A solar-assisted heat storage device, including at least one molecular sieve heat storage bed and a heat storage water tank. The molecular sieve heat storage bed includes a cylindrical housing and a plurality of heat storage pipes disposed in the housing. The heat storage pipe includes metal pipes having meshes and an adsorbent layer adhered to the surface of the metal pipes. The adsorbent layer includes a molecular sieve adsorbent material adapted to match with water to form a working pair for heat exchange. Two ends of the housing are both configured with sealing valves and respectively connected to an air inlet and an air outlet of an air preheater. One end of the housing is configured with a water inlet connecting to a water outlet of the heat storage water tank, and the other end of the housing is configured with a water outlet.

One or more embodiments relates to a hot water storage system and a method for storing hot water, the system including at least one oversized diameter tube and at least one plumbing line diameter tube coupled to and in fluid communication with at least the at least one oversized diameter tube. The at least one oversized diameter tube is further coupled to and in fluid communication with a building hot water source.

A fluid-based system for use in heating and/or cooling. In particular, the system may have a fluid heating device, which may be a solar fluid heating device, configured to heat a fluid. Heat from the heated fluid may be transferred to one or more cooling subsystems or heating subsystems. A cooling subsystem may be an absorption cooling subsystem, for example, wherein heat may cause phase change of a refrigerant. A heating subsystem may include a storage tank through which heated fluid may be circulated to heat the storage tank. A system of the present disclosure may include multiple cooling and/or heating subsystems for cooling and or heating a variety of different environments, objects, or materials.