# Investigation of the Automatic Monitoring System of a Solar Power Plant with Flexible PV Modules
###### Abstract  
During this research, an automatic monitoring system was developed to monitor the working parameters in a solar power plant consisting of two flexible silicon modules. The first stage of the monitoring system relies on a microcontroller, which collects data from wattmeter modules made using a microcontroller. This tier also includes DC/DC converter and RS232-TCP converter modules for data transfer. The second stage, the industrial PLC, receives data from the first stage and transmits them to the PC, where the information is stored and the processes are visualized on the HMI screen. During this study, the charging process was analyzed using PWM- and MPPT-type charging controllers, as well as the power supply of Fito LED strips for lighting plants. Using the created monitoring system, the parameters of the solar power plant with flexible PV modules were monitored. This study compared PWM and MPPT battery charging methods, finding that MPPT is more efficient, especially under unstable solar conditions. MPPT technology optimizes energy usage more efficiently, resulting in faster battery charging compared to PWM technology. MPPT controller; microcontroller; flexible PV modules; monitoring system +
Footnote †: journal: Applied sciences  
the development of renewable energy in the transport sector, reducing greenhouse gas emissions and dependence on fossil fuels. Various studies are currently underway to increase the efficiency and energy storage capacity of solar panels, which in the future could allow electric cars to use solar energy not only as an additional, but also as the main source of energy. Flexible solar modules can be fabricated using very thin Si sheets (between 1 and 10 \(\upmu\)m) [1; 2; 9; 10; 11; 12]. In the production of flexible solar modules, in order to reduce the use of silicon, various innovative materials are used, which are characterized by flexibility and efficiency in the light conversion process. The production of these modules is based on three main groups of components: active light conversion materials, electrodes and a flexible base. One of the key solutions in flexible solar modules is organic materials. Organic semiconductors, such as conjugated polymers or small molecules, are used to absorb light and convert it into electrical energy [1; 2; 3; 13; 14; 15; 16]. Polymers such as P3 HT (polythiophenes) and PCBM (fullerene derivatives) are commonly used to form the active layer. These materials are easy to combine and print and offer flexibility. Another alternative are perovskite-type materials, which form hybrid organic-inorganic semiconductors. These materials have extremely high photoelectron conversion efficiency and can be easily used in thin layers on flexible substrates. Perovskite photovoltaic cells are often made using combinations of organic and metal halides, such as methylammonium lead halide (MAPbX3), where X represents a halogen such as iodine or bromine. CIGS (compounds of copper, indium, gallium and selenium) are also used in flexible solar modules. This group of semiconductors is particularly efficient in the light absorption process and suitable for flexible surfaces [2; 17; 18; 19; 20; 21]. Due to their chemical composition, CIGS layers are easily integrated on polymeric or metallic flexible substrates. As an alternative to traditional electrodes, graphene and carbon nanotubes are used. Graphene, with its high conductivity and flexibility, can be used both as a conductive layer and as a protective top layer. Carbon nanotubes are also a good choice due to their mechanical strength and electrical conductivity. Since flexible modules must be light, durable and easily integrated into various structures, materials such as plastics, polyimides and metal foils are used. When using flexible solar modules in off-grid solar power plants, it is important to choose an efficient battery charging method. Two main methods are used for this: PWM (pulse-width modulation) and MPPT (Maximum Power Point Tracking) charging controllers [2; 3; 4; 20; 22; 23; 24].