Approximately 1.2 billion people will need to gain access to electricity to achieve universal access by 2030. The only way to achieve this is through a combination of the main grid extension, mini grids, and off-grid solar. This report shows that about half a billion people can be cost-effectively provided with electricity through mini grids. The combination of falling costs, dramatic increase in the quality of service, and favorable enabling environments have made modern mini grids a scalable option to complement grid extension and solar home systems. The report takes stock of the global mini grid market and industry; analyzes in detail the solar-hybrid mini grid costs and technological innovations; shows the importance of introducing income-generating machinery and micro-finance early in the planning process; and provides policy makers, investors and developers with insights on how mini grids can be scaled up.