Category: Journal Automatica and Informatics

Key Words: Artificial neural network; approximation; Laguerre functions.

Abstract. The present article examines a well-known procedure used in various scientific fields – approximation. Specifically, it analyzes the application of Laguerre orthonormal functions in the approximation of transient and impulse responses of dynamic systems. Particular attention is given to the challenges associated with using these functions in the context of model predictive control (MPC) synthesis. These challenges include determining the scaling factor, the number of orthonormal functions, and the calculation of decomposition coefficients, which create additional difficulties when modeling systems with parametric uncertainties. To overcome these challenges, the use of artificial neural networks (ANN) is proposed for the automatic generation of the decomposition coefficients of Laguerre functions. Instead of directly approximating the impulse responses of systems, which involves significant computational complexity, ANN is employed to predict the optimal decomposition coefficients, thereby reducing computational time and improving accuracy. As part of the study, simulations were conducted for the approximation of both low- and high-order systems with different levels of parametric uncertainty. The results demonstrate a significant improvement in approximation accuracy when using neural networks compared to standard coefficient computation methods. Graphical representations of the approximation results for different values of the scaling factor and the number of orthonormal functions are provided, analyzing their effects on approximation error. It has been established that, with proper training of neural networks, significant improvements in the approximation process can be achieved, making them suitable for implementation in real-time control systems. The proposed methodology extends the applicability of Laguerre functions in model predictive control and provides an efficient approach for handling systems with uncertainties.

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Key Words: Artificial Intelligence; integration; industrial automation; industrial control systems; Machine Learning; operational control; technological control.

Abstract. The newly emerging challenges of interpenetration and multifaceted integration of modern artificial intelligence technologies and leading computer systems of industrial automation are considered in the article. The relatively independent development of industrial automation and artificial intelligence has reached in the last one or two decades such a high technological level of openness, flexibility and compatibility, creating prerequisites to build integrated systems based on a holistic synthesis of a completely new type for solving tasks which until recently were considered intractable. The new conditions of competition are significantly complicated due to the extremely accelerated dynamics and depth of the various stages of industrial processes – supply chains, transportation problems, technological breakthroughs in the basic facilities and processes, malicious cyber attacks, situations resulting from global geopolitical conflicts. The main achievements that give rise to huge expectations for overcoming these and the expected future challenges are: the fundamentally new level of information treatment (Big Data), the modern achievements of computing technology (Industrial Internet of Things – IIoT, cloud technologies, computing architectures based on of graph models) and the explosive development of artificial intelligence (multidimensional and multi-aspect models, automatic prediction, decision-making and planning, revealing implicit relationships and dependencies, learning based on historical, current and simulation data, human-machine interaction of a new type ). Under the new highly complicated conditions and increased requirements, industrial automation is steadily following its trajectory of expanding its scope of action – from primarily technological control to gradually including all sides of the operational control and management (planning, production schedules, predictive maintenance of the facilities, adaptation to the goals and situations in the short and long term). The realistic approach requires strategic decisions in the development of industrial automation to be in the direction of „end-to-end automation“ by upgrading existing systems while uncompromisingly evaluating the advantages and disadvantages of the relevant artificial intelligence technologies that we have now.

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Key Words: Calculation of energy; wood containing ice; melting frozen water; thermal treatment; Table Curve 2D.

Abstract. A mathematical description of the thermal energy consumption Qice required to melt the ice formed in the wood by the natural freezing of both free and bound water in it, using the software package Table Curve 2D v.5.01 has been presented. This package allows for the selection of equations, which provide the best similarity between the calculated with them values of Qice during thermal treatment of wood containing ice and the respective numerical data obtained experimentally or using an adequate temperature-energy model of Qice. For the determination of Qice, the classical approach from thermodynamics was used to calculate the energy required to heat a solid body from any initial temperature to a certain final temperature. In our case, the energy Qice is represented as a sum of the energy Qice-bw required to melt the initial temperature-dependent frozen portion of the bound water in the wood, and the energy Qice-fw required to melt the ice formed by freezing all the free water in the wood. The energies Qice-bw and Qice-fw are represented as a product of the ice density with the specific heat capacities of the frozen bound and free water in the wood and the temperature ranges in which the melting of the two types of frozen water takes place. Mathematical descriptions of the specific heat capacities of frozen bound and free water in wood are also presented, taking into account the latent heat of the phase transition of water. The calculations of the energies Qice-bw, Qice-fw, and their sum Qice were made for the case of thermal treatment of frozen beech wood with an initial temperature of −1 °C, −10 °C, −20 °C, −30 °C, −40 °C and moisture content of 0.4 kg·kg-1, 0.6 kg·kg-1, and 0.8 kg·kg-1. The obtained results were processed using the Table Curve 2D software package. Three logarithmic equations of the same type were selected, which mathematically describe the dependence of Qice on the initial temperature of the frozen wood for each of the investigated values of its moisture content. It was found that there is a very small error (within the limits of only 3.5%) between the equations calculated with Table Curve and the approximate values of the Qice. The equations obtained can be used for development and automatic implementation of scientifically based energy-efficient regimes and technologies for steaming or boiling of frozen wood materials with different properties and purposes.

