The aim of the work is to study the optical properties of CdTe semiconductor films obtained by electrochemical deposition. The relationship between the electrophysical characteristics of the formed CdTe films and the electrolysis parameters was established. For this purpose, the most appropriate composition of the electrolyte for obtaining CdTe films was determined. A basic technological scheme of the process of obtaining electrochemical formation of semiconductor optically active CdTe films was developed, and the technological modes of individual stages were determined. The kinetic parameters of electrochemical reactions were determined by the method of voltammetry. The analysis of electrolytes for the content of components was determined by titrometric and weight methods. The morphology of the resulting precipitates was studied by optical microscopy. Optical parameters of the obtained experimental samples were studied by the optical spectrophotometric method. Band gap, refractive index, static and high-frequency dielectric constants of deposited CdTe films were calculated by the analytical processing of experimental data.

Thin films of cadmium telluride (CdTe) with metastable hexagonal structure were deposited by DC magnetron sputtering on glass substrates and subsequently subjected to CdCl2-mediated chloride treatment followed by thermal annealing at ~400 °C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed to investigate the chloride treatment’s impact on film microstructure and microstrain. The crystallite size, calculated using Scherrer’s formula, increased by approximately 40% after treatment, indicative of recrystallization, a result corroborated by size-strain plot (SSP) fitting. Williamson-Hall analysis under UDM, USDM, and UDEDM models revealed significant reductions in microstrain (from ~0.00З1 to ~0.0007), mechanical stress (from ~0.20 GPa to ≈0.002 GPa), and strain energy density (~3136 to ~17kJ/m3), demonstrating defect passivation and improved structural ordering. SEM imaging confirmed enhanced grain coalescence and surface uniformity. Our findings align with established reports on CdCl2-driven recrystallization and defect passivation in CdTe thin films. The chloride treatment thus proves effective in optimizing crystallographic and mechanical properties of CdTe films, with implications for improved performance in photovoltaic and electronic applications.

This paper presents an overview of features of regulation of blocks of modulated voltage source inverters (VSINs) and neutral-point-clamped inverters (NPCIs) of photovoltaic (PV) installations in the overmodulation control region of inverters, regulated according to a strategy of synchronous space-vector PWM (SSV PWM), providing voltage synchronization and voltage symmetry of the corresponding installlations. Two-stage overmodulation control of inverters in this case is founded on modified control correlations, which include specialized correcting indices for the each stage of the over-modulation control zone. Specific overmodulation-focused algorithms of SSV PWM of inverters have been applied and observed for some structures of grid-tied PV stations: a) PV systems with two two-level inverters; b) dual-inverter PV systems with special scheme of connection of windings of the transformer, and c) two alternative topologies of PV stations based on three modulated inverters.

During the last years the design and implementation of energy-saving solutions remains a relevant and integral task for implementation the route of decreasing carbon emissions and reduce the negative impact on the environment. Using combined photovoltaic/thermal systems is limited by their high price connected mainly with the complexity of their control systems, even taking into account availability of government programs for financial support for the use of alternative energy. The novelty of the proposed work consists in the development of a mathematical model and the analytical study of the control system of combined photovoltaic/thermal system for research the operation of control and logic elements and their response to transient and emergency modes during such systems operation. Aim of the work - operational analysis, analytical and optimization studies of the control system of the combined photovoltaic/thermal system to ensure reliable operation in transient and emergency modes and significantly simplify the design of such a system. In this article was implemented mathematical modeling methods and using specialized software. As a result of the work the mathematical model of the control system of combined photovoltaic/thermal system which operates with variable set of control and logic elements was developed. A structural solution of the control system is proposed for further implementation and field testing. The response criteria of the control system to transient and emergency operation modes of the combined photovoltaic/thermal system have been developed. Practical value. It was established the permissible and critical values of a number of parameters characterizing the operation of combined photovoltaic/thermal system in normal mode and deviations from which indicate the presence of an emergency situation are determined. The proposed algorithms of the control system will make it possible to increase the reliability of combined photovoltaic/thermal system and reduce the risk of emergency situations during field tests and further operation.

Experimental study of energy and spectrum features and operational regimes was provided for a measurement stand with light emitting diodes based Sunbrick solar simulator. Capabilities of the presented stand ensures the practically fully automatization of measurement process for illuminated current-voltages characteristics of test samples of solar cells. Presented device is capable to simulate various regimes of solar radiation in the wide range of their energy and spectrum characteristics, including standart for photovoltaic industry spectrums like AM0, AM1.5, AM 1.5G. As a result of series of experiments was studied the main parameters of complex like stability of light beam, spatial unevenness from area of investigated solar cells, possibilities of manual and automatic control the spectrum components of illumination.

