Silicon-based composites (SBC) are gaining popularity as sophisticated materials for renewable energy systems that operate under harsh mechanical, thermal, and environmental conditions. This research presents a critical and comparative evaluation of SBC for wind and hydropower applications by combining quantitative performance data, component-level viability, and industrialization problems such as scalability and cost considerations. Reinforcement topologies ranging from particle and short fibers to continuous, along with essential processing techniques such as chemical vapor infiltration, melt infiltration, polymer infiltration and pyrolysis, and new additives. The fundamental mechanical, thermal, tribological, and chemical durability qualities are examined in terms of the predominant deformation, damage, and degradation mechanisms. The performance of SBC under actual service conditions—such as cyclic loading, erosion-corrosion, cavitation, and harsh environments—is examined and compared to traditional glass- and carbon-fiber-reinforced polymer composites. Aside from technical features, the review is unusual in that it includes industrialization and commercialization views, identifying scale-up impediments, quality control issues, and technology-market misalignments that prevent acceptance. To connect material-level advantages with system-level benefits, business model archetypes and risk-sharing techniques are thoroughly evaluated. This study frames silicon-based composites as high-performance materials for next-generation wind and hydroelectric infrastructure, as well as strategic directions for accelerating their industrial application.