MPPT and Energy Storage Control of a Hybrid PV Array and Heat Pump System: An Experimental Research

Due to the increasing concerns on the environmental and climate changes, photovoltaic (PV) array hybrid heat pump system is promising in the future residential buildings. However, the maximum power point tracking (MPPT) for the PV array integrated with the heat pump is challenging because of the device coupling and the necessity of energy storage. To this end, this paper firstly formulates the problems by analyzing the operational requirements. Secondly, a hybrid feedforward and feedback control structure is developed to fulfill the MPPT objective based on the “perturb and observe” method. To mitigate the power fluctuation caused by the MPPT operation of PV, a water tank is used to store the excessive energy and release to make up for the energy deficit. The system is identified as a transfer function model based on a step response, based on which a PI controller is designed. The simulation results agree well with the experimental results and thus confirm the feasibility of the proposed method. The MPPT function can be realized while the indoor temperature is kept constant, which provides solid foundation for the future promotion of the proposed method.