###### Abstract
In [9], three different systems were investigated for a single family house through one year simulation by Trnsys(r) software: a dual source (air and PVT) heat pump integrated with two storage tanks to directly store the hot water for domestic hot water (DHW) if the water temperature reached the set point or to send it to the cold storage to act as heat source; an air-water heat pump integrated with standard photovoltaic panels; and an air-water heat pump integrated with hybrid PVT panels for DHW production only. Multisource is an extension of dual source, when more than two heat sources are used by the heat pump. In [10], an integrated heat pump system utilizing a geothermal field, solar energy, and drain water heat recovery was empirically studied. The continuous monitoring of the real COP of the space heating plant allowed useful adjustments of the control system to enhance the efficiency to be proposed. [PERSON] et al. [11] developed a model of a multisource and multi-energy plant in the Matlab(r) environment. The goal of their study was the optimization of the size of the different technologies by using a genetic algorithm, with the goal of minimizing the primary energy consumption in different climatic zones. Different combinations of a PVT collector and a multisource (air, solar, and ground) heat pump for space heating and DHW production of a single-family house located northeast of Italy were investigated by [PERSON](r) in [12]. A dedicated mathematical model based on the equivalent electrical circuit was developed by the authors for the estimation of the electrical and thermal performances of PVT. An appreciable increase of energy efficiency between 14% and 26% compared to a standard air-to-water heat pump system was reported. [PERSON] et al. [13] studied a multisource hybrid heat pump system with seasonal thermal storage utilizing solar, geothermal, and air energy. By optimizing the transition conditions of the different operating modes, the average COP of the system with seasonal thermal storage was 3.06, which allows a simple payback period of the multisource heat pump of 4 years. In contrast to the previous studies, recently the authors studied a configuration with the coupling of evacuated tube collectors and PVT modules to drive an absorption heat pump-based plant [14]. By means of dynamic simulations, the optimal sizing of the storage tanks, of the ground heat exchanger, and of the two solar fields in two different climates was developed. As a matter of fact, there is a complexity both in the design phase and in the controlling because such systems include many different appliances. To the authors' best knowledge, very few works have focused on the optimization of the control strategy. For example, [PERSON] et al. [15] identified more than 10% difference of heating energy usage of a water-to-water heat pump system integrated with solar thermal collectors, vertical boreholes, and horizontal underground loop by comparing two different control strategies. More recently, [PERSON] et al. [16] studied the thermal and electrical behavior of a water-to-water heat pump system facing heating, cooling, and DHW loads, supplied by two thermal reservoirs connected to a solar loop (composed either of solar thermal collectors or PVT collectors) and to a ground loop. The authors described the control strategy to vary the set-point temperatures to simulate different management choices and operating conditions. Recently, a review of the solar-assisted heat pump technology identified the multi-source heat pump and its control logic as one of the key technological challenges for the present and the future of this technology [17]. In this paper, the authors reported on two case studies in which they were involved in the recent past, where the dynamic simulation was a useful tool to design the multisource heat pump system and its control logic with the aim of the best energy performance in terms of minimization of the non-renewable primary energy consumption.