Renewable Energy Integration: Challenges and Solutions for Grid Stability in India's 500 GW Non-Fossil Future

India has achieved a significant milestone by attaining 50% of its cumulative electric power installed capacity from non-fossil fuel sources in June 2025, five years ahead of its 2030 target. This paper examines the critical challenges and innovative solutions for integrating renewable energy sources into the Indian power grid, focusing on the transition from capacity expansion to system integration and grid stability. With total renewable energy capacity reaching 253.96 GW as of November 2025, the country faces substantial technical and infrastructural challenges in maintaining grid stability while accommodating variable renewable generation. The paper analyzes key challenges including intermittency, transmission connectivity issues, and grid curtailments, while presenting comprehensive solutions such as Battery Energy Storage Systems (BESS), smart grid technologies, and hybrid project configurations. The analysis reveals that BESS has emerged as a critical enabler with over 20 GWh of standalone projects awarded since April 2024, while advanced technologies including smart inverters, AI-based forecasting, and Vehicle-to-Grid (V2G) systems offer promising solutions for grid management. The paper concludes with policy recommendations and future outlook for achieving the 500 GW non-fossil energy target by 2030, emphasizing the need for continued investment in storage technologies, grid modernization, and supportive regulatory frameworks.