# Investigation of the Automatic Monitoring System of a Solar Power Plant with Flexible PV Modules
## 2 Materials and Methods  
An automatic monitoring system was created to monitor the working parameters of the solar power plant with flexible modules. A conceptual diagram of this system is presented in Figure 1. The solar power plant consists of two flexible silicon modules (monocrystalline 140 W; 18.72 V; 7.48 A; 1090 \(\times\) 700 \(\times\) 3 mm) based on flexible plastic.  
The automatic parameter monitoring system consists of two stages. The first stage consists of a microcontroller-based system. The basis of this stage is the PIC24 FV32 KA302 microcontroller and supporting parts such as a DC/DC converter module and an RS232--TCP converter module. This microcontroller is a 16-bit PIC24 series microcontroller developed by Microchip Technology with 32 KB of Flash memory and 2 KB of RAM. It supports 3.3 V and 5 V operating voltages, making it versatile for use in both low- and medium-voltage devices. This microcontroller has low power consumption and is suitable for low-power embedded systems. In addition, it integrates various peripherals such as analog-to-digital converters (ADCs), timers, serial communications (UART, SPI and I\({}^{2}\)C) and PWM generation. Because of these features, the PIC24 FV32 KA302 is often used in medical devices, sensor interfaces, industrial controllers and energy-efficient embedded systems where reliable and efficient performance is required. Power data (I and U values) are also received by the wattmeter modules (arranged on batteries and solar panels) in the first stage. The wattmeter modules are based on the PIC16F1516 microcontroller (an 8-bit microcontroller belonging to the PIC16 series). The purpose of the first stage is to collect data from the sensors and transfer them to the main PLC (US10-B10-T24) controller module. The second stage of the monitoring system consists of an industrial programmable controller (PLC) which receives data from the first stage. The PLC has communication with the PC where the data are stored and the HMI process visualization panel. The operation of the monitoring system was tested by charging two AGM-type batteries (40 Ah and 12 V). PWM (3 IPSSOLU20)- and MPPT (3 IPSSMPTT10)-type charging controllers were used for charging. The study included a comparison of the efficiency of the loading process of waste loading controllers. Another part of the solar electric load was Fito LED strips emitting light of a certain wavelength for lighting the plants.  
The reliability of data transmission is ensured by the PIC24 FV32 KA302 microcontroller, which integrates various peripherals that allow for the efficient collection and processing of data from the wattmeter modules. The stability of the connection is ensured by the RS232--TCP conversion module, which allows data transmission to PLC and PC, and a repeated data transmission system is used to avoid data loss. The optimization of data transfer is achieved by efficient communication protocols such as I\({}^{2}\)C between microcontrollers and RS232-TCP conversion, allowing fast and stable data transfer between the first and second stages of the monitoring system. In addition, optimizing the transmission frequency helps to reduce delays and ensure that all parameters are transmitted and recorded in the database on time.