Recent advances in lithium-ion battery technology and rapidly falling prices have ushered in an era of unprecedented growth in utility-scale energy storage projects. Propelled by ample government incentives, markets around the world have seen a swift rise in the number and size of battery energy storage systems (BESS) connected to the power grid. This expansion has spurred massive advancements and interest in the design, construction, finance, and operation of these plants. The BESS Book is intended for the reader who is interested in learning about the fundamentals of lithium-ion battery systems. All key concepts of BESS technology, engineering, finance, construction, and operation and maintenance (O&M) are covered, as is hands-on learning from the field. Later chapters discuss battery controls, finance, development, and safety. The final section presents an outlook on the future of energy storage technology, and how anyone can start or advance a career in the battery industry. The book features examples from actual projects, market trends, lists of leading firms, photographs, and original graphics throughout. The content has been written in a way to help present ideas clearly for newcomers to the field, while including comprehensive technical content for energy storage professionals. The authors have over 5 GWh of combined energy storage project experience, including work with some of the largest projects and leading names in energy storage development and finance. Their hands-on experience combines theory with practice to give a clear picture of the current state of the industry, where it is going, and how the reader can get involved. Dive into this comprehensive guide to: Discover the fundamental principles of lithium-ion BESS technology, engineering, and finance Explore the latest advancements, safety protocols, policy shifts, and market trends driving the global expansion of large battery systems Gain invaluable hands-on insights from real-world projects, from design and construction to operations and maintenance With vivid examples, detailed graphics, and expert knowledge, this book provides a thorough overview of the booming energy storage industry. Whether you're looking to advance your career, become a BESS developer, or stay current on the latest trends, The BESS Book is a gateway to knowledge of a clean energy future.