# A New SEPIC-Based DC-DC Converter with Coupled Inductors Suitable for High Step-Up Applications
## 6 Applicability of the Proposed SEPIC Converter in a PV System
### Experimental Results of the PV System Using the Proposed SEPIC-Based Converter  
In this section, the novel proposed converter supplied by two PV panels connected in series and having P&O as a MPPT method is presented. For solar irradiance and PV temperature measurement, a pyranometer [70] was used. The pyranometer produces a voltage (\(V_{GPU}\)) proportional to the incident solar irradiance. For the PV temperature measurement (\(T_{PV}\)), the other pyranometer voltage (\(V_{TPV}\)) is measured and the temperature can be found according to the formula [70]:  
\[T_{PV}=\frac{V_{TPV}-1.84}{0.092}\ [^{\circ}\mathrm{C}] \tag{39}\]  
In Figures 29 and 30, for an irradiance of 885.6 W/m\({}^{2}\) the corresponding \(V_{GPU}\) = 7.38 V and \(V_{TPV}\) = 8.24 V. According to (39), the PV temperature is equal to \(T_{PV}\) = 69.56 \({}^{\circ}\)C. In Figure 29, the oscilloscope capture shows the start-up, which lasts approximately 5 s.  
In the down to up order, the first waveform drawn in dark-blue and labeled \"_Vin_\" is the input voltage. In the beginning, it is equal to the open-circuit voltage of the PV panels, of about 42 V, and then it decreases according to the characteristic to about 35 V. The MPP is reached after approximately 5 s, and this can be seen on the third waveform labeled \"_Vout_\" (in purple). The P&O algorithm continuously modifies the duty cycle by increasing and decreasing it with one step. Because the irradiance is constant, the converter is maintained around the same OP. The output voltage in this case is equal to 110 V. The second signal is the input current, labeled \"_Iin_\" and depicted with cyan. The fourth waveform presented, labeled \"_Pin_\", is the instantaneous power at the input provided by the PV cell. This power is displayed on the oscilloscope, computing the product between the voltage and current at the input. To demonstrate the functionality of the P&O control algorithm, the input power needs to be maximized. As the current increases and the input voltage slightly decreases, the input power provided by solar conversion increases and proves the correct behavior of the control algorithm. In Figure 30, the same waveforms are shown in different order: \"_Vin_\", \"_Vout_\", \"_Iin_\" and \"_Pin_\" for the following scenario. Because the measurements were performed on a sunny day, without any cloud in the sky, in order to prove the functionality of the converter driven by the P&O algorithm, after about 10.4 s, a part of the PV panel was shaded for approximately 6 s. The input voltage and power decrease can be observed in Figure 30, and the steps of the P&O implementation are also visible, validating the effectiveness of the P&O implementation.  
Figure 28: Output voltage against time during the proposed scenario.  
Figure 30: Oscilloscope waveforms for: input voltage _“Vin”_(dark-blue), output voltage _“Vout”_(purple), input current _“lin”_(cyan) and input power _“Pin”_(red), in down to up order.  
Figure 29: Oscilloscope waveforms at start-up for: input voltage _“Vin”_ (dark-blue), input current _“lin”_ (cyan), output voltage _“Vout”_ (purple), and input power _“Pin”_ (red), in down to up order.