## 1 Introduction
Voltage, current and power sensors are used to monitor the operating parameters of individual solar power batteries. Such type sensors can be attached to each module, so that in the case of a large solar park, the number of these modules and the amount of information they send are very large [11; 12; 13]. IoT technology is often used to ensure reliable information transmission and processing of these sensors. For using this technology and ensuring a stable data flow, a high internet speed, which can be provided by Wi-Fi or quality GSM mobile communication networks with 4G or 5G generation technology, is required. The greater the number of different sensors, the greater the need for a fast information transmission network. Many solar power parks are located outside the city limits in remote areas where it is not possible to provide a very fast internet connection provided by the GSM network [14; 15; 16; 17]. Therefore, in order to ensure a stable data transmission process, it is necessary to design a hybrid data transmission network using RF modules connected to each sensor and transmitting information to the central server. Meanwhile, the received information on the central server is analysed, stored and transmitted centrally to a remote data center using e.g., a GSM network if the solar park is built in a remote area. Data can be stored directly on a central-server-contained database (e.g., MySQL) or using cloud technology. Specialized software tools such as, e.g., SKADA, the Aix-layer detection algorithm or others, built and installed on the central server, perform data analysis and make appropriate decisions (e.g., send a message to the operator about a solar panel whose electrical parameters do not fall within the permitted range). Analysing the received information, the operator makes relevant decisions related to the operation of solar panels, such as sending a drone with a camera that would allow to evaluate the general image of a specific solar module or a brigade composed of qualified personnel able to eliminate the problems [18; 19; 20]. Ensuring a unified monitoring process for individual modules of a solar power plant or park is a difficult task, as it is necessary to simultaneously evaluate a large amount of information received from individual sensors or unmanned monitoring devices [21; 22; 23; 24]. When evaluating this information and making relevant decisions, it is impossible to avoid errors related to the human factor. Therefore, in order to avoid problems related to decision-making as much as possible, efforts are being made to create the most intelligent self-control systems that are as independent of human intervention as possible. In order to achieve this goal, various applications (software tools for mobile devices, etc.) are often developed that allow the operator to transmit information to the mobile device about an event that has occurred (e.g., a decision made by artificial intelligence related to the information sent by the sensors of the solar power plant, etc.) if the operator is not present in the stationary control panel. Software applications can be adapted to various mobile devices (e.g., smartphones or laptops) with operating systems such as Windows Phone OS, Android, etc. [24; 25; 26; 27; 28; 29; 30]. Following an analysis of the literature, it has become clear that there is no universal hybrid data transmission network concept for monitoring the working parameters of solar power parks. Meanwhile, solar parks are often built in remote areas where the speed of the external internet connection, which operates on the basis of the GSM network, is insufficient. In addition, in order to monitor the operating parameters of individual solar panels and conduct monitoring, a very dense IoT network is required, the speed of which may not be sufficient to ensure data transmission and communication between individual components.