This report from the Energy Storage Partnership, prepared by ESMAP with contributions from ARE, RSE, Loughborough University, and the IADB, examines the status and projections of battery deployment for mini grids in developing countries. The Energy Storage Partnership is a global partnership convened by the World Bank Group to develop sustainable energy storage solutions for these countries. ESMAP is a partnership between the World Bank and 24 partners that provides analytical and advisory services to help low- and middle-income countries reduce poverty and boost growth through sustainable energy solutions. The report is available at https://www.esmap.org/the-energy-storage-partnership-esp.