This report examines the challenge of bringing power to over one billion people who live without electricity, mostly in remote, rural areas in sub-Saharan Africa and South Asia. Under a business-as-usual scenario, almost 700 million people will still be without access to electricity in 2030, mostly in sub-Saharan Africa. That is equivalent to double the population of the UK and the US combined. This research demonstrates that off-grid renewable electricity, particularly solar, can offer a wider range of modern solutions for enhancing access to energy in rural areas. Solutions include solar lamps and stand-alone solar panels that are often cheaper, faster, more reliable, safer and cleaner than extending a centralised grid, or using kerosene and diesel. Drawing on five case studies from the Democratic Republic of the Congo, Nepal, Nigeria, Myanmar and Tanzania, the report assesses the political challenges of scaling-up off-grid renewable energy and gives a set of key policy recommendations for overcoming these barriers. The research also shows that off-grid renewable electricity can contribute to transforming lives by improving health, education, gender equality, income generation and environmental sustainability.