Message framing to promote solar panels

The study addresses how to increase retail consumer adoption of large-scale green technologies, specifically residential solar panels, which are essential for achieving renewable energy targets (e.g., Paris Agreement goals). While governments often rely on costly financial incentives, the authors investigate whether non-monetary, scalable behavioral interventions—message framing—can promote serious commitments to adopt solar panels. Prior work on message framing in pro-environmental contexts focuses largely on repeated or low-cost behaviors, with mixed evidence on whether targeting self-interest or environmental benefits is more effective. Large-scale investments entail high up-front costs, planning, and time commitments, making decision processes distinct and raising doubts about generalizing prior findings. The authors test whether framing outcomes for oneself (cost savings vs. earnings) or for the environment (reducing CO2 vs. generating green electricity) increases real-world commitments, addressing the intention–behavior gap by measuring actual initiation of the installation planning process following a feasibility check.

Behavioral interventions have promoted environmentally friendly actions through feedback, defaults, and labeling, often affecting repeated or low-cost behaviors (e.g., energy curtailment, green tariff subscriptions). Evidence on message framing is mixed: some studies find self-targeted frames (e.g., personal benefits) more effective, while others find environmental appeals effective. Decision-making for large-scale investments differs due to financial risk, planning, and resource demands. Theoretical underpinnings include self-interest motives, loss aversion, and moral/identity motives for environmental preservation. Prior research suggests cost-savings framing can be persuasive, but most evidence comes from contexts outside large-scale investments and often relies on self-reports, which are subject to the intention–behavior gap. This gap may be especially wide for solar panels due to feasibility and economic constraints, motivating field evidence with behavioral outcomes.

The authors conducted a 14-day, large-scale randomized controlled field experiment at a leading nationwide e-commerce retailer in the Netherlands (March 22–April 5, 2021). Visitors to the retailer’s solar panels webpages (N = 26,873) were randomly assigned to one of four message frames displayed persistently in a prominent call-to-action box throughout their visit: (1) Self-Save: “Save on average € 813 per year”; (2) Self-Earn: “Earn on average € 813 per year”; (3) Environment-CO2: “Reduce CO2 emissions”; (4) Environment-Green: “Generate green electricity.” Messages targeting oneself used concrete monetary values to highlight direct financial benefits; environmental messages used abstract phrasing without numbers to emphasize collective environmental gains, consistent with prior literature and supported by a preregistered scenario-based online experiment. No other aspects of the website (product, price, layout) changed during the experiment. There was no opt-in bias or financial incentivization. Outcome measure: serious commitment to adopt solar panels, operationalized as completion of an adoption form that includes a feasibility check and triggers the planning process, requiring personal and property information—thus going beyond mere intention. Baseline commitment rate in the two weeks prior was 3.8%. Additional customer-level data (province, device type, weekday/time) were collected for controls. Statistical analysis: a logistic regression with condition-specific intercepts estimated commitment probabilities per condition; inverse-logit transformations yielded estimated commitment rates. Robustness checks included alternative model specifications (probit, linear probability), varying reference conditions, restricting to customers located within the Netherlands, and adding fixed effects for device type and weekday. Ethics approvals were obtained (RSM IRB ETH2122-0290 for field; ETH2122-0288 for the online scenario experiment). A supplementary preregistered online experiment (N = 1000, Netherlands) examined concreteness vs. abstractness across self- and environment-targeted frames and validated message comparability.

• All four message frames increased commitment rates relative to the pre-experiment baseline (3.8%). Observed commitment rates during the experiment: Self-Save 5.32%; Self-Earn 4.17%; Environment-CO2 4.12%; Environment-Green 3.98%. The Self-Save frame was the most effective, yielding a 40% higher commitment than baseline and 30% higher than the average of the other three messages. - Logistic regression (log-odds coefficients; N = 26,873): Self-Save coef = -2.88 (SE = 0.05, t = -53.60, P < 0.001, 95% CI [-2.99, -2.78]) corresponding to 5.32% estimated commitment; Self-Earn coef = -3.13 (SE = 0.06, t = -51.89, P < 0.001, 95% CI [-3.26, -3.02]); Environment-CO2 coef = -3.15 (SE = 0.06, t = -50.44, P < 0.001, 95% CI [-3.27, -3.03]); Environment-Green coef = -3.18 (SE = 0.06, t = -50.68, P < 0.001, 95% CI [-3.31, -3.06]). Non-overlapping 95% CIs show Self-Save significantly outperforms the others. Results remain robust with additional controls and alternative specifications. - Environmental impact extrapolation (assumptions: average household electricity 2.81 MWh/year; 0.71 t CO2 per MWh; committed households proceed to installation): Self-Earn would yield 29,136 annual commitments saving 58,272 t CO2/year; Self-Save would yield 37,171 commitments saving 74,342 t CO2/year—an additional 16,070 t CO2 saved per year (27.5% more) versus Self-Earn.

The field experiment demonstrates that message framing can causally increase real-world serious commitments to adopt solar panels for a large-scale, high-stakes purchase. Frames emphasizing personal financial benefits are more effective than environmental benefit frames, consistent with the prominence of economic considerations and loss aversion in high-cost decisions. Framing as cost savings (“Save …”) appears particularly persuasive, possibly because consumers associate savings with avoiding losses. Environmental frames, while potentially motivating initial interest, were less effective at prompting the decisive step of initiating installation planning. The findings extend behavioral intervention literature by showing that scalable, non-monetary message framing can influence high-commitment investments, bridging the intention–behavior gap by using a behavioral outcome in a real-world setting. These insights can guide retailers and policymakers in crafting communication strategies to accelerate adoption of clean-energy technologies.

Message framing is a cost-efficient, scalable tool to promote serious commitments to install residential solar panels. Among tested frames, highlighting personal cost savings produced the strongest effect, outperforming both earnings-focused and environmental frames. The study contributes field-based causal evidence for large-scale green technology adoption and demonstrates substantial potential environmental benefits from effective framing. Future research should test generalizability across countries with different policy environments, examine other green technologies (e.g., heat pumps, home storage, EVs), refine message content (e.g., granularity, timing, personalization), and link commitments to completed installations to assess downstream outcomes.

• External validity: Website visitors may be more interested in solar panels than the general public. - Message comparability: Wording differs across self vs. environmental frames; choices were theory-driven and supported by a supplementary experiment, but direct comparability is imperfect. - Outcome measure: Serious commitment (post-feasibility check initiation of planning) rather than completed installations; chosen to avoid supply/installation idiosyncrasies. - Context specificity: Conducted in the Netherlands where incentives (e.g., net metering, subsidies) exist; effects may vary in other policy contexts. - Environmental messages used abstract phrasing without numbers, whereas self-focused messages used concrete monetary values; though justified by literature and validated online, this design choice may influence relative effectiveness.