Мета роботи. Провести розрахунок енергетичного балансу фотоенергетичної установки для роботи в умовах концентрованого сонячного випромінювання, розробити конструкцію теплообмінного блоку з «мікро» каналами. Методи дослідження. Аналітичні дослідження за допомогою критеріальних рівнянь гідродинаміки, створення та дослідження комп’ютерних моделей на основі рівнянь теплового балансу. Отримані результати. На основі аналізу теплових процесів запропоновано конструкцію теплообмінного блоку оснащеного «мікро каналами» для комбінованої фотоенергетичної установки, що розрахована на роботу в умовах концентрованого сонячного випромінювання. Показано, що в такій конструкції створюється перехідний режим потоку рідини, що охолоджує, що дозволяє ефективно охолоджувати сонячні елементи в умовах концентрованого сонячного випромінювання. На основі результатів досліджень запропоновано шляхи покращення конструкції теплообмінного блоку для оснащення фотоенергетичної установки, розрахованої на роботу в умовах порушення типової енергоінфраструктури. Показано, що для зменшення перепаду температури за площею СЕ можливе перенесення входу теплоносія в центр і двох виходів на протилежних краях блоку. Наукова новизна. Вперше запропонована конструкція радіатора теплообмінного блоку на основі «мікроканалів», що забезпечує перехідний режим потоку з коефіцієнтом теплообміну між теплоносієм та верхньою пластиною радіатора hf ~ 10000 Вт/(м2⋅К) при швидкості потоку у проміжках між пластинами ~2.1 м/с. Практична цінність. Виконано оцінку ефективності, теплових та електричних характеристик комбінованої фотоенергетичної установки з концентрацією сонячного випромінювання. Запропоновано використання розробленої конструкції теплообмінного блоку для оснащення фотоенергетичної установки для роботи в умовах порушення типової енергоінфраструктури. Проведено попередній розрахунок теплових та електричних параметрів фотоенергетичної установки, оснащеної багатокаскадними сонячними елементами на основі арсеніду галію та теплообмінним блоком із «мікроканалами».

Thin film samples of cadmium telluride were obtained using thermal vacuum evaporation to study the diffusion length of minority charge carriers. Initial state analysis was conducted through X-ray structural studies of cadmium telluride condensed on glass substrates. The analysis revealed two diffraction reflections corresponding to the crystallographic planes (111) and (333). Calculations showed that the sizes of coherent scattering regions were 93 nm and 56 nm, while microstrain values were determined as 11.6×10−3 and 4.8×10−3, respectively, for these planes. Electron diffraction studies identified the zone axis of the formed film structures as [110]. Additionally, twinning and forming a layered substructure within the cadmium telluride thin films were observed. Microscopic surface studies provided insights into the surface relief, measured at approximately 130 nm, and the polycrystalline grain size, determined to be 1 micrometer. The method of spectral dependence of small-signal surface photovoltage was employed to investigate the electrophysical properties of cadmium telluride thin films. The diffusion length of minority charge carriers was calculated to be 0.45 micrometers, which is half the size of the grain dimensions. Furthermore, the transmittance coefficient of cadmium telluride was examined in the wavelength range of 800–900 nm. The optical bandgap energy was 1.4 eV, slightly lower than the 1.5 eV observed for monocrystalline cadmium telluride. In conclusion, cadmium telluride film structures produced by thermal vacuum evaporation exhibit electrophysical and electrical parameters inferior to monocrystalline cadmium telluride. These characteristics, particularly the low diffusion length of minority carriers and short electrical signal decay times make such film structures suitable for use in devices requiring long-term stability under the influence of time, extreme temperatures, electric fields, and radiation.

Using modernized vacuum systems, it has been prepared a series of CdTe thin film samples by application of thermal vacuum evaporation method on three types of substrate material in order to investigate the varying of thin films structural parameters in dependence of material of substrate. The structural parameters were investigated by using the method of X-ray diffractometric analysis, based on which the lattice parameters, the sizes of the coherent scattering regions and the texture coefficient of the samples were obtained. According to the experimental study it was found that for samples obtained on dielectric substrate only the cubic phase of CdTe was spotted. In case of samples prepared on substrate with conductive layer it was spotted the two types of hexagonal phases and a presence a little quantity of cubic phase. Samples prepared on metal substrate contains practically only from the cubic phase of CdTe which can be connected with technological regimes of film samples obtaining. For this samples were spotted the value of lattice parameter which maximally close to the etalon value among all investigated samples which is also mainly connected with technological features, especially the speed of thin film growth.

