## 1 Introduction  
The unusual increase of technological applications in everyday life inevitably corresponds to an enormous increment of energy consumption. The energizing of the continuously increasing electric vehicle (EV) fleet can prove detrimental for the already-established electric grid, which seems overloaded by the growing human needs. Electrification of vehicles is currently recognized as a feasible option towards an environmental-friendly coverage of these needs, although the automobiles' supply must be independent from the weather and the availability of the grid, if it belongs to the EV fleet. Nowadays, the current energy needs cannot be satisfied by fossil fuels due to strict environmental limitations, mainly for CO\({}_{2}\) emissions and other greenhouse gases, as defined by the Kyoto Protocol, Paris Agreement, and several other policy guides/agreements. This trend obviously affects transportation as well and, precisely, the design and implementation of passenger cars. During the last few years, electrified vehicles flood the market while many technological options aspects and relative technologies have been proposed. Currently, the marketed electric vehicles are classified into two main groups: the all-electric vehicles (AEVs) and the hybrid electric vehicles (HEVs). The latter combine an internal combustion engine with an electric motor to eliminate the CO\({}_{2}\) emissions [1]. Several reports indicate the penetration of EVs in the automotive market: from a couple of hundred electric vehicles (EVs) in 2010, nowadays the existing EV fleet approaches 6 million, which means an increase of 6000% [2]. Furthermore, market models predicted approximately 100 million EVs on the road by 2030, while this is expected to raise to about 550 million by 2040 [3, 4]. Although the above scenario for the future of the automotive market sounds like a very suitable option for addressing environmental issues, there are some major concerns regarding the primary source for electricity supply. Several published works have already underlined that the electrification of the fleet will not drastically improve the planet's situation if electricity is produced by conventional fossil fuels. Therefore, the extensive use of EVs corresponds to increased needs for electric power, which would have a significant environmental impact. Under this perspective, the increasing demand for electric power must inevitably be covered by renewables and other environment-friendly power sources in order to significantly eliminate CO\({}_{2}\) emissions. Specifically, it has been proposed that an EV can be transformed into a reasonable solution to reduce environmental pollution only by using renewable electricity and decreasing CO\({}_{2}\) emissions up to 2000% [5]. Here it must be mentioned that integrating millions of EVs into the grid of the social electric network can impact the load profile and generally its operational characteristics such as phase, voltage, and frequency [6, 7]. Moreover, this can cause power losses, stability issues, and overloading of several grid components [8, 9]. On the other hand, off-grid systems for electric power supply present some negative environmental effects and/or ineffectiveness from a financial point of view [10, 11]. Some drawbacks are revealed from the biogas-photovoltaic project implemented in Uttarakhand state in India, where the overall emissions were observed to be elevated [12]. In China, several studies have shown that if there is no combination between the primary, secondary, and tertiary industries, then an off-grid system is not viable [13]. Also, in a survey conducted in a rural area of Bangladesh, the unit cost of electricity from optimal off-grid power supply was much higher than that from the grid [14]. Moreover, standalone hybrid applications used for the electrification of EVs simultaneously use more than one Renewable Energy Source (RES) technology under a complex multiparametric system, which requires a large installation space, being therefore inappropriate for urban networking.