# Centralized MPPT Control Architecture for Photovoltaic Systems Using LoRa Technology
## 1 Introduction
It increases deployment flexibility, reducing signal wiring and improving the scalability of the applications [19; 20; 21; 22; 23]. In [24], [PERSON] et al. proposed a centralized microgrid controller by means of LoRa communications aimed to connect/disconnect loads to the utility grid. Their simulation results showed that a LoRa protocol can handle the requirements for that purpose, although they did not test the MPPT control for the PV modules of the microgrid. [PERSON] et al. [25] analyzed the feasibility of a wireless deployment with LoRaWAN. The storage batteries required by the gateways were fed from a PV plant. However, they did not mention the use of this LoRa network for operating the PV plant itself. [PERSON] et al. proposed a LoRa-based LPWAN for PV plants in [26]. They also carried out an experimental setup, but they focused on real-time data monitoring and plant management rather than MPPT control. Other researchers reviewed low-cost, Internet of Things (IoT) solutions in PV power plants, including Zigbee and LoRa (although only for monitoring purposes),thereby concluding that these technologies will be widely deployed at PV systems in the near future [27, 28]. In [29], [PERSON] et al. tested a LoRa RF setup to avoid overloading the transformers and over-voltage problems caused by a sudden injection of power from solar PV plants. They used LoRa to transmit control commands for smart inverters in order to control its power factor and to perform reactive power compensation. [PERSON] et al. [30] proposed a low-cost, centralized, and wireless MPPT controller that was designed for building-integrated PV systems (although they used ZigBee instead of an LPWAN such as LoRa). In [31], the authors of this article also considered sending control signals through wireless technologies to improve the operation and QoS of solar PV systems by means of a centralized, wireless MPPT controller using XBee technology. However, the range limitations of XBee can complicate its use in very remote PV subsystems. The introduction of LoRa technology presents several advantages when compared to this previous work, as LoRa is a low-cost and low-consumption technology that was specifically designed for long-distance applications in the range of several kilometers. The use of LoRa's CSS enhances robustness, reducing data loss. Finally, LoRa also enables connecting to LoRaWAN networks, thereby not only enhancing the potential for decentralized control, but also enabling scalable communication within a broader network infrastructure. A proof-of-concept prototype that involved a rooftop installation at the Faculty of Engineering, Vitoria-Gasteiz (UPV/EHU), was built to validate the presented approach. This prototype involved a PV subsystem and a central computer running MATLAB R2022b for the execution of the MPPT control algorithms. These devices were connected by means of a point-to-point LoRa network, which was set up by means of Arduino MKR WAN 1300 LoRa boards. Different MPPT algorithms were programmed in MATLAB for experimentally validating the presented approach, namely P&O and SMC controllers. The main aim of this work is to prove the suitability of LoRa communications for a centralized MPPT control method. Although we put focus on P&O and SMC controllers to perform MPPT, any other controller sufficiently robust and tolerant of relatively low transfer rates could be used. Additionally, the proposed controllers can be combined with artificial neural networks (ANNs) to improve their response time. The obtained results suggest that the proposed low-cost approach can be implemented over a LoRaWAN network, in which a central node executes, in parallel, a number of MPPT controllers for distinct PV subsystems, possibly with different orientations and shading patterns. The remainder of this article is structured as follows: Section 2 describes the technologies used in this work, including the PV system and the use of LoRa communications. It also proposes a centralized architecture to execute MPPT controllers for different PV subsystems.