Purpose. Calculate the energy balance of a photo-energy installation for operation in conditions of concentrated solar radiation, develop the design of a heat exchange unit with "micro" channels. Methodology. Analytical studies using criterion equations of hydrodynamics, creation and study of computer models based on heat balance equations. Findings. Based on the analysis of thermal processes, the design of a heat exchange unit equipped with "micro channels" for a combined photoelectric plant designed to work in conditions of concentrated solar radiation is proposed. It is shown that such a design creates a transitional mode of cooling liquid flow, which allows for efficient cooling of solar cells under conditions of concentrated solar radiation. Based on the results of research, ways of improving the design of the heat exchange unit for equipping a photoelectric system designed to work in conditions of disruption of the typical energy infrastructure are proposed. It has been shown that in order to reduce the temperature difference over the SC area, the design of the heat exchange block can be optimized by moving the coolant inlet to the center and creating two exits at the opposite ends of the block. Originality. For the first time, the design of the radiator of the heat exchange unit based on "micro-channels" was proposed, which provides a transitional mode of coolant flow with a heat exchange coefficient between the coolant and the upper plate of the radiator. hf ~ 10000 W/(m2K) at a flow speed in the gaps between the plates ~2.1 m/s. Practical value. The evaluation of the efficiency, thermal and electrical characteristics of the combined photo-energy system with the concentration of solar radiation was performed. It is proposed to use the developed design of the heat exchange unit for equipping a photoelectric plant for operation in conditions of disruption of the typical energy infrastructure. A preliminary calculation of the thermal and electrical parameters of a photovoltaic installation equipped with multi-cascade solar cells based on gallium arsenide and a heat exchange unit with "microchannels" was carried out.

Young's modulus (E) and Poisson's ratio ($v$) are critical for the theoretical calculation and experimental determination of residual stresses that occur during the growth of semiconductor thin films. This paper introduces generalized expressions for E, v and $E/(1-v)$) for hexagonal and cubic structures common to cadmium sulphide and cadmium telluride semiconductors. These elastic constants are found to be invariant within the c-plane. Numerical values for these constants have been computed and tabulated for CdS and CdTe.

In recent years, the production of solar cells (SC) based on crystalline silicon has become cheaper and at the same time increased, thanks to which solar panels from the predominantly energy source of spacecraft have become a recognized energy resource with an installed capacity of 680 GW and maintains the highest growth rate.

The paper introduces the concept of a photoenergy system based on film photovoltaic converters using the CdS/CdTe heterosystem. The goal is to develop a design solution for a flexible thin-film photovoltaic converter system that can be directly mounted on a heat collector plate, integrating photovoltaic converters with thermal collector systems. The paper highlights the limitations of traditional silicon-based photovoltaic converters and propose using flexible photovoltaic converters based on CdS/CdTe, which have concentrated absorption within the visible range and allow unobstructed flow of long-wave solar radiation for efficient thermal energy generation. The paper discusses the methods of obtaining samples of flexible photovoltaic converter ITO/CdS/CdTe/Cu/Au solar cells, including the deposition of layers on polyimide films, chloride treatment, and annealing processes. Analysed the impact of the “chloride” treatment on the structural and optical characteristics of the base layers and present the overall appearance of the thin-film photovoltaic converter samples. The structural analysis of the cadmium telluride films is conducted using X-ray diffractometry techniques, while the optical properties are investigated using a spectrophotometer. The light-voltage characteristics of the photovoltaic converter samples are measured under illumination conditions, and various output parameters and characteristics of the photovoltaic converter are determined. The authors emphasize the significance of optimizing the performance of the cadmium telluride layer in the flexible photovoltaic converter structure and discuss the variation of technological parameters to enhance efficiency. Paper presents the output parameters and light diode characteristics corresponding to different thickness ranges of the CdS layer. Overall, this paper provides valuable insights into the development of flexible film photovoltaic converters based on the CdS/CdTe heterosystem for integrated photovoltaic and thermal collector systems. The experimental methods and results contribute to the understanding of optimizing the performance of the photovoltaic converters and offer potential applications for autonomous heat supply systems.

This paper briefly reviews the development and widespread use of an alternative method of synchronous pulse-width modulation (PWM), based on a space vector approach, for the control of voltage source inverters (VSIs) and inverter-based photovoltaic grid-tied (PV) installations with low switching frequency of inverters. It assures providing synchronization and symmetry of winding voltage of power transformer for any operation conditions including cases of fluctuation of grid frequency, of unequal voltages of dc-sources (PV panels), etc. Examples of the use of this PWM method to control several topologies of VSI-based photovoltaic stations with multi-winding power transformer are presented.