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Key Words: Human-Computer Interaction; smart home systems; security; human-computer interface.

Abstract. Human-Computer Interaction (HCI) is a critical field of study that has gained increasing importance over time. Today, smart home systems are among the most common application areas of human-computer interaction. These systems offer efficiency and end-to-end connectivity to users. Moreover, IoT frameworks and other technological integrations are widespread and indispensable components of these systems. However, significant security concerns and vulnerabilities associated with these systems are also on the rise. This study examines the relationship between HCI and smart home systems, focusing on the requirements for intuitive and secure interface designs. The research highlights the need for the convergence of HCI interface designs with smart home systems, emphasizing the necessity for continuous innovation and improved security mechanisms. It also underscores that future advancements in cutting-edge technologies, such as artificial intelligence, 5G/6G, blockchain, and quantum computing, are expected to present both opportunities and challenges to the design and operation of smart home systems. In conclusion, as interactions between humans, advanced technologies, and smart systems become more frequent, the application of HCI principles in the design of smart home systems will become increasingly crucial. Ensuring that these systems are not only usable but also secure is vital, making them safe and accessible for users with low digital literacy. Integrating both technical and human-centered perspectives in the holistic development of these systems is imperative.

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Key Words: Predictive diagnostics; competitiveness; costs; innovation.

Abstract. In today’s highly competitive economic environment, effective predictive maintenance of equipment is critical to ensuring high productivity, product quality, on-time delivery and a safe work environment. Predictive maintenance itself is a well-established approach that uses equipment condition data to predict and project future operating conditions leading to system-wide improvements. Having an integrated, computer-based information management system is a strong competitive advantage over today’s complex manufacturing systems. To automate and optimize these processes, advanced systems including Internet of Things (IoT) modules are often used, which enable intelligent devices to exchange information with each other and with others via the Internet, creating a large-scale network of interconnected devices. Such connectivity helps in cost accounting, production and maintenance planning, environmental compliance data, etc. A successfully implemented system will provide an opportunity for effective communication and coordination of predictive maintenance activities leading to continuous improvements of key indicators.

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Key Words: Pregnancy monitoring; IoT; health tracking; pulse oximetry; heart rate monitoring.

Abstract. Monitoring the health of pregnant women is essential for promoting a safe and successful pregnancy. This paper presents the development of a monitoring system using the ESP32 microcontroller, along with the MAX30205, MAX30100, and BME680 sensors. The ESP32 acts as the core unit for data collection and transmission. The MAX30205 sensor provides precise real-time temperature readings, while the BME680 measures key environmental factors such as humidity, pressure, and gas resistance. Additionally, the MAX30100 monitors pulse rate and blood oxygen levels. Together, these sensors enable comprehensive health monitoring for pregnant women.

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Key Words: Remote measurement; data transmition; public net communication; WiFi Internet; data base management; web site.

Abstract. Тhe system, described in the article for measurement and remote transmission of data from measuring devices such as water meters, electricity meters and others, contains the following components: periodic measurement, remote transmission of measured data, storing the data in a centralized database server, displaying the current data in tables and graphs, display history of measurements based on stored data in DB. The transmission of the measured data is realized in the following communication media: public networks (A1, Vivacom, Yettel), Internet network.

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Key Words: Cryptographic; hash-function; comparative analysis; MDC MAC; collision resistance; Message Digest.

