A smart algorithm to optimally manage the charging strategy of the Home to Vehicle (H2V) and Vehicle to Home (V2H) technologies in an off-grid home powered by renewable sources

Abstract

European directives promote activities aimed at developing a sustainable and decarbonised energy system, with a greater share of electricity production from renewable sources, within a framework of greater efficiency. In the energy of nZEB buildings, the reduction of energy needs is accompanied by the use of hybrid renewable energy systems (HRES) for the production of energy on-site to be used for appliances and lighting and also for mobility through the electric vehicle (EV) charging. With reference to this framework, the paper studied the integration of Vehicle to Home (V2H) technology in HRES for residential users. The HRES consists of a photovoltaic (PV) generator, a wind generator, an electrical storage system and a charging station for an EV, in a stand-alone context. V2H technology provides for the use of the EV as an emergency energy source if the generation and storage systems are unable to guarantee the satisfaction of the residential load. For this purpose, an algorithm is proposed that can manage and optimize the dissipated energy produced in excess, providing that this is sent, when possible, to the EV for extra charging compared to the residential charging expected in the load determination. This extra charging process does not affect the load required by the residential user being carried out directly by the generation system with the excess energy produced. With reference to an isolated single-family user not connected to the network and to the use of an EV (which ensures mobility), two energy scenarios were considered, in the absence and the presence of V2H technology. The possibility of EV charging at night and an additional extra charge during the day were considered. The load required for nocturnal EV charging rests on the residential load of the home, while the extra charge is directly borne by the generation system. To reduce excess energy, which in the considered context must be dissipated, two charging strategies were considered that differ in the choice of whether or not to carry out nocturnal charging depending on the EV state of charge. The different system configurations and use of the generated energy make the energy analysis complete to identify the performance of these systems. The dynamic simulations of the HRES operation were carried out through TRNSYS, for the dynamic simulation of the PV and wind systems, which is coupled with MATLAB to dynamically simulate the residential battery and the H2V and V2H technologies. Starting from the hourly results obtained, an yearly energy analysis was carried out.