This research delves into challenges facing efficient cadmium telluride (CdTe) thin-film photovoltaic converters and proposes solutions. It suggests using micro and nanomodules, coupled with hybrid thermal photo energy systems, to improve CdTe converter performance and reduce costs. Experimental PVC/CdS/CdTe/Cu/Au converters are analyzed, comparing parallel and serial connections for better performance. The article also discusses rear film electrode geometry’s impact on micro and nanomodule performance.

Commissioning and experimental testing of technical capabilities and modes of operation were carried out, and test measurements of light current-voltage characteristics of solar cells were carried out using a modern measuring complex based on the Sunbrick sun simulator. Automated measurement of the light-voltage-current characteristics of solar cells by the compensation method using the Keithley 2400 measuring device was implemented. During the approbation of the measuring complex based on the Sunbrick sun simulator, the possibility of reproducing different modes of simulator operation was tested and the ability to control radiation in terms of energy in the range from 100 to 1100 W/m2 and by spectral composition. It was established that the spatial unevenness of illumination for the investigated device is less than 2 % with an illumination area of more than 400 cm2. It is shown that the tested measuring complex allows for automated research of solar cells in irradiation regimes corresponding to both terrestrial irradiation conditions and extraatmospheric solar radiation conditions. The possibility of individual adjustment of each of the 36 channels of the emitting element in the range from 400 to 1100 nm has been tested, which adds flexibility in the use of the Sunbrick sun simulator during the study of both solar cells as a whole and the properties of functional semiconductor materials by irradiation with monochromatic or mixed illumination. It is shown that due to the rapidity of conducting research and the ability to immediately visualize the measured current-voltage characteristic on the computer screen, it is possible to significantly speed up the process of researching solar cells. Thus, it is possible to immediately divide the investigated solar cells into groups in relation to their efficiency and determine the presence of possible defects or damage in their structure.

The main goal is to create a basic solution for a pliable, thin-film PVC that utilizes the $\mathrm{CdS} / \mathrm{CdTe}$ heterosystem modified to suit specific needs for mounting a solar panel from some photovoltaic converter directly to the heat collector plate as part of A self-sufficient integrated photovoltaic system designed for both military and civilian purposes, utilizing conventional solar thermal collectors, forms basis of such type systems. The central element of this setup is a photo generating unit, consisting of a typical solar water heating collector on frontal panel of which the flexible solar battery from $\mathrm{CdS} / \mathrm{CdTe}$ photovoltaic converters is installed. Research findings indicate that a flexible photovoltaic converter employing cadmium telluride exhibits a excellent absorption of sunlight within the $400-800 \mathrm{~nm}$, ranging from $94 \%$ to $96 \%$. Moreover, the reflectance of long wave part of sunlight remains below $8 \%$, leads to simplify system constructive, because film photoelectric converter work as absorber with selective coating. The calculation of the thermal conductivity of flexible photovoltaic converters based on cadmium telluride, experiments conducted on a $7 \mu \mathrm{m}$ thick polyimide film demonstrated that considering the thermal conductivity coefficient of polyimide, ranging from 0.14 to $0.20 \mathrm{~W} /(\mathrm{m} \cdot \mathrm{K})$, it is feasible to achieve a heat gradient in a such photovoltaic converter in the range of $0.6-0.9^{\circ} \mathrm{C}$.

With the use of modernized industrial vacuum installations, a series of test samples of cadmium telluride films was produced by the method of thermal vacuum evaporation on glass substrates without a sublayer of transparent conductive oxide, with a sublayer of conductive oxide, and on molybdenum foil substrates to study the influence of the substrate material on the structural parameters of the test samples. The study of the structure was carried out by the method of X-ray diffractometric analysis, the parameters of the lattice, the sizes of the regions of coherent scattering and the texture coefficient of the film were calculated. Based on the results of research into the structural parameters of samples made on a glass substrate, the presence of a cubic phase of cadmium telluride was established. It is shown that when the temperature of the substrate increases, the texture of the samples increases and the presence of tensile stresses is observed, since the lattice period of the cubic phase is significantly higher than that of the tabular phase. For a sample obtained on a glass substrate with a layer of transparent conductive ITO oxide at a substrate temperature of 200 ОC, the presence of two hexagonal phases H1 and H2 and a cubic phase C was established. The samples obtained on a molybdenum foil substrate contain almost entirely the cubic CdTe phase only in very thin sample no. 1 traces of the hexagonal phase are present. For the first thinnest sample, only one main diffraction peak of the cubic phase is observed, which can be explained by the fact that in the initial stages of the film growth, it grows as a highly textured cubic phase with the possible presence of some hexagonal phase. From the analysis of the obtained results, it can be noted that the samples obtained on the molybdenum substrate have a lattice parameter closest to the table data - 6.482–6.483 Å. The structural differences observed between the studied samples are due to the fact that they have a different preferred orientation, which is most likely due to a change in the sputtering speed

