## 3 Results and Discussion
### Analysis of the Relationship between the Grid Voltage and the Power Generated by the Inverters
If the most unfavourable case is considered in this graph, the maximum PV power that could be injected in each phase at the same point would be around 50.7 kW. Above this power, the value of the grid voltage in the different phases could be higher than the maximum value of 253 V recommended by the regulations. Using the same procedure, an estimation of the hosting capacity was obtained in the rest of the PV installations, values that are shown in Table 5.  
The results show that, as previously indicated, installations 3 and 6 were the most resilient with respect to PV production, and they would therefore admit a greater increase in the PV capacity that could be added per phase, in both cases more than 300% of the power already installed. However, the most unfavourable slopes were considered for this calculation. Given that in some of the installations these maximum slope values had a small incidence and have only occurred during a few weeks in the three-year period, one could consider the option of further increasing the installed renewable capacity, considering lower slope values, and applying for example curtailment in the injection during these times of higher voltage increases. Although the calculated hosting capacity has taken into account only the value of the nominal voltage at the PCC, the thermal limits of the network components should also be considered, although in LV networks and with the aim to limit voltage drops in conductors and by life-cycle cost aspects, usually larger conductors than those dictated by thermal limits are used [46]. Furthermore, to avoid reverse power flows to the transformer at the head of the line, the installed PV power should not exceed the maximum demand of the loads connected to the same distribution network during their peak production hours. The rating of an embedded generator connected below a particular transformer minus the minimum load in the same area must not exceed the maximum load in that area [46]. The analysis of these latter aspects is beyond the scope of this paper, as this information is not available to the authors, but, in any case, the most unfavourable result should be applied. The results show that the values recorded by the inverters of the plants allow an assessment to be made of the impact that this type of installation is having on this grid parameter. Although the production of the PV plants leads to an increase in the grid voltage, it is not significantly affecting this parameter, which has already shown a variation in its value apart from the production of these renewable installations. However, obviously the hosting capacity of each network is limited, and it would have to be estimated for each grid parameter, in order not to give rise to future problems, or to plan the establishment of regulation mechanisms or control strategy to make this capacity even higher. The uses of  
Figure 23: Maximum values of PV power that would be admitted in each phase in the network at the PCC of installation 3, depending on the maximum (green line), average (black line) and minimum (yellow line) slopes and \(Y\)-axis intercept. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & \multicolumn{2}{c}{**Maximum Nominal**} & \multicolumn{2}{c}{**Increase in Power**} \\  & **Current Nominal** & **Power Per Phase** & **Inverse** & **Compared to the** \\  & **Power of the** & **Power Per** & **with the Most** & **Allowed (kW)** & **Current Installed** \\  & **Plant (\&W)** & **Phase (kW)** & **Unfavourable** & **Power Per Phase (\%)** \\  & & & **Slope (kW)** & & \\ \hline PV Installation 1 & 672.0 & 224.0 & 364.7 & 140.7 & 62.8 \\ PV Installation 2 & 217.6 & 72.5 & 142.0 & 69.5 & 95.8 \\ PV Installation 3 & 36.7 & 12.2 & 50.7 & 38.5 & 314.2 \\ PV Installation 4 & 22.2 & 7.4 & 18.2 & 10.8 & 145.7 \\ PV Installation 5 & 100.2 & 33.4 & 60.0 & 26.6 & 79.7 \\ PV Installation 6 & 17.8 & 5.9 & 25.5 & 19.6 & 329.3 \\ \hline \hline \end{tabular}
\end{table}