Book excerpt: TRaditionally, mini grids have been viewed as “off-grid†? systems that are built and operated solely for communities without electricity. The reality, however, is that millions of people in Sub-Saharan Africa and India who are connected to the main grid suffer from poor grid reliability (“weak grid†?), sometimes with a power supply of less than 4 to 8 hours daily and with frequent disputes over the accuracy of billing. As a backstop, these poorly served customers often find themselves forced to rely on small fossil fuel†“powered generators that are noisy, polluting, and expensive to operate. Mini Grid Solutions for Underserved Customers: New Insights from Nigeria and India explores another option: undergrid mini grids. These are mostly solar hybrid†“powered mini grids built and operated by private companies in areas already connected with the main electricity grid but facing poor technical and commercial service. This comprehensive book examines how undergrid mini grids can create win-win-win outcomes for retail customers, distribution enterprises, and mini grid developers. Drawing on extensive discussions with pioneering developers, the book showcases detailed case studies from Nigeria and India, shedding light on the challenges and opportunities of interconnected and non-interconnected undergrid mini grids. The authors address technical issues of grid interconnection and delve into the policy and regulatory considerations crucial for the financial sustainability and success of undergrid mini grids. The book is an invaluable resource for policy makers, energy practitioners, and researchers seeking practical insights to bridge the electricity access gap, empower communities with reliable and affordable electricity, and drive environmentally and commercially sustainable development. • “The report is rich with insight, not least because the authors have been able to contrast the Nigeria and India approaches taken by the respective private sectors in each country. The five case studies are very valuable. The authors have powerfully illustrated the importance of the policy and regulatory framework and how that translates into investor behavior.†? — Mohua Mukherjee, Senior Research Fellow, Oxford Institute of Energy Studies • “This great report represents a pivotal turning point in the history of energy and has global implications for the role of mini grids for communities that have been poorly served by main grid utilities.†? — Peter Lilienthal, Founder HOMER Energy • “This is a tremendous addition to the literature on mini grids and an important guide for all of us practitioners working in this area.†? — James Sherwood, Director of Research & Innovation, RMI | Global South Program • “This refreshingly honest and open report provides an excellent overview of interconnected and isolated mini grids, as well as a thorough analysis of key ground-level implementation issues in regulation, business, and engineering.†? — Joanis Holzigel, Chief Operating Officer, INENSUS