# Centralized MPPT Control Architecture for Photovoltaic Systems Using LoRa Technology
## 3 Experimental Setup
### Control System and Wireless Implementation  
#### 3.3.1 Hardware  
Figure 12 illustrates the control circuit schematic. The current and voltage signals coming from the converter and the signals coming from the irradiance and temperature sensor were connected to an Arduino MKR WAN 1300 board (Arduino S.R.L., Monza, Italy). The duty cycle signal was transmitted from the Arduino board to the DC-DC converter. The Arduino board served as the sensor and actuator node. As for the computing node, it  
\begin{table}
\begin{tabular}{l c c} \hline
**Property** & **Value** & **Unit** \\ \hline \hline \begin{tabular}{l} Switching frequency \\ Maximum input voltage \\ Maximum output voltage \\ Maximum output voltage \\ Maximum input current \\ \end{tabular} & \
\begin{tabular}{l} 20 \\ 60 \\ 200 \\ 20 \\ 20 \\ 20 \\ 20 \\ 20 \\ \end{tabular} &
\begin{tabular}{l} kHz \\ V \\ V \\ V \\ V \\ V \\ V \\ V \\ \end{tabular} \\ \hline \end{tabular}
\end{table}
Table 2: Details of the DC–DC boost converter used in the experiments.  
Figure 11: Location of the PV module. (**a**) Plan view. (**b**) Photographic image, as seen from A.  
was composed of a computer running MATLAB, and it was connected to another MKR WAN 1300 via UART. Both MKR WAN 1300 modules used LoRa at the 868 MHz frequency band for communications.  
The authors of this paper developed a cost-effective prototype for the sensor and actuator node. This prototype integrates an Arduino MKR WAN 1300 along with electronic components designed for measuring and scaling sensor readings. The voltage and current signals from the power converter have a range of 0-10 V, with the scale factors detailed in Table 2. The Si-V-10 TC-T irradiance and temperature sensor, whose specifications are available in [47], generates 0-10 V signals, which are converted to 0-3.3 V using voltage dividers. Additionally, a BS170 MOSFET was employed to amplify the PWM signal. Figure 13 provides a more detailed schematic of the sensor and actuator node.  
Figure 12: Diagram of the control system used for the experiments.  
Figure 13: Schematic of the sensor and actuator node.  
The MKR WAN 1300 module within the sensor and actuator node was programmed using the Arduino IDE 2.0.3 and Visual Studio Code 1.87. It transmitted data, including PV panel voltage and current, irradiance, and cell temperature, as well as converter voltage and current outputs, to the computing node. Furthermore, it received a duty cycle signal from the computing node, which was then written to a PWM output on the Arduino board.  
The primary component of the computing node was a computer executing MATLAB code. The MKR WAN 1300 was linked to the computer through the UART port. The serial communication between these devices was configured using the Arduino IDE. The MATLAB code was used to read the serial port, capture the frames transmitted by the sensor and actuator node, process the received data, and to generate a frame containing the computed duty cycle for the PWM. The duty cycle was computed through both the P&O and SMC methods, as described in Sections 3.3.2 and 3.3.3.