This research investigates Thailand's renewable energy (RE) innovation program for very small power producers (VSPPs) using diffusion of innovations as a theoretical lens. I investigate the influence of socio-political, economic, industrial, environmental, institutional, innovations and networks determinants that must be considered when setting energy policies and strategies for similar RE initiatives. In order to structure and categorize my source data, I created a multi-determinant analytical framework which forms the basis of my analysis of the seven determinants set out above. By doing so, I added to the existing knowledge base regarding analytical approaches to RE innovations diffusion. I investigate causal connections between these key determinants and the development and prospects for sustainability of the VSPP program. Through the use of my analytical framework, I was able to identify existing gaps in diffusion of innovations theory and other relevant literature; for example, I discovered a number of VSPPs who did not fit into the description of 'innovators' or 'adopters' as defined in diffusion of innovations theory. These participants were actually compelled to adopt the VSPP program due to pressure from local communities and government concerning environmental pollution. This finding discloses a gap in diffusion of innovations theory by showing that some adopters did not have a choice to adopt the program. The VSPP program represents a unique RE initiative in Thailand and the participants, VSPPs and other stakeholders are engaged in the diffusion of innovations process. I also examine, in detail, the reasons why the program appears to be developing at a very slow rate. I also developed analytical tools, such as encapsulating tables which summarise my findings for each of the determinants. These tools further advance the knowledge base with respect to analytical techniques for diffusion of innovations research. The findings reinforce the notion that RE innovations programs, including the VSPP initiative, are better understood when a pluralistic analytical approach is taken which investigates multiple determinants in order to discover what barriers exist that limit program development and how stimulants might be used to counteract them. While the research focused on the VSPP program, in Thailand, the multi-determinant analytical framework may be suitable for investigating RE initiatives in other developing countries.