This book examines how political institutions, financial architectures, and policy innovations together shape the pace and direction of sustainable energy transitions in developing countries. It highlights how renewable energy aid, green finance, and targeted incentives can unlock low-carbon pathways that advance both climate and development goals. It explores:How democratic quality, governance, and state-owned enterprises influence the effectiveness of renewable energy aid and the behavior of incumbent energy actors. The conditions under which green finance, blended instruments, and subsidies can shift coal-dependent and emerging economies toward cleaner energy systems. The potential for innovation ecosystems, blue economy strategies, and decentralized niche solutions to create new windows of opportunity for context-appropriate renewable technologies. Organized around these themes, the book offers a multi-layered view of sustainable energy transition in the global South. Part 1 investigates the political and institutional landscape, analyzing how regime type, governance quality, and international aid interact to drive renewable energy deployment across more than 100 developing countries. Part 2 focuses on finance and incentives at the regime level, examining shifts from public to private capital, the design of subsidies and green finance instruments, and the role of state-owned enterprises in restructuring energy systems. Part 3 turns to niches and innovation, showcasing cases from Africa, Asia, and Latin America on ocean energy, local innovation ecosystems, and decentralized renewable solutions, and distilling lessons on how they scale and transform broader regimes. Throughout, the book foregrounds questions of justice, equity, and community agency, emphasizing that successful energy transitions require inclusive governance as well as technological change. It speaks to policymakers, practitioners, and scholars seeking rigorous analysis and practical guidance on how developing countries can become leaders in the global shift to a low-carbon future.