Abstract. The paper presents the fundamental role of hash functions in modern cryptography and Network security. To control the integrity of stored or exchanged data, cryptographic hash functions, also called OWHF (OWHF – One Way Hash Functions), are most often used. These functions are not used to protect the data, but to verify its identity.Hash Functions compresses a message of arbitrary length to a message of fixed length called hashcode or Message Digest (MD). According to the purpose they serve, there are two main types of hash functions – MDC and MAC. Keyed hash functions use secret key for computing the digest and these are also known as MAC (Message Authentication Code). The purpose of MAC is to authenticate the data source. MDC (Message Detection Codes) are un-keyed functions and serve to authenticate the data integrity. The three distinctive properties of hash functions are discussed: 1. Preimage resistance – for essentially all pre-specified outputs, it is computationally infeasible to find any input which hashes to that output. 2. 2nd-preimage resistance – it is computationally infeasible to find any second input which has the same output as any specified input. 3. Collision resistance – it is computationally infeasible to find any two distanct inputs whish result to the same output. Defined the fields of application of the hash functions: 1. Data integrity check when exchanging data (file, string, database, etc.). 2. Storing access passwords on sites. 3. Digital signature. 4. Search for identical files and match of data. This paper presents a comparative analysys of hash functions that are curentlu used. The most frequently used functions (MD, SHA, WHIRLPOOL, RIPEMD, MASH-2 etc.) are presented in tabular form. A comparison was made according to some basic characteristics: input message size, output value, conversion method, logical operations used, operations used, etc. On this basis, can be made a decision to use a particular hash function for one purpose or another, according to the specific requirements for input message dimensionality, speed, and degree of security.

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Key Words: Personalized learning; intelligent systems; collaborative approach.

Abstract. The problems of searching for a rational solution in the design and operation of modern intelligent systems for personalized engineering training are considered. Emerging favorable opportunities and implementation risks are analyzed in three main aspects – pedagogical strategies, technological efficiency and system coordination. The existing research and practical experience is insufficient to make informed decisions, especially in the conditions of extremely rapid development of technologies based on artificial intelligence, which are of key importance for personalized learning systems. Given the great complexity of personalized learning systems, only a collaborative approach of teams including researchers, educators, and artificial intelligence specialists would be successful in finding balanced rational solutions.

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Key Words: Logs; frozen bound water; frozen free water; thermal treatment; plasticizing; energy consumption; veneer production.

Abstract. An approach for computing the energy required for warming up and plasticizing of frozen logs subjected to thermal treatment in the production of veneer has been presented. The approach is based on the use of two personal models. With the help of the non-stationary model, the thermal treatment times of beech logs with a diameter of 0.4 m, initial temperatures of –1 °C, –10 °C, –20 °C, –30 °C and moisture content u of 0.4 kg∙kg-1, 0.6 kg∙kg-1, and 0.8 kg∙kg-1 were determined at operating temperatures in the boiling or steaming equipment equal to 80 °C. For different combination of the three values of moisture content and four values of the initial log temperature there are significant differences between the amount of both free and bound frozen water in the logs, which ensures sufficiently large differences between the calculated values of the energy consumption of the logs. Furthermore, the logs with initial temperature of –1 °C contain only frozen free water and no frozen bound water at all. Using the determined logs’ thermal treatment durations, with the help of our second model the change in the energy required for warming up and plasticizing of the investigated logs and that for each of its 4 components was calculated. It was found that the studied energy increases from 55.3 to 67.2 kWh∙m-3 at u = 0.4 kg∙kg-1, from 75.9 to 89.1 kWh∙m-3 at u = 0.6 kg∙kg-1 and from 94.6 to 108.8 kWh∙m-3 at u = 0.8 kg∙kg-1 when the initial temperature of the logs decreases from –10 °C to –30 °C. At initial log temperature of –1 °C the energy required for plastcizing of the wood changes from 46.0 kWh∙m-3 at u = 0.4 kg∙kg-1 to 84.9 kWh∙m-3 at u = 0.8 kg∙kg-1. Four types of individual components of the considered energy have been calculated, namely: for warming um of the frozen and non-frozen wood itself, for melting of the temperature dependent frozen part of bound water, and for melting all
frozen free water in the logs.

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Key Words: Discrete state controller; objects with a delay; state observer; Smith predictor systemр Pade series.

Abstract. The control is a purposeful impact on the object of control, as a result of which it is brought to a desired state, which is determined by the requirements of the technological process. The main requirement is that this process is sustainable, but this is not enough. There are also certain requirements regarding the quality of the processes that take place in the system – quick action when working out disturbing effects or when changing the mode of operation, permissible deviations from the established mode, amplitude limitations of the controlling effects, etc. Often the requirements for the managed process are mutually contradictory and it is necessary to seek a reasonable compromise between them. It is accepted, when the feedback in a control system is carried out by means of the state vector, the controller in this system is called a State Controller (SC). If the state x(k) can be measured directly at every moment k=0, 1, 2, … we speak of control in the presence of complete information. When the state cannot be measured directly, but is estimated by other quantities that are related to it and available for measurement, it is said to be control with incomplete information. The delay in the object of control, whatever its nature, its presence creates difficulties in the implementation of the control system, worsening the quality indicators of the ongoing processes. When using a discrete state controller to control objects with a delay, in order to be able to synthesize the state observer it is necessary to represent the delay unit with a fractional-rational function using a Pade series. This enables the object of control to be represented as a higher-order object without delay, but leads to a significant extension of the transition process in the system.

