Cross-sector barriers and integrated solution pathways for solar, wind and hydropower energy systems

Large-scale deployment of renewable energy systems is central to global decarbonisation strategies, yet integration at high penetration levels remains constrained by interacting technical, economic, infrastructural, and socio-regulatory barriers. Existing review studies typically examine these challenges in isolation or within single-technology silos, limiting system-level prioritisation across renewable technologies. This study presents a semi-systematic integrative review of recent literature (2020–2025) to develop a unified classification framework that links integration barriers with corresponding solution pathways across solar, wind, and hydropower systems. The proposed framework explicitly captures interactions between technical constraints (e.g., intermittency, grid stability, power quality), economic limitations (e.g., capital intensity, financing risk, market design), transportation and storage bottlenecks, and social–regulatory factors. A comparative severity-weighted heat-map is introduced to assess the relative impact of these barriers across technologies, enabling cross-sector prioritisation rather than technology-specific diagnosis. The review synthesises system-level solution pathways, including hybrid renewable configurations, sector-coupled integrated energy systems, advanced storage portfolios, Power-to-X routes, and green hydrogen as a long-duration flexibility vector. Techno-economic optimisation tools such as HOMER are critically assessed as screening-level instruments for hybrid system design, with explicit discussion of their applicability limits under high-renewable, network-constrained conditions. The findings suggest that effective renewable integration is increasingly dependent on the coordinated deployment of flexibility, cross-sector coupling, and coherent policy and market frameworks, rather than incremental technology-specific improvements. By aligning barrier severity with solution pathways across multiple renewable technologies, this review provides practical guidance for policymakers, system planners, and industry stakeholders seeking reliable and cost-effective pathways toward net-zero energy systems.