<p>Solar fuel technologies use sunlight to synthesize value-added molecules that can be used as renewable fuels or chemical feedstock. They share the common principle of converting and storing solar and other renewable energy in chemical bonds, but differ in the harvesting mechanisms, catalytic processes and systems used. These distinctions lead to different advantages, challenges, maturity and deployability prospects. In this Perspective, we provide a cross-disciplinary view of five major solar fuel platforms — photocatalysis, photovoltaic-driven electrolysis (PV + EC), photoelectrochemical, photothermal and plasmonic catalysis — to identify transferable insights and design principles. The wide span of solar-to-hydrogen efficiency (typically 0.1–15%) and levelized cost of hydrogen (US$2–30 kg⁻¹ H₂) depending on the system reflect both mechanistic limitations and system-level constraints that keep performance below theoretical limits. Common bottlenecks emerge, including spectral mismatch, charge-management and heat-management losses, stability in harsh operating environments and dependence on critical materials. At the same time, shared design principles — such as defect and facet engineering, multi-absorber architectures, plasmonic and photothermal enhancement, interface stabilization and catalyst–reactor co-design — offer transferable strategies capable of improving performance across platforms. Together, these insights provide a transversal unifying vision on how advances in one solar fuel technology can accelerate progress in others and inform pathways towards scalable, efficient and economically viable solar fuel production.</p>