Solar photovoltaics and hydrogen energy as pathways to a sustainable future

The transition to low-carbon energy systems requires technologies that provide renewable electricity, flexible energy storage, and pathways for decarbonizing hard-to-electrify sectors. This review critically compares solar photovoltaic (PV) and hydrogen-energy technologies within an integrated system-level framework, considering technological maturity, efficiency, economics, environmental impacts, infrastructure, applications, and future prospects. Solar PV offers mature, modular, and increasingly cost-effective electricity generation, but its variability, land and material requirements, degradation, and end-of-life management remain important challenges. Hydrogen provides complementary value as an energy carrier, industrial feedstock, and long-duration storage medium, although its production and use involve additional energy losses and costs. The review indicates that direct PV electricity is generally preferable when feasible, batteries are well suited to short-duration storage, and hydrogen is more advantageous for long-duration storage and hard-to-electrify applications. Overall, PV and hydrogen should be considered complementary components of an integrated low-carbon energy system.