This book constitutes the refereed post proceedings of the First International Conference on  Renewable Energy, Green Computing, and Sustainable Development, REGS 2023, held in Hyderabad, India, during December 22-23, 2023. The 15 full papers included in this book were carefully reviewed and selected from 133 submissions. They were organized in topical sections as follows: Expert Systems and Artificial Intelligence; Modelling and Methods of Green Computing; Power Electronics and Renewable Energy Technologies and Communications and Signal Processing.