This paper covers all core concepts of ESSs, including its evolution, elaborate classification, their comparison, the current scenario, applications, business models, environmental impacts, policies, barriers and probable solutions, and future prospects. . Surplus energy obtained from RESs can be stored in several ways, and later utilized during periods of intermittencies or shortages. The idea of storing excess energy is not new, and numerous researches have been conducted to adorn this idea with innovations and improvements. This review is a humble. . Electrochemical storage systems like lithium-ion batteries are suitable for short-term applications, offering high energy density and efficiency—but they remain costly, pose safety risks, and have significant environmental impacts. Thermal storage systems such as the ThermalBattery™ offer a robust. . In this study, we address the technological feasibility of intermittent renewable energy generation systems, focusing on storage solutions for PVS energy. We propose a framework according to one of the essential parameters for their application in PVS: Energy Density or Specific Energy (Wh/kg).
