## 3 Results
### Experimental Results  
As in the simulation results, different case studies are proposed in order to evaluate the behavior of the microinverter in both the DC-DC stage and the DC-AC stage. The data were measured with a SIGLENT SHS1062 oscilloscope and a sampling frequency of 25 kHz. For the DC-DC stage, the voltage and current values of the solar panel were measured at an irradiance of approximately 263 W/m\({}^{2}\) so that the ideal power was 79 W. In Figure 37, the current and voltage of the panel with filtered and measured data can be observed. In Figure 38, the input power is shown, where it can be deduced that the MPPT algorithm, in conjunction with the 2P2Z control, managed to obtain the maximum power from the panel. However, oscillations occurred, mainly due to high-frequency noise, so they were eliminated with the designed digital filters. Figure 37: Current and voltage of the solar panel when the irradiance was 263 W/m\({}^{2}\). Figure 36: Increase in \(V_{bus}\) in order to regulate the active power. Reference value: \(Q_{ref}=0\) VAR. In addition to having an on-grid operating mode, the microinverter can be configured for an off-grid mode. Figure 39 shows the current \(i_{g}\), the output voltage, and the \(THD_{i}=7.63\%\) obtained with this configuration, which were in a range close to that suggested by the IEEE 1547 standard [31]. This case study was carried out to verify the control algorithm, PWM configuration, and microinverter operation before synchronizing with the grid. After verifying the proper functioning of the microinverter in the off-grid mode, the synchronization stage with the grid and the active and reactive power control were implemented to obtain the results for the DC-AC stage. In Figure 40, the PI voltage control response, which was activated at 1.2 s, is shown. It is evidenced that the DC bus voltage managed to follow the 270 V reference without steady-state error and with a settling time of approximately 0.5 s.  
Figure 38: Power obtained from the solar panel. Figure 39: Output current and voltage of the microinverter configured in the off-grid mode. Then, \(P_{ref}\) was set to be equal to \(P_{max}\), and \(Q_{ref}\) was defined with the values of 0, 20, 40, \(-\)20, and \(-\)40 VAr to analyze the active and reactive power control. Figure 41 shows that the P and Q control supplied capacitive and inductive reactive power according to the defined reference.In addition, the injected active power is presented. When \(Q_{ref}\) changed from 40 to 0 VAR, the injected current of the microinverter \(i_{g}\) and the grid voltage \(V_{LN}\) were compared (Figure 42), and a difference in the phase shift between the two waves of approximately 35 \({}^{\circ}\) a 0\({}^{\circ}\) was shown. Figure 41: Active and reactive power supplied by the microinverter during the changes in \(Q_{ref}\). Reference value: \(V_{ref}=270\) V.  
Figure 40: Voltage of the DC bus. The microinverter control was activated at 1.2 s. \(V_{ref}=270\) V.  
Similarly, the reactive power reference values for the microinverter must be established with a minimum power factor of \(\pm\)0.85 or \(\pm\)53% of the total reactive power to function correctly and guarantee the integrity of its components. A scenario with a 100 W incandescent light bulb was proposed to analyze the interaction of the microinverter with the grid (Figure 43). In the beginning, the microinverter control was off and, after 4.7 s, it was activated. The microinverter managed to partially compensate the active power consumption of the load when the control system was on. From the previous case studies, some indicators were calculated to evaluate the performance of the microinverter. The combined efficiency of the DC-DC stage and the DC-AC stage was, on average, 88%, and the maximum was 91%, which was similar to that found in [19]. In addition, the total harmonic distortion was calculated (Figure 44); \(THD_{v}=9.4\%\) and \(THD_{i}=24.9\%\) were obtained, which are values that were outside the range established by the IEEE 1547 standard [31].