# Centralized MPPT Control Architecture for Photovoltaic Systems Using LoRa Technology
## 2 Centralized MPPT Architecture Based on LoRa
### Configurations of PV Systems  
A PV system consists of multiple PV modules that span a peak of powers from a few hundred watts, as in a small rooftop installation, to hundreds of megawatts, as in the world's largest photovoltaic plants. The control system of a grid-connected PV system has a dual-stage setup: MPPT and grid interface control [33]. The second stage is out of the scope of this article but is mentioned for context.  
Figure 5 shows four different configurations of grid-connected PV systems. In the first option, as shown in Figure 5a, there is a central power conversion system that includes DC-DC for MPPT control and DC-AC as the interface to the grid. This approach is valid for PV plants on open, level areas, where all the PV modules have the same orientation and there are no external elements that could cast uneven shadows. In this configuration, theone MPPT control system applies to all of the PV modules, and the only measure against them not functioning at the same operating point is the bypass and blocking diodes.  
The second configuration is depicted in Figure 5b. Here, each string of PV modules is connected to one DC-DC converter that optimizes its power output [40]. Figure 5c has a similar but more granular approach because all of the PV modules have their own DC-DC converter. In module-level DC-DC conversion, every PV module is linked to an individual DC-DC stage so that every module can be tracked to operate at the required operating point [41]. This is known in the literature as a module-integrated converter (MIC) [30]. We propose that the set point of the duty cycle sent to each of the DC-DC converters be calculated at a centralized MPPT controller for both string converter and MIC configurations. This way, a central computing node can independently run MPPT algorithms for various PV subsystems. This can be performed via wireless communications, as explained in the following subsections.  
Figure 5: Configurations of PV systems. (**a**) With centralized converters. (**b**) With a central inverter, string DC/DC converters, and a centralized MPPT. (**c**) With module-integrated converters and a centralized MPPT. (**d**) With module-integrated inverters.  
For completion, a fourth option is shown in Figure 5d, representing module-level DC-AC conversion, where every PV module has its own inverter. Each inverter is responsible not only for MPPT control, but also for grid interfacing.  
The primary drawback associated with the MIC architecture is manufacturing cost. However, the potential for significantly higher energy yields is notable, especially when dealing with situations of partial shading. For instance, the simulations conducted by [PERSON] et al. in [42] demonstrated that a fully re-configurable PV array, comprising 24 modules using MICs, could increase the power output up to 23% in comparison with a fixed 684p configuration with one converter. Nevertheless, it is important to note that there is no ideal architecture for PV systems. The right choice will depend on various factors that can have an impact on the investment cost and on the energy yield, such as shadows of buildings, latitude, or prevailing weather conditions.