Climate change projections show Cambodia becoming hotter with increased rainfall in the wet season and reduced rainfall in the dry season. These changes will make it difficult for farmers, who have already reported that the climate has become less predictable, to select the optimal time to plant rice and other crops. The Scalingup of Renewable Energy Technologies (S-RET) project targeted 8,000 smallholder farmers in five provinces comprising 980 villages, particularly women and poor households in remote areas, who lack access to modern, affordable, and reliable energy sources. Building on strong collaboration with and learning from existing projects, engaging small and medium sized enterprises through a Call for Proposal, and active women’s participation with innovative ideas from private sector, the project succeeded in introducing appropriate and affordable RET for smallholder agriculture in rural areas of Cambodia. As a result, the project contributed to reducing greenhouse gas (GHG) and improved climate resilience for the rural communities by investing in economically viable RET for agriculture production, processing, and post-harvest activities. Key lessons learned from this project are transparent grant mechanism for small and medium sized enterprises, scaling up and strengthening sustainability of RET by private sector initiatives, and knowledge sharing for awareness raising of RET.