The transition to low-carbon energy systems is a global imperative, with distributed renewable energy playing a pivotal role. In China, county-wide distributed rooftop photovoltaic (DRPV) systems represent a significant opportunity for rural energy transformation and carbon reduction. However, widespread adoption among rural residents faces substantial social and behavioral barriers. This study employs a novel mixed-methods approach to dissect the complex factors influencing rural households’ participation in DRPV projects. First, we harness large-scale, multi-platform online textual data (2014–2024) to perform dynamic topic modeling using the BERTopic framework, identifying evolving public perceptions related to cost, risk, technology, and policy. These emergent themes are then integrated with the established Unified Theory of Acceptance and Use of Technology (UTAUT) to construct a comprehensive theoretical model. The model is empirically tested using structural equation modeling (SEM) on survey data collected from 828 rural residents in Jiangsu Province. Results indicate that facilitating conditions—primarily shaped by technical perception and government-led safeguards—exert the strongest direct influence on participation behavior (β = 0.582, p < 0.001). Behavioral intention, while significant, shows a weaker effect (β = 0.347, p < 0.001). Social influence emerges as the most potent driver of intention (β = 0.424, p < 0.001), surpassing performance expectancy (β = 0.253, p < 0.001) and effort expectancy (β = 0.301, p < 0.01). Notably, rural residents demonstrate a dual valuation of economic returns and environmental co-benefits. The study concludes that effective DRPV promotion requires a multi-pronged strategy: enhancing institutional support and technical assistance to improve facilitating conditions; leveraging community networks and on-site consultation to amplify social influence; and implementing targeted financial instruments to mitigate cost sensitivity. These findings offer evidence-based policy insights for accelerating rural PV diffusion in China and similar contexts globally.