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Key Words: Switched Reluctance Motor; rotor position; motor torque; co-energy; JMAG-Express software.

Abstract. Due to the development of electronics and control methods, interest in Switched Reluctance Motor (SRM) is returning and today they are being studied by many scientists around the world. This article discusses the torque determination of a Switched Reluctance Motor (SRM) using co-energy. Described is conversion of electrical energy into magnetic field energy and mechanical energy. In these electric machines, the electromagnetic moment is defined as the change in electromagnetic energy due to the change on the angular position of the rotor. The purpose of the study is to find the parameters on which the torque depends in order to form an appropriate control strategy. To simplify the analysis, it is assumed that the machine remains in an unsaturated state during operation – magnetic saturation is neglected, the inductance of the motor depends only on the rotor angle. An exemplary variation of the inductance from the rotor position is shown, which is a direct consequence of the variation of the total magnetic flux and current in the energized phase winding. The areas of operation of SRM are described. Also shown is an exemplary mechanical characteristic of the SRM where the constant torque, constant power, and decelerating power sections are described for low, medium, and high engine speeds. The structure and control principles of the SRM determine the drive characteristics. The basic control strategy involves successive switching of phases at well-defined moments of time. For accurate control it is necessary to account for the highly nonlinear inductance problems and the following ripples of electromagnetic moment. SRM modeling aims to accurately establish the relationship between magnetic flux, torque, current and rotor position, which will contribute to accurate analysis and precise control of these motors. The simulation of SRM 6/4 was made using JMAG-Express software.

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Key Words: Efficiency; energy; social marketing; municipal utility clusters; market with freely negotiated prices.

Abstract. The sale of electricity, heat and natural gas in Bulgaria is characterised by an almost 100% monopoly at regional level. These supplies are licensed on a territorial basis and do not allow local competition. There is a lack of symbiosis between centralised energy and the established regional power plants (mainly PV power stations). This is a serious obstacle to the deployment of RES and the Green Transition that Bulgaria needs. The article discusses the legal framework and proposes an organization at local level for the creation of operating structures – utility clusters for the integration and balancing of energy flows, including those from RES. The regulatory base in Bulgaria allows the creation of such structures in the country. This would solve a number of problems – social, demographic, environmental and purely economic. It is a matter of proper organisation that the energies from these sources are cleverly managed, integrated and balanced as close to the consumer as possible.

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Key Words: Damask rose; drying speed; humidity, energy.

Abstract. The article presents the results of a study of the duration of drying under atmospheric conditions of residual plant biomass generated during the annual contour pruning of the oil rose bushes. The contour pruning of the bushes was done after the completion of the rose bush. The cut biomass is rented from the inter-rows of the arrays. Results of an additional study of this biomass from the same massif stored in bundles in a closed, ventilated warehouse until the end of October are presented. The periods for reaching an air-dry state with a moisture content of 14.38% and below 10% have been determined. Based on the obtained results, a recommendation was made for the use of naturally dried plant biomass. In this way, there is no need for expensive equipment and energy to dry it and bring it into a suitable form for further processing and use.

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Key Words: Academic research; technology transfer; validation and technology transfer; validation steps and tools.
Abstract. This thematic summary is based on publications of the Industry Committee of the International Federation of Automatic Control (IFAC), T. Samad et al., Industry engagement with control research: Perspective and messages, Annual Reviews in Control, vol. 49, pp. 1–14, 2020 and IEEE Control Systems Society: Control for Societal-Scale Challenges: Road Map 2030, published May 2023. The main goal of both developments is to bridge the gap between academia and industry. Based on IFAC Industry Committee discussions, surveys and research, 10 messages to the research community have been formulated. The road from academic research to industrial incorporation is difficult and lengthy. It is argued that the lack of validation is a major obstacle to the transfer of technologies developed as a result of academic research, and in practice the academic community can play a crucial role in the validation process. Five steps in validation and tools for each step are identified, and recommendations are presented to advance validation and facilitate the transition to innovation and technology transfer in the short, medium and long term.