The article presents the design conception of a high mobility energy generation and storage system with intelligent energy conversion and storage systems for use in military and civilian purposes in regions with damaged infrastructure, where access to electricity and hot water is limited or threatened due to man-made actions or natural damage.The proposed system main feature is modular design which combines a heat collector, electrical energy converter, and related energy storage systems.The modular, reliable design and ease of deployment of the proposed system, the size of which allows to carry out in standard shipping containers, enables rapid and flexible scaling of a deployed solar power plant, production and storage of electricity and hot water.The design of the module of the proposed system is based on the use of highly efficient multi-junction III-V solar cells in combination with economically and reliable plastic made system for concentrating solar radiation.At the same time, the cooling of solar cells to maintain their operating temperature provides heating of water to the minimum values required in domestic conditions.Also, the modular principle is the basis of the system for storing and distributing electrical energy, which is supposed to be made of highly efficient Li-Fe based rechargeable batteries, which today have one of the best indicators in terms of the ratio of volume and accumulated energy.An intelligent control system based on microcontrollers provides accurate positioning of solar cells, the implementation of the MPPT algorithm to maximize power generation and maintain a balance between supplying consumers and charging batteries.Modularity makes it possible to form emergency power supply complexes of different power (45 W of electric power and 50 W of thermal energy per one module) for provide emergency and permanent power supply of most electronic devices according to the standard protocols PD 3.0, QC 3.0, 12 V, 220 V as well as supply consumers with warm water for basic needs.

Purpose. The introduction of electronic load for testing high-precision low-voltage sources (solar panels) requires careful review not only of the circuit design, but also thermal and mechanical design. The article considers the principle of creating and calculating the optimal solution for the implementation of electronic load. Methodology. To achieve this goal, methods of analysis of modern electronic database, calculations of basic physical and electrical parameters and their modeling are used. Findings. Based on the considered physical and circuit solutions for the implementation of the electronic load unit, a corresponding electrical circuit was developed. The transistors are controlled by four unipolar operational amplifiers integrated into the LM324 chip. Control of the electronic load unit is implemented by controlling the voltage at the positive feedback terminals, which is further stabilized by the TL431 chip. The device is powered by a source of DC stabilized current of 12 V (provides additional filtering from voltage fluctuations). Originality. Modern advances in the development of solar cells and other low-voltage energy sources have led to the need to create compact and express systems for testing them, which cannot be implemented on existing solutions. Practical value. Adherence to the indications and principles set out in this article will provide the load with the ability to work at high power, while maintaining good performance and reliability. The developed scheme allows to create a compass device for express testing of solar panels.

Solar collectors and thermophotoelectric systems (PV/T) are considered, which are one of the most promising systems for instilling energy. Electricity, which is vibrated by photovoltaic panels, has a great potential, but there may be technological shortcomings, which do not give maximum efficiency. Development of a general model of heat exchange processes for optimizing the design features of PV/T systems at the stages of design and variability allows us to increase the term of service of such systems and increase their efficiency. The expanded model allows you to change more practical parameters for two coordinates of a flat collector, such as to change the consumption of thermal energy, thermal support of the absorber plate, heat exchange, operating temperature, etc. The results of the model investigations correlate with the experimental data. On the basis of the proposed model, a software product for the model-bath of PV/T systems was developed and tested on the experimental results of those ready-to-wear PV/T systems. In the course of carrying out the expansions, depending on the basic parameters, the heating of heat was removed when one segment of the collector was passed by approximately 1.5 °C. The designated increase in temperature is reached at a heat transfer rate of 0.6 m/s, which is to achieve a great rate. The most optimal will be the heating of heat when passing through the collector by 5 °C, which will allow to reduce the speed of heat transfer to 0.2 m/s and significantly reduce the amount of electricity consumed by the pump. The variation of the expanded model allows to implement a wide range of optimization tasks at the stages of designing and optimizing solar collectors and PV/T systems, to take the optimal design parameters to achieve the greatest efficiency and minimum occupancy.