# Investigation of the Automatic Monitoring System of a Solar Power Plant with Flexible PV Modules
## 3 Results and Discussion  
This research used a solar power plant consisting of two flexible solar modules with a power of 140 W each. The experiment was carried out in an open outdoor environment on a sunny day with an average temperature of about 25 \({}^{\circ}\)C to ensure a maximum solar radiation intensity of 800 W/m\({}^{2}\). The PV modules and other specific elements used in this study are typical of solar energy systems, but they also represent innovations that improve system efficiency. Flexible solar modules that can adapt to different surfaces make it easier  
Figure 1: Conceptual diagram of the system for monitoring the working parameters of a solar power plant with flexible modules. to integrate solar systems, while PWM and MPPT technologies optimize energy flow and battery charging in response to changing weather conditions. Such solar power plants can be widely used for various applications due to their versatility (such as charging various mobile devices, powering IoT systems and charging mobile robots/drones). Flexible solar panels are formed on a flexible plastic substrate. Such a base expands the application possibilities of solar modules, as it is possible to adapt solar modules to a wider range of surfaces that are not necessarily perfectly flat or smooth. In addition, the total mass of such solar modules, up to 10 times or even more, is significantly lower than that of rigid solar modules. In order to be able to predict and ensure the stable operation of the PV system, a reliable flexible automatic monitoring system of operating parameters is required. A detailed conceptual diagram of the monitoring system considered during this study is presented in Figure 2. The process of designing and forming the design of this scheme is a part of scientific research, since the working efficiency, universality, speed, etc., of the monitoring system depends on the structure of the concept. While investigating the work of the monitoring system, the battery charging process was initiated and Fito LED strips emitting light of a certain wavelength were powered. Digital power meters are connected to each output of the solar panel, to the battery terminals and to the power circuit of the Fito led strips, which are made on the basis of the PIC16F1516 microcontroller. The data from the digital wattmeters go to the MCU main processor based on the PIC24 FV32 KA302 microcontroller. This part of the circuit forms a digital packet of data and transmits it to an industrial PLC module, which, using an Internet connection, transmits the data to a central computer, recording it in a database. Two methods are used for charging batteries: one charging process is performed using a PWM-type controller, while the other is using an MPPT-type controller [1; 2; 3; 4]. As can be seen, the monitoring system of the working parameters of the solar power plant consists of two stages: in the first stage, based on the MCU controller, data are collected from digital wattmeters, while in the second stage, based on the industrial PLC, the data are analyzed and transmitted to the central PC, and the work process is displayed on the HMI screen. Figure 2: The main block diagram of the monitoring system. As mentioned earlier, a digital wattmeter based on a PIC16F1516 microcontroller was designed for each power input point. The design of the wattmeter is part of this scientific process, because only an original, specially adapted wattmeter and its architecture can qualitatively ensure the stable operation of this experimental monitoring system. This power measurement module also has an additional RAM (PCF 8570) memory module, which is high-speed and helps ensure stable data transfer to the MCU module. The data transfer between the RAM and the main controller takes place using the I2C protocol. ACS (Current Sensor) 7 modules are used to measure current and voltage, which digitally transmit the data to the outputs of the microcontroller (Figure 3).