# A Comparative Study of Storage Batteries for Electrical Energy Produced by Photovoltaic Panels
## 3 Simulation Results  
The model developed in MATLAB Simulink was employed to simulate the functioning of each battery type without modifying any other structural parameters. The variations in the photovoltaic panel parameters were identical for both battery types, and are presented in Figure 6. The electric power supplied by the photovoltaic panels is modified as a function of the variation in solar radiation intensity. Under a solar radiation intensity of 1000 W/m\({}^{2}\), the photovoltaic panels will produce 0.3 kW of electrical power. The variations in the Lead-Acid battery parameters as a function of the variation in solar radiation intensity are presented in Figure 7, and the variations in the Lithium-Ion battery parameters as a function of the variation in solar radiation intensity are presented in Figure 8.  
Figure 8: Variation in parameters of Lithium-Ion battery supplied by photovoltaic panels.  
Figure 7: Variation in parameters of Lead–Acid battery supplied by photovoltaic panels.  
Based on the values of the electric energy storage battery parameters, the diagram shown in Figure 9 was drawn. The parameters shown in this diagram are as follows: SOC_LA--the charging status of the Lead-Acid battery; SOC_Lt_I--the charging status of the Lithium-Ion battery; Ib_LA--the current intensity of the Lead-Acid battery; Ib_Lt-I--the current intensity of the Lithium-Ion battery; Ub_LA--the voltage at the terminals of the Lead-Acid battery; and Ub_Lt-I--the voltage at the terminals of the Lithium-Ion battery.  
The measurement units for the values presented on the y axis in Figure 8 are as follows: the loading status of the battery SOC is measured in %; the current intensity in the battery, Ib, is measured in A; and the voltage at the terminals of the battery, Ub, is measured in V. The analysis of the results presented in Table 1, the diagram in Figure 9,  
\begin{table}
\begin{tabular}{c} **Battery** \\ **(Lithium-Ion)** \\ \end{tabular} \\ \hline
0 & 44.999 & 44.999 & 3.335 & 3.08 & 11.846 & 12.898 \\ \hline
4 & 44.996 & 44.996 & 3.01 & 3 & 11.843 & 12.897 \\ \hline
8 & 44.996 & 44.995 & \(-\)3.06  
and the characteristics of variation in the battery parameters shown in Figures 7 and 8 leads to the following conclusions: the values obtained for each battery's charging status (SOC) are practically equal, while the current intensity of the Lead-Acid battery is a little higher than that of the Lithium-Ion battery. When the batteries are discharged, the current intensities of both batteries have positive values, and when batteries are charged, their current intensities have negative values. In this study, a receptor circuit was not connected to the battery. Battery discharge occurs when the intensity of solar radiation decreases and the photovoltaic panels cannot supply the electrical power needed in order to charge the battery. At t = 20 s, the current intensity of the Lead-Acid battery is Ib_LA = \(-\)2.999 A, and the current intensity of the Lithium-Ion battery is Ib_Lt-I = \(-\)2.883 A. Furthermore, the voltage at the Lead-Acid battery terminals is lower than the voltage at the Lithium-Ion battery terminals: at t = 20 s, the voltage of the Lead-Acid battery is Ub_LA = 11.967 V, and the voltage of the Lithium-Ion battery is Ub_Lt-I = 12.914 V. In addition, the electric power of the Lead-Acid battery at t = 20 s is 35.88 W, and the electric power of the Lithium-Ion battery is 37.23 W. Based on these values, it can be concluded that the Lithium-Ion storage battery exhibits higher performance than the Lead-Acid storage battery, because it is charged with a higher electrical power.