Effective energy policies rely on credible and comprehensive national energy data systems, in developed and developing economies alike.  Smart system technologies will play a central role in the clean energy transition—including applications in smart homes, factories, transport systems, and renewable electricity grids—and their ability to compile and communicate point-of-use energy data presents new opportunities for improving national energy data systems.  This paper reviews the growing importance of energy data systems for energy policy in the developing country context, identifies key characteristics a national data system needs to have in order to be robust and viable, discusses the potential role of smart system technologies in national energy data systems moving forward, and recommends several future research areas to better understand their potential, and in developing countries in particular.