Optimal demand controls for a heat pump water heater under different objective functions

High penetration of variable sources of renewable power generation, such as photovoltaic (PV) systems will lead to supply-demand imbalances in the entire power system. Activation of residential power usage, storage, and generation by sophisticated scheduling and control using a home energy management system (HEMS) will be needed to balance power supply and demand in the near future. In this study, we improved a part of our optimum operation-scheduling model relevant to the operation of a heat pump water heater (HPWH). Using this new model, the optimal demand controls of an HPWH were analyzed with four types of objective functions. It was found that the most economical operation schedule using current electricity rates was not the same as schedules utilizing other objective functions. These results showed that we need to harmonize the objectives of demand control with incentive rewards for consumers in the future.