# A Power-Line Communication System Governed by Loop Resonance for Photovoltaic Plant Monitoring
## 1 Introduction  
An overwhelming amount of confidence is placed within the potential of renewable energy (RE) systems to meet the global demand necessary to thwart the occurrence of additional cumulative greenhouse gas emissions (GHG), induced by fossil fuel use. This is of course envisioned to occur through the rapid creation of new renewable installed capacity and the decommissioning of conventional power plants. Photovoltaic (PV) solar, in particular, has seen a significant rise in installation as a function of the steadily decreasing costs of the technology. For instance, an 85% cost reduction in global utility-scale PV levelized cost of electricity (LCOE) between 2010 and 2020 was observed, corresponding to a 1600% (42 GW:2010, 714 GW:2020) cumulative increase in installed capacity [1]. Comparably within the same decade, onshore wind displayed a cumulative increase in capacity of 293% (178 GW:2010, 699 GW:2020). This trend evokes great prospects for continued global PV proliferation and warrants the interest that has been seen among studies to uphold the potential of the technology through the development of multiple PV monitoring systems and algorithms, as documented in [2; 3; 4]. Fundamentally, ensuring the health of PV plants are preserved as they continue to gain significant prominence, especially with their observed disposition toward a variety of physical faults and failures [2]. Amongst the different PV monitoring methodologies, solar module level I-V (current-voltage) curve tracing was utilized in the genesis of our precursory work to this paper, not only due to the accuracy of the method but also in large part because of the ability to perform the method with integrated low-cost electronics [4]. However, despite the demonstration of the feasibility of our preliminary monitoring system, further cost reduction is always necessary to ensure system affordability is universally flexible across the widest range of consumers or socioeconomic groups. The functionality of monitoring systems can aid with building long-term consumer trust in the RE industry by bolstering the general outlook of RE technologies as reliable, long-term investments. As such, it is paramount that continuous, cost reduction be applied to these systems to incentivize the consumer base to integrate them with their PV installations. The communication block for I-V tracing is a section that can be designed to further regulate the cost reduction of the system. Several studies have utilized differing wired and wireless communication strategies assessing their cost, transmission speed, and efficiency. Ref. [3] presented a brief review of some of these studies and highlighted the advantages and limitations found among them. The review communicates that wired methods such as coaxial cables and fiber optics, present high transmission rates with low attenuation but are ascribed with limitations in coverage and expense respectively. Wireless methods such as Satellite, Wi-Fi, Bluetooth, GSM, Radio-Frequency transmission, and others are either characterized by fast transmission rates plagued by high expense and frequency regulations, low-cost with limitations due to interference effects, and transmission distance, or high expense and slow transmission. Refs. [3; 5] report the popular rationale for the use of the wired strategy of power-line communications (PLC) in PV monitoring. PLC systems in PV environments can provide transmission speeds up to 200 Mbps while subverting the costly manner of several wired and wireless methods due to their innate topology of using the same DC-PV power lines as a transmission medium. The following section will review the current PLC configurations found in literature. In [6] the authors proposed a frequency shift-keying (FSK) method at a carrier of 132.5 kHz with the use of the commercial ST7540 FSK power line transceiver (with an internal power amplifier) and Microchip PIC18 LF4620 microcontroller to transmit along a 10-module series string.