Solar energy is a field that has grown rapidly in the world in recent years to solve the energy crisis and respond to climate change. Vietnam is a country with renewables energy potential including solar power and is pursuing net zero emissions target by 2050. This study explores factors affecting the residents' intention to buy solar water heater in Hanoi, Vietnam. We used theory of planned behaviors and technology acceptance model to build research model and hypotheses. A community survey was conducted with 450 households in 3 districts using cluster sampling method to collect information. We conducted descriptive statistical analysis, Cronbach's Alpha test, exploring factor analysis, conformity factor analysis and regression to identify and evaluate the impact of factors on solar water heater consumption intention. The results showed that there were significant factors affecting people's intention to buy solar water heater including attitude, perceived usefulness, price perception, social influence and financial support in which attitude is the most influential factor. Regarding social characteristic of respondents, we also found positively significant relationship between income, education level and intention to use solar heater. Recommendations for government and business included increasing awareness of the benefits and economic feasibility of renewable energy devices to consumers through social media, implementing financial incentives to support clean energy consumption behavior, and strengtheing the emergence of local solar evangelist groups in the communities. Future research can expand to other cities and explore more indirect factors affecting the green energy consumption behavior of Vietnamese residents.