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Community Solar and Low-income Solar Adoption
Last registered on August 28, 2017


Trial Information
General Information
Community Solar and Low-income Solar Adoption
Initial registration date
August 28, 2017
Last updated
August 28, 2017 5:57 PM EDT
Primary Investigator
Duke University
Other Primary Investigator(s)
PI Affiliation
Duke University
PI Affiliation
Yale University
Additional Trial Information
In development
Start date
End date
Secondary IDs
The market for residential solar panels in the United States is growing rapidly, bolstered by substantial government support at the federal, state, and local levels. Yet there are concerns that this support is primarily benefiting wealthier households, due to different electricity rates, liquidity constraints, landlord-tenant issues, length of tenancy, and perhaps even preferences (Borenstein and Davis 2016, Borenstein 2017). Accordingly, there has been increasing interest by policymakers and other stakeholders in expanding the adoption of solar to low and moderate income (LMI) households.

Community shared solar (henceforth, “community solar”) can help reduce up-front costs of installation, and also removes the need for a rooftop suitable for solar. It also allows households to still leverage economies of scale when they themselves have lower electricity needs. Thus it may be more attractive to LMI households. Furthermore, by providing a product that expands the markets to households that may not be able to install rooftop solar, we expect to see additional word-of-mouth and thus more total adoption of both community solar and rooftop solar.
External Link(s)
Registration Citation
Bollinger, Bryan, Kenneth Gillingham and Steven Sexton. 2017. "Community Solar and Low-income Solar Adoption ." AEA RCT Registry. August 28. https://doi.org/10.1257/rct.2400-1.0.
Former Citation
Bollinger, Bryan et al. 2017. "Community Solar and Low-income Solar Adoption ." AEA RCT Registry. August 28. http://www.socialscienceregistry.org/trials/2400/history/20937.
Sponsors & Partners

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Experimental Details
In each municipality we are running a behavioral intervention designed to encourage solar adoption. This intervention is called a "Solarize" campaign, and it involves a roughly 18-week campaign, a single chosen solar installation company (based on a competitive bidding process), discount pricing, a kick-off event, solar open houses, tabling at town events, designated volunteer solar ambassadors who coordinate the campaign with SmartPower. The intervention is specifically designed to foster word-of-mouth and social interaction effects. The difference between the two types of campaigns we will run is that one will include a focus on community solar, as well as rooftop solar, in all of the materials given by SmartPower to the ambassadors and potential solar customers.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
The key outcome variables are solar adoption (both rooftop and community solar), and mediating and moderating factors that influence adoptions such as word of mouth.
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Municipalities will be randomly assigned (after first matching towns for each treatment arm) to one of two campaign types. The sample size for the first round is 16 treated plus 8 control municipalities. Starts will be staggered with the matched towns starting at approximately the same time.

SCE&G collects data on all residential solar installations in their coverage area as well as the community solar adoptions.
Experimental Design Details
Randomization Method
Coin flip to assign towns after initial matching.
Randomization Unit
Randomization is at the municipality level.
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
24 municipalities
Sample size: planned number of observations
24 municipalities
Sample size (or number of clusters) by treatment arms
8 municipalities receive rooftop campaign
8 municipalities receive rooftop+community solar campaign
8 municipalities are in the control
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
Yale Institutional Review Board
IRB Approval Date
IRB Approval Number
Analysis Plan

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Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)