy efficiency and weatherization programs, however, suggests that LMI households may face a range of institutional, political, and social barriers—beyond the financial impediments faced by traditional solar customers—such as lack of information, poor roof suitability, and distrust of the organizations offering such programs. This research also indicates that leveraging social networks can increase program participation. For these reasons, our study focuses on behavioral-based strategies for increasing solar referrals and subsequent solar adoption among LMI households.
Based on the experience of the solar-installation organization that we are partnering with for our study, referrals from existing customers are the most effective pathway to new solar installations. Theories from behavioral economics and psychology may provide insights into ways to motivate these existing customers to expend the minor amount of effort needed to provide referrals, potentially leading to an increase in solar installations.
In brief, we are performing a randomized controlled trial of whether two behavioral interventions—reciprocity and streamlining—cause (1) an increase in referrals provided by existing customers, and (2) an increase in quality referrals, i.e., referrals that translate to leads and successful solar installations. A reciprocity group (n = 2,250) receives a non-contingent reward ($1 in cash) delivered via a referral-solicitation letter. A reciprocity + streamlining group (n = 2,250) also receives a referral form and pre-stamped envelope with the solicitation letter as well as an email with a direct link to a referral website. A control group (n = 2,250) receives referral solicitations without these strategies, in the form of postcards with basic information on how to provide referrals (via a phone number or website) and why it is important (this control group strategy is the current method used by our partner).
Other important methodological details are as follows. The power is sufficient to test our hypotheses in a way that is meaningful for U.S. solar energy. The method for randomizing is similar to stratifying and ensures a balanced panel for all groups. We have IRB approval. Our partner has already implemented the randomization and experiment, but no data have been transferred to the researchers. In fact, to our knowledge, our partner has not examined the data from the experiment.
If our results show an improvement in effort due to reciprocity and/or streamlining, they will have an immediate impact in that our partner may change their referral-request processes in all of the nine states in which it operates, and dissemination of the results through industry conferences likely will affect the methods of similar solar companies in the near term. If our results are roughly consistent with studies testing different versions and applications of reciprocity, they will provide an important link in understanding the underlying mechanism and theory of reciprocity. If our results are not consistent with existing literature, they will lead to research that can define the exact conditions and solicitation approaches that make reciprocity motivating.