Research Progress on Solar Energy Storage and Conversion Technologies for Sustainable Development: Prospects, Challenges, and Future Outlooks

Solar energy is inherently intermittent, and as demand grows for dependable low‐carbon power, efficient storage is essential to the sustainable energy transition and long‐term energy security. Yet most reviews examine these technologies in isolation rather than comparing them directly. This study compares six leading routes for storing solar energy: sensible heat, latent heat, thermochemical, electrochemical, supercapacitor, and large‐scale mechanical systems. Each is assessed within a single framework spanning thermodynamic performance, storage density, operating temperature, efficiency, commercial readiness, and application suitability. The thermal technologies differ markedly. Sensible heat storage reaches efficiencies of 50%–90% but has low storage density (~0.18 GJ m −3 ), latent heat storage holds nearly 2.5 times more energy than a conventional water tank (150–200 kJ kg −1 ), and thermochemical storage achieves the highest density (~1.8 GJ m −3 ) with very low standby losses, making it suitable for seasonal use. Among nonthermal options, lithium‐ion batteries deliver 85%–95% round‐trip efficiency, supercapacitors exceed 90% over 30,000 cycles, and pumped hydro sustains 70%–85% at grid scale. Overall, hybrid systems integrating thermal, electrochemical, hydrogen, and mechanical pathways offer the most promising route to dispatchable renewable power.