This two-volume set CCIS 2612-2613 constitutes the refereed proceedings of the Second International Conference on Renewable Energy, Green Computing, and Sustainable Development, REGS 2025, held in Hyderabad, India, during February 21-22, 2025. The 54 full papers were carefully reviewed and selected from 351 submissions. REGS 2025 is an interdisciplinary conference that aims at diverse fields of engineering and technology with a focus on smart and energy efficient computing, green technology and sustainable systems design and development, ranging from theoretical developments to industrial problems.