Developments and Barriers in Solar Energy: Conversion Technologies, System Integration, and Future Directions

Abstract

Solar energy is central to the global shift toward sustainable power systems. Owing to its vast availability, scalability, and diverse technology base, it is the leading renewable option to address climate-mitigation and energy-security goals. This review synthesizes recent progress in solar harvesting across photovoltaic (PV) devices, concentrated solar power (CSP), photothermal platforms, solar-driven hydrogen production, and hybrid solar–storage configurations. It covers materials breakthroughs—perovskites, tandem architectures, and nanostructured absorbers—as well as system-level advances in grid integration, demand-response coupling, and smart solar design. Using a comparative framework, we assess efficiency gains, cost declines, life-cycle sustainability, and techno-economic performance across pathways. Key findings include >85% PV cost reductions since 2010, CSP achieving dispatchable output via molten-salt thermal storage, and emerging solar-to-hydrogen routes surpassing 15% efficiency at lab scale. Figures and tables map trends in deployment, record efficiencies, and integration bottlenecks. The discussion highlights remaining barriers—intermittency, land-use trade-offs, end-of-life module recycling, and region-specific socio-economic factors. We conclude that no single pathway is universally optimal; a diversified portfolio that blends PV, CSP, storage, and solar fuels offers the most resilient trajectory to net-zero systems. Future work should focus on durability, circular-economy strategies, and policy mechanisms that accelerate widespread solar integration