## 5 Discussion of the Results  
The analysis of the results obtained makes it possible to formulate two conclusions related to the consequences that the high penetration of electric cars and the measures taken to mitigate their effects can have on the distribution system. The transformers analysed are able to withstand the additional loads represented by electric vehicles, even if especially in the evening hours, they are forced to work in overload. The implementation of photovoltaic systems, in the specific cases analysed, had no significant consequences as regards the effects on voltage. However, in older networks and especially in nodes near the distribution stations, high photovoltaic production can contribute to a voltage rise of more than 10% compared to the nominal value. On the other hand, the strong penetration of EV into the farthest nodes, can generate the opposite effect, causing a strong drop in voltage. Keeping the hypothesis of an uncontrolled recharge, the positive and negative impacts of EV and PV systems are balanced with major effects from one or the other depending on the level of penetration. Due to the non-coincidence between the EV recharge time interval and the PV production period, the effectiveness of mitigation is relatively weak; therefore, the implementation of an accumulation system is an ideal solution. The voltage profile has presented a strong dependence on the demand. The voltage drop is stronger as the distance from the primary  
Figure 18: **(a)** Power requested from the fast charging station and **(b)** voltage profile along the medium voltage (MV) feeder. station increases, even if the feeder length has less influence on the voltage drop, if there is not such a high current. It is also important to remark that there some voltage profiles are not affected in those hours when the generation is zero or almost zero. The quasi-dynamic load flow of one day has shown this trend. Another important element that influenced strongly the voltage profile is the power injected by a generator. The generator node suffers a strong voltage increase according to the power injected and the line reactance. It is important to underline that reactive power injection or withdrawn can have a positive effect on the voltage, which can be decreased, by absorbing a certain amount of reactive power (inductive behaviour) or increased injecting reactive power (capacitive behaviour). From the simulations performed, it is possible to confirm that thermal limits affect mainly the buses near to the primary substations. In fact, the first nodes are crossed by a large amount of power, which needs to flow toward the farthest LV users. In addition, a share of the new power injected by DG can flow upstream to the MV busbar. If more load is connected in the same bus where the DG is being connected, the hosting capacity can increase, because the generation can be absorbed by the local load, and there is no need to transport the power through the lines. The ampacity of lines represents the network structural limit, related to the cross sections of MV overhead lines and cables and cannot be solved unless significant investments are put in place. The base case scenario is shown as a low loading in the most part of the grid, resulting in an apparently unnecessary oversize. However, the loading increase showed an important consequence of the good line sizing to maximize the amount of distributed generation installed in the feeder. It is important to say that these thermal limits are reached for a few hours, so the introduction of elements to shift the power injection in time could result in a hosting capacity increase of the feeder. Moreover, it can be appreciated that the overall hosting capacity in all cases is set by the line thermal limit. Overload of branches is the first limit affected or the most badly impacted. The reverse power flow is a real problem, as the red and yellow lines show in Figure 19, when the generation is higher than the demand, so when current flows from the feeders to the primary station.