This research explores key aspects of Generation Expansion Planning (GEP) for renewable energy sources, focusing on the integration of solar and wind power into the existing power grid. The study addresses significant challenges such as reducing dependency on fossil fuels, mitigating environmental impact, and enhancing grid resilience and reliability. Given the variable nature of renewable energy sources, the research emphasizes the importance of precise modeling and analysis. The findings highlight the integration of solar and wind farms into the grid, forming a basis for effective generation planning. Additionally, an uncertainty analysis utilizing the Weibull distribution accounts for fluctuations in wind speed and solar irradiance, ensuring more accurate and reliable modeling of renewable energy generation. A comprehensive reliability evaluation using reliability indices assesses the impact of renewable energy sources, both individually and collectively, on the grid. This evaluation plays a crucial role in understanding the effects of renewable integration on overall grid reliability and informs the development of robust GEP strategies. These insights contribute to advancing renewable energy integration into power systems, promoting sustainable and resilient grid operations.