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Key Words: 3D reconstruction; Structure From Motion (SFM); Image segmentation; Robotics.
Abstract. The technique of 3D reconstruction of real scenes from images represents a significant advancement in visual technologies, offering the potential for the development of numerous new applications in various engineering fields. In general, 3D reconstruction from images is a computer process that utilizes a set of two-dimensional images captured from different angles and positions to create a three-dimensional model of the scene or object. By analyzing features such as key points, comparing their positions, and applying geometric principles, this process transforms the images into three-dimensional representations with spatial information. The complexity of 3D scene reconstruction from images arises from the need to detect points of interest, match and track them across different images, as well as analyze and merge multiple visual data from different perspectives. This article proposes the use of simpler image processing algorithms to obtain more points of interest, providing a more accurate 3D model without overburdening the reconstruction process with complex computational procedures. The investigated methods implement image segmentation through the first and second derivatives of the image intensity function to determine and separate edges and boundaries in the image. A practical implementation of 3D reconstruction of real scenes from images in the Matlab environment is presented. In the implementation, algorithms based on the first and second derivatives of the image intensity function are used to achieve a denser 3D model by segmenting images to detect edges and boundaries. The investigated algorithms are implemented in the stage of discovering properties in the image. Some of the most well-known algorithms have been tested and compared with the use of the standard SURF algorithm. The algorithms from this class have significantly improved results, with the density of the 3D model increased several times compared to the number of generated points, and in some cases, the execution time remains the same relative to the percentage ratio of the generated 3D points.

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Key Words: Education; sciences; IP; technology transfer; technology commercialization.
Abstract. The article studies a training model that includes the development, planning, organization, and implementation of training on the topic “Technology transfer and commercialization of technologies” at University of Chemical Technology and Metallurgy (UCTM). The purpose of the article is to present the process and content of the training conducted with the support of the BiOrgaMCT project. The article also includes and discusses the learning outcomes and plans for future development of technology transfer and commercialization of scientific research at UCTM. The following concepts were awarded as projects with serious opportunities for technology transfer and commercialization: Development of advanced materials and technical ceramics for special purposes, Clean technologies and utilization of waste from plant raw materials and wastewater, Development of biologically active molecules for multi-target therapies and Creation of a new, regenerative material from used textiles for cleaning up oil pollution.The lesson learned is that the course was very useful, both in relation to the realization of the project on which it was organized, and in view of the future development of the university as a research institution. That is why we believe that similar education can be successfully implemented in other higher education institutions in Bulgaria.

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Key Words: Reusable identity; decentralized identity; self-sovereign identity; web3 identity; zero-knowledge proofs; trust models.
Abstract. The trajectory of decentralized identity, anchored in the principles of self-sovereign identity (SSI), Decentralized Identifiers (DIDs), and verifiable credentials, holds the potential to redefine the contours of the digital landscape. This paradigm shift not only signifies a pivotal transformation but also heralds the advent of an epoch characterized by heightened trust, enhanced privacy, and fortified security. This article presents the major scientific developments and applications of 2023 in the field of Decentralized Identity. Decentralized identity (DID) continues to witness significant progress, with 2023 shaping up as a year of noteworthy scientific advancements and impactful applications. This article delves into the major developments that have propelled the field forward. Firstly, we explore the evolution of DID specifications and standards. We examine the progress of ongoing initiatives like the W3C DID Working Group and the Hyperledger Aries framework, highlighting their contributions to interoperability and secure identity management. Secondly, we review the existing publications on the subject and categorize them based on the nature and focus of the research. This classification scheme provides a framework for understanding the diverse facets of scientific research on Decentralized Identity. It highlights the multidisciplinary nature of SSI research, which spans computer science, cryptography, engineering, etc. Another approach we took in the classification of the scientific publications on SSI, especially the more technologically focused studies, was based on the working groups, operating within the DIF. Thirdly, we delve into the security and privacy advancements in 2023. This section explores novel research on zero-knowledge proofs for DID systems, privacy-preserving credential issuance, and techniques for mitigating security vulnerabilities. Furthermore, the article examines the social and economic impacts of DID implementations. We analyze case studies and emerging applications across various sectors like healthcare, supply chain management, and education, highlighting how DID is transforming trust models and empowering individuals. Finally, we discuss the challenges and future directions for the field. This section considers the need for scalability, regulatory frameworks, and broader adoption to unlock the full potential of DID. By synthesizing these key aspects, this article provides a comprehensive overview of the current state of DID, showcasing its scientific advancements and diverse applications in 2023. It aims to inform researchers, practitioners, and policymakers about the transformative potential of DID and the ongoing efforts to shape a more secure and user-centric future for digital identity management.

