Large scale renewables raise new challenges and provide new opportunities across electricity systems. This paper considers the barriers faced by large scale renewables in electricity systems in Sub-Saharan Africa and South Asia. We review the current state of knowledge in relation to grid-connected renewables. This paper then explores key issues in electricity system structure, the main challenges to the uptake of renewables, and the various existing fiscal and policy approaches to encouraging renewables. We also highlight possible ways moving forward to ensure more widespread renewables deployment.