In recent years, the development of renewable energy capacities has garnered increasing global attention due to its potential for delivering clean and uninterrupted energy supply. Despite substantial inherent opportunities, the adoption of renewable energy in Iran and several other countries has experienced limited progress. This study aims to identify and analyze the barriers to renewable energy expansion in Iran using a qualitative thematic analysis approach and a two-round Delphi method. Data were collected through in-depth semi-structured interviews with 17 experts in Iran’s renewable energy sector, selected based on their experience and domain expertise. The analysis yielded 4 primary themes, 10 sub-themes, and 23 barrier concepts. The findings identify four critical dimensions as the main barriers to renewable energy development in Iran: Technology and Infrastructure, Policy and Regulatory, Macroeconomic and Financial Environment, and Social and Cultural Dimensions. Key components include: technological limitations, infrastructure deficits, and institutional weaknesses (Technology and Infrastructure); inadequate government and policy support, alongside regulatory frameworks (Policy and Regulatory); international sanctions, financial constraints, inflation, price instability, subsidies, and pricing mechanisms (Macroeconomic and Financial); and public acceptance and cultural factors (Social and Cultural).