Pit thermal energy storage systems are artificial pools in which a large pit is sealed off from the soil, insulated, filled with water, and given a floating cover. The water can be heated by various heat sources, for example solar collectors or waste heat. Heat storage — storing solar energy directly as thermal mass rather than converting it to electricity and back — is 5 to 10 times cheaper per kWh of storage capacity than battery storage, lasts indefinitely, and requires no electronics, BMS, or inverter., Swimming Pool. This review highlights the latest advancements in thermal energy storage systems for renewable energy, examining key technological breakthroughs in phase change materials (PCMs), sensible thermal storage, and hybrid storage systems. Practical applications in managing solar and wind energy in. Thermal storage plays a crucial role in solar systems as it bridges the gap between resource availability and energy demand, thereby enhancing the economic viability of the system and ensuring energy continuity during periods of usage. These include the two-tank direct system, two-tank indirect system, and single-tank thermocline system.