Sehba Anjum Mumtaz Ahmed, Penumaka Nagababu, Sadhana Rayalu
The accelerating global push toward clean energy has sparked significant interest in solar-powered electrochemical methods for producing green hydrogen. This review evaluates three prominent technologies: photovoltaic (PV)-electrolysis, concentrated solar power (CSP)-electrolysis, and photoelectrochemical (PEC) water splitting. While all utilize solar energy to drive hydrogen generation, they differ notably in operational principles, efficiency, cost, and technology readiness. PV-based systems are the most mature and commercially deployed, offering modularity and high reliability. However, they depend on costly electrolyzers and are limited by the intermittent nature of solar radiation. CSP-integrated systems, particularly those coupled with high-temperature electrolysis, such as solid oxide electrolyzer cells (SOECs), offer potential for improved efficiency and energy integration. Yet, their adoption is hindered by high capital costs and operational complexity. PEC systems, though still at a nascent stage, offer a compact design and direct solar-to-hydrogen conversion, but face significant obstacles, including low solar-to-hydrogen (STH) efficiency, material degradation, and scalability issues. This review further examines techno-economic aspects such as the LCOH, system performance metrics and the main challenges impeding widespread implementation. Emerging strategies such as advanced materials, nanostructured photoelectrodes and tandem architectures are highlighted as key pathways to enhance system efficiency and reduce costs. Overall, this review provides a comparative assessment and outlines future directions for advancing solar-based hydrogen technologies toward large-scale, sustainable deployment.