## 3 Results
### Results of Sensitivity Analyses
#### 3.2.1 Sensitivity to Acquisition Cost of Li-Ion Batteries  
For this analysis, the acquisition cost of Li-ion batteries was multiplied by factors from 0.1 to 2, while the cost of lead-acid batteries was unchanged. Figure 9(a) shows the results of the optimal PV system and Figure 9(b) that of the hybrid system, both for the winery case. As expected, below a certain factor where the lines cross, the absolute optimal systems contain a Li-ion battery, while above that factor, they include a lead-acid battery. In the five case studies, the slope of the line of the NPC (with Li-ion battery) of the optimal PV system is greater than that of the optimal hybrid system.  
The value of the factor with which both types of battery obtained the same NPC of the optimal system was different depending on the case study and the type of system (PV or hybrid). These values are shown in Table 12. In the five case studies, this value was higher for the hybrid system than for the PV. Consequently, the reduction in the acquisition cost of Li-ion batteries necessary for their entry into the absolute optimum of hybrid systems was less than that of PV systems.  
Regarding the size of the battery, in the five cases, both PV and hybrid, the acquisition cost of Li-ion batteries influenced their size (their capacity) in the optimal system. Figure 11 shows the graphs corresponding to the winery case. In both PV (a) and hybrid (b) systems, as the acquisition cost of Li-ion batteries decreased, the capacity of the battery increased. In addition, the decrease in capacity with the increase in cost tended to a limit, especially in PV systems.  
Figure 10: Sensitivity analysis on the NPC of the optimal systems with lead-acid and Li-ion batteries for the winery case, based on the acquisition cost of Li-ion batteries: (**a**) PV system; (**b**) Hybrid system.  
Variations in Li-ion battery acquisition cost were accompanied by variations in various elements of the system. Figure 11(a) shows a graph corresponding to the PV system of the winery case. The reduction in battery capacity, motivated by its increase in cost, was accompanied by an increase in the power of the PV generator. On the contrary, the higher the battery capacity, the lower the PV generation power. Thus, a lower production of the PV generator was compensated by taking advantage of a part of the surplus energy, through a battery with a higher capacity.  
By contrast, in the hybrid system of the same case (the winery), as shown in Figure 11(b), the reduction in battery capacity shown in Figure 11(b) was accompanied by a reduction in the power of the PV generator, while the increase in energy production was assumed by the  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Case** & **PV System** & **Hybrid System** \\ \hline Winery & 0.81 & 0.83 \\ Irrigation pumping & 0.69 & 0.79 \\ Pig farm & 0.64 & 0.86 \\ Single-family home & 0.96 & 1.30 \\ Second home & 1.59 & 1.60 \\ \hline \hline \end{tabular}
\end{table}
Table 12: Factor applied to the acquisition costs of Li-ion batteries below which they entered into the absolute optimal systems.  
Figure 11: Sensitivity analysis on the battery capacity in optimal systems for the winery case, based on the acquisition cost of Li-ion batteries: (**a**) PV system; (**b**) Hybrid system.  
Figure 12: Sensitivity analysis on elements in optimal systems for the winery case, based on the acquisition cost of Li-ion batteries: (**a**) PV power and battery capacity in the PV system; (**b**) PV power and energy from diesel in the hybrid system.  
diesel genset. In other words, the increased production of the diesel genset compensated for both the lower capacity of the battery and the lower power of the PV generator.  
All these behaviors occurred in all case studies, to a greater or lesser extent. In PV systems, these variations were limited, since a minimum of accumulation was required for the operation of the system. Unlike PV systems, the presence of dispatchable generation allowed greater flexibility to hybrid systems.