## 4 Simulation Results and Discussion
In Figure 10, the simulated behavior of both P&O and Td-MPPT while being subjected to a rise in irradiance from 100 W/m\({}^{2}\) to 1000 W/m\({}^{2}\) at a changing rate of 5000 W/m\({}^{2}\)/s is displayed. This graphic format allows observing better the classical P&O drift, although it makes it harder to observe oscillations around MPP during static irradiance. It can be observed that both P&O and Td-MPPT start around the theoretical MPP represented in the red dashed line. However, as MPP shifts towards the right with increasing irradiance, P&O keeps perturbing away from the optimal value until the perturbation produces a power reduction significant enough to counter the power increase caused by irradiance increases. In contrast, Td-MPPT tracks the theoretical MPP very close through its trajectory. Figure 9: Simulated duty ratio–voltage curves of the boost converter and the solar panel UP-M155M curves for all static irradiance values described in the EN50530:2010 standard. A format that includes time in the figure is presented from now on to better illustrate oscillations around the theoretical MPP. The classical P&O behavior during the complete test described in Table 2 is shown in Figure 11a. The graph shows the simulated voltage and power (solid-blue) and the theoretical ideal at MPP (dotted-red). It can be noted that the algorithm tracks relatively well during the first iterations of both regions. In contrast, as the slopes become steeper in later iterations, the P&O displays significant drift from the MPP, negatively affecting the power output and, consequently, efficiency. It must be noted that the simulation results correspond with the behavior described in the literature [13; 19; 35]. The dP-P&O in Figure 11b shows fewer and smaller excursions away from MPP than the P&O. The proposed Td-MPPT displayed in Figure 11c does not exhibit drift issues and tracks the most effective during the complete test. Due to this, the overall efficiency of Td-MPPT reaches 99.68%, while dP-P&O achieves 99.56%, and classical P&O drops to 97.26%. Figure 10: Simulated behavior of P&O (**a**) and Td-MPPT (**b**) when subjected to a steady increase from 100 W/m\({}^{2}\) to 1000 W/m\({}^{2}\) at a changing rate of 5000 W/m\({}^{2}\)/s. Figure 12 shows the dynamic efficiency of the tested algorithms in response to the trapezoidal profiles of the test for the low to medium (solid-blue) and the medium to high (dashed-red) sections. It can be noted that P&O efficiency in Figure 12a deteriorates rapidly as the slope becomes steeper with each iteration. However, efficiency stops decaying after a certain point and rises with even steeper irradiance slopes. This phenomenon occurs because the P&O does not have enough time to drift away from the MPP with the fastest repeating trapezoidal irradiance profiles as with the slower ones. This contrast between fast (700 W/m\({}^{2}\)/s) and the fastest (5000 W/m\({}^{2}\)/s) irradiance slopes can be observed in Figure 13. Similar results were observed in [19; 36] as it was noted that the P&O algorithm did not show significant drift from the MPP when being subjected to step-shaped irradiance changes. Figure 11: Behavior of the P&O (**a**), dP-P&O (**b**) and Td-MPPT (**c**) during the full simulation: simulated PV voltage (solid-blue) and V\({}_{\text{MPP}}\) (dotted-red), corresponding PV power simulated (solid-blue), and P\({}_{\text{MPP}}\) (dotted-red). It can be noted that the efficiency for dP-P&O in Figure 12b modification does not decay as fast with steeper slopes as with the classical P&O. However, some degree of efficiency loss is displayed as the irradiance slope rises. Contrary to what is observed with these two algorithms, the proposed Td-MPPT in Figure 12c shows an almost imperceptible reduction in tracking efficiency even at the steepest irradiance slopes.