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This paper investigates the use of common thermal storage systems for demand side management in off-grid situations for nearly zero energy buildings. Typical parameters and characteristics were analyzed to develop mathematical models for freezers, water heaters and space heating/cooling. The models used in this work are based on simplified equations derived from differential equations. Simplified models of a battery storage and a PV-system have been added. Models for the thermal storages, PV-system and battery storage were merged to one system model. All models and simulations were designed and conducted with Matlab. Various pre-defined price based set point calculation algorithms were modified to work with the off-grid system based on the system’s voltage and available PV-power. Voltage and battery’s state of charge based algorithms are developed in this work. In a system with a freezer, water heater and space heating/cooling that is powered by a PV-system only, a possible battery storage capacity reduction of up to 50% with PV-power based and up to 36% with SOC based algorithms compared to the same system with fixed set point thermostatic control could be achieved. Additionally, the capacity could even be reduced by up to 18% by solely reacting to voltage drops.