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Кey Words: Concrete pits; non-frozen logs; boiling; energy consumption; energy efficiency; veneer production.

Abstract. An approach for computing the energy consumption and energy efficiency of pits during boiling of non-frozen logs intended for veneer production has been presented. The approach is based on the use of two personal mathematical models: 1D non-linear model of the unsteady distribution of the temperature along the radius in the central cross section of non-frozen logs subjected to boiling at conductive boundary conditions, and model of the thermal balance of concrete pits during boiling of wood materials in them. For numerical solving of the models and practical application of the suggested approach, a software packages were prepared in the calculation environment of Visual FORTRAN Professional and in Excel respectively. With the help of the first model, the boiling times of beech logs with a diameter of 0.4 m, initial temperature of 0, 10, and 20 °C and moisture content of 0.6 kg∙kg-1 were determined at water temperatures in the pit equal to 70, 80, and 90 °C. Using the determined logs’ boiling durations, with the help of the second model the change in energy required for the entire boiling process and that for each of the components of the thermal balance was calculated. Computer simulations were performed for a well-insulated concrete pit with working volume of 20 m3 and degree of filling it with logs 45%, 60%, and 75%. It was found that the energy consumption of the pit decreases from 159.7 to 145.3 kWh·m-3 when the initial temperature of the logs increases from 0 °C to 20 °C at temperature of the boiling water of 80 °C and maximum possible degree of feeling of 75%. In this case, the thermal efficiency of the pit decreases from 32.2% to 26.1%. It was found also that at the same degree of feeling of the pit the increase in the boiling water temperature from 70 °C to 90 °C causes an increase in the energy consumption of the pit from 135.3 to 170.9 kWh·m-3 when the initial temperature of the logs is equal to 10 °C. Under these conditions the thermal efficiency of the pit decreases from 29.9% to 28.8%. The approach can be applied to compute the energy consumption and thermal balances of concrete pits during boiling of non-frozen logs to any desired final average mass temperature required for the mechanical processing of the plasticized wood. It could be easily modified and used to calculate the energy consumption and efficiency of concrete pits of any design and construction parameters.

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Key Words: Photovoltaic systems; solar power generation; educational institutions; design engineering; energy management.

Abstract. The solar modules that are produced have a rather fragile structure and must therefore be mechanically protected on both sides. For this purpose, a so-called sandwich structure is used, in which the photovoltaics are placed on a solid base and covered with a transparent upper protective layer. The coefficient of thermal expansion of the materials of the upper and lower protective layers must be the same and, moreover, comparable to that of the photovoltaic cell and the bonding resin used. Currently, the most widely used materials are glass and plastic. Photocells sealed under glass have the advantage that they do not change their optical, mechanical and electrical properties during prolonged outdoor operation. Polymers cannot prevent the penetration of moisture, so they are only suitable when the photovoltaics and metal contacts are protected by an anti-corrosion coating. Plastics are lighter than glass, but they have the effect of aging with prolonged exposure to atmospheric conditions, which strongly affects their qualities. The upper transparent protective layer allows easy cleaning of the solar cells, but during their installation, they must be placed in such a way as to avoid their heavy contamination and the retention of snow on them. This is practically achieved by the southern orientation of the panels and their placement at an angle corresponding to the latitude of the site, as well as taking into account the season of operation. Some panels are oriented to the southwest so that they can produce the necessary energy for the afternoon maximum. For most locations, a slope angle close to horizontal will provide the most energy year-round. The cells used today have an efficiency of 3-20% in converting solar energy into electricity. A photovoltaic generator is a set of modules that convert solar energy into direct current (DC) electricity. It consists of a module formed by several photovoltaic cells, connecting several such modules form a panel, and several panels connected together form an array. Connecting several arrays electrically in parallel forms a photovoltaic generator or photovoltaic park. By connecting a certain number of photovoltaic cells in parallel and in series, any desired power can be obtained. The main element of the photovoltaic generator is the photovoltaic cell, where the conversion of solar radiation into flowing electric current takes place. The present work presents a practical task of a photovoltaic energy system for a public educational building. The purpose of the case study is to provide technical measures to improve the energy efficiency of the building, according to the technical specification and the current regulations. Public school buildings are mainly used during the daylight hours, where solar energy will be used for self-consumption.

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