## 5 Methodological Review of Existing Literature  
A main aim of this study is to carry out a chronological analysis of review articles related to the incorporation of EVs in distribution networks and the integration of Renewable Energy Sources (RES) and management of these systems over time. Review articles include a summary of the most important advances at the time they were written; a meta-analysis of these will enable us to understand the evolution of technological research on the subject we are dealing with and make extrapolations for the future. To conduct the study, we worked with the IEEE Xplore, Scopus, Google Scholar, and Web of Science databases, planning different levels of searches. In the first place, the search period was determined, finding 1973 as the first year in which an EV article was published within what we consider the modern era, as opposed to the historical context discussed in Section 2. An iterative searching process was carried out including more terms and conditions, revealing a few articles containing the characteristics that we sought. In a first analysis (Figure 11), we evaluated the literary production containing \"electric vehicle and electrical networks\" terms, along with their possible variations in the search rules, for any type of scientific article, finding the first references in 1976 (series in blue). A part of this methodology is based on [104]. The next analysis added the \"renewables\" term to the previous search, obtaining the yellow series. Regarding the blue series, two periods were detected: the first up to 2007, with scant scientific output, and another from 2007 onwards showing continuously growth until 2022. Looking at the chart carefully, as many as eight different trend changes can be observed:  
**1973-1975**: There are no scientific 'EV' plus 'electrical networks' publications. **1976-1990**: Small EV models were introduced into the market, with limited benefits because they used lead-acid batteries with low charge density. In this period, the effects on the power factor of the first EV chargers, which generated harmonics in the distribution network, began to be investigated [105]. **1991-1996**: These were the years in which the GM EV1 was launched and the use of Ni-MH batteries with higher capacities and charge cycles became more widespread. There was interest studying the issue of charging peaks when many EVs were present in  
Figure 10: Number of electric truck sales per year and region. distribution networks, with some authors concluding that EV penetration greater than 20% could not be achieved due to the long battery charging time of 12 h [106]. **1997-2005**: The launch and worldwide distribution of the Toyota Prius meant that Hybrid Electric Vehicles (HEV) began to take center stage. The study of BEVs and their impact on networks continued to advance, seeking to determine the impacts of different levels of EV penetration [107] and fast chargers [108] as well as how transformers are affected by EVs [109]. **2006-2010**: Fuel price increases and the launch of the Li-ion battery Toyota Roaster BEV boosted the interest of researchers in EVs. The Vehicle-to-Grid (V2G) paradigm was defined for the first time [110], which triggered profuse research on this subject. By the end of this period, almost all of the \"classic\" EV problems had been described. **2011-2016**: BEVs along with hydrogen combustion engines and fuel cells, were considered a real solution for gradually replacing fossil fuel-powered combustion engines. Studies carried out at this point included \"classic\" EV problems, optimization of recharging [111], cancellation of harmonics, and potential positive effects of EVs on the network [112]. **2017-2020**: Topics related to network voltage stability through the automatic variation of battery charge current level were researched [113] as well as the effects on EV generation and consumption in real time [114].