This book explores the realm of efficient energy harvesting through passive approaches for thermal collectors. With the increasing demand for sustainable and renewable energy sources, passive thermal collectors have emerged as a promising avenue for energy conversion. By harnessing ambient heat and converting it into usable energy, these systems offer a viable solution for meeting our energy needs while minimizing environmental impact. The abstract introduces the core concepts covered in the book, highlighting the focus on efficient energy harvesting through passive approaches for thermal collectors. It emphasizes the significance of these systems in addressing the global energy challenge and the potential they hold for a sustainable future. Readers will delve into the fundamental principles behind passive thermal collectors and their various applications throughout the book. The authors explore innovative techniques, advanced materials, and cutting-edge technologies that maximize energy conversion efficiency. This book provides a comprehensive guide and a valuable resource for researchers, engineers, and enthusiasts seeking to understand and contribute to this rapidly evolving field. By adopting efficient energy harvesting through passive thermal collectors, we can tap into abundant and renewable energy sources, reduce our dependence on fossil fuels, and mitigate climate change. This book offers insights, knowledge, and inspiration to pave the way for a greener, more sustainable energy future.