The aim of the presented work, which was presented at the conference [1], is to review modern agrivoltaic systems, technologies for producing green hydrogen using solar energy and the possibilities of joint application of these systems.

To improve the reliability of power supply in autonomous energy systems, it is necessary to expand the time range for regulation. This is required to create an adequate reserve of resources capable of compensating for peak loads and effectively managing backup capacity. Currently, there are two key methods for solving this problem. The first method is based on mathematical modeling of the expected level of solar insolation by analyzing historical data on actual levels of insolation in the past. The second method uses current insolation forecasts developed based on global and regional climate research and forecasts. In addition, improving climate information collection systems using ground-based and space observation tools increases the accuracy of weather forecasts, making them applicable to practical tasks in the energy sector.

This work is devoted to studying ways to improve the accuracy of medium-term forecasting of energy production by solar power plants using meteorological data and cluster analysis of meteorological conditions. The main goal of the study is to test the effectiveness of the indirect forecasting method, which is based on open meteorological data such as solar insolation and cloud cover.

The article discusses the use of global climate models to predict energy output from solar power plants. A methodology for calculating incoming solar radiation onto a surface inclined at an angle to the horizon is presented.

The results of experiments conducted at the FSNEI-65 solar power plant located on the south facade of the educational building of Ural Federal University in Yekaterinburg are presented. During the experiment, predicted values of solar insolation and cloudiness obtained using the Integrated Forecast System (IFS) climate model were compared with the actual electricity generation by the solar power plant over an average period of time. Graphs of the dependence between real and predicted power were constructed, and forecast deviations were calculated.

The results show high accuracy of climate models in medium-term forecasting and their potential for reducing costs associated with compensating for underproduction of energy by solar power plants.

This paper presents the results of an experimental study of a solar station connected to the grid, installed on the facade of the Ural Power Engineering Institute (Russia, Yekaterinburg). For 3 months of operation in the autumn­winter period, the solar power plant produced over 20000 kWh of electricity, providing lighting for 3500 square meters of corridors of the educational building (without natural light); made it possible to verify the developed models for assessing energy production according to meteorological forecasts; Reduce carbon dioxide emissions by more than 8 tonnes. 

The article presents the results of studies of the nature of changes in the graph of the wall temperature dependence on the heat flux density, which established that regardless of the position of the pipe and the direction of fluid flow at supercritical pressures and tc ~ tm, a mode with improved heat transfer occurs. The onset of improved heat exchange when the temperature of the inner wall surface reaches the pseudocritical temperature of the studied liquid (n-heptane) undoubtedly indicates the influence of changes in thermophysical parameters on the heat transfer process. Under these conditions, all thermophysical properties, changing sharply, obtain their extreme values. Moreover, with distance from the critical pressure, as shown by the results of studies of thermophysical properties, and in the pseudocritical tempera­ture region, the rate of change of physical parameters noticeably weakens, which should have a certain effect on heat transfer.

This article presents the results of studies of the physical properties of hydrogenated amorphous thin films of a-Si_1-xG_ex:H and a-Si_1-xC_x:H alloys obtained by plasma chemical deposition. The optical constants (n, n, a, R, d) and the band gap of the films under study (E₀ = 1,05-3,00 eV) were determined. Based on a study of the optical properties of various deposition modes (T_pod, d, H₂), the substrate temperature, film thickness and the level of hydrogenation of the alloys are characterized by different structural phases. With a change in technological parameters, various structural and polymer phases of crystallites are also obtained: nanotubes, nanowires, nanoparticles, quantum wells, quantum dots, graphenes, graphites, decanters, fullerenes, diamond particles, clusters, etc.

The structure of the deposited nc-Si:H films is mixed-two-phase and consists of nc-Si:H nanocrystallites «distributed» in an amorphous network. Annealing of crystalline films at a temperature of 700 ⁰C increases the crystal­lite size to 50-100 A⁰ in diameter, and the conductivity changes slightly. Also, when hydrogen is introduced into an amorphous silicon film at low temperatures (T_s < 100 °C) with a higher hydrogen content (~ 30 atm.% or more), the material contains an excess of the SiH₃ group, as well as slightly more hydrogen in the polymer form (SiH₂)_n. The con­centration of carbon and hydrogen in a-Si_1-xC_x:H films depends on the deposition conditions and the initial gas mixture of SiH₄, CH₄, H₂. Depending on the choice of modes, with increasing concentrations of hydrogen H₂ and CH₄, films are deposited in polymer form.

Possibilities of plasma chemical deposition of a-Si1_-xGex:H (x= 0-1) films undoped and doped with PH3 or B2H6 have been analyzed from the viewpoint of their application in p-i-n structures of solar cell. The optical properties are considered, and the amount of hydrogen contained in those films is determined. The film properties are found to strongly depend on the film composition and the hydrogenation level. The number of hydrogen atoms in the films is varied by changing the gas mixture composition, and IR absorption in a-Si:H and a-Ge:H films is measured. The a-Si:H and a-Si Ge:H films were used to fabricate three-layer solar with an element area of 1,3 sm² and an efficiency (£) of 9,5%.

Obtaining energy carriers convenient for storage, transportation and use for direct use in energy and transport is one of the urgent tasks. In this work, the energy efficiency of the batch technology for obtaining ethanol from sugar3? containing raw materials at the stages of fermentation and rectification is evaluated by experimental and theoretical methods.

In this work, an industrial thermoelectric installation was experimentally studied after a long time of operation at a real facility. A conclusion is made on the reasons for the mismatch and degradation of semiconductor structures. Methods for optimizing the design of these installations by creating a passive thermoregulation system are proposed.

In the course of the work, 3 experimental stands were assembled to conduct experiments and identify reproducibility.
The effect of ultrasonic vibrations on the electrolysis process was also studied. To achieve the result, the following tasks were solved:
1. A literature review of domestic and foreign patents on devices for the electrolytic decomposition of water under the influence of ultrasound was performed.
2. An experimental setup for the separate production of hydrogen and oxygen was developed.
3. Methods for measuring the volume and pressure of gases released during electrolysis were developed.
4. An assessment of the errors in the measured values was performed. The error in measuring the pressure of Brown’s gas is ± 0,3%; the volume of released hydrogen is ± 3,32 cm³;
5. Experimental studies were carried out on installations at currents from 3 to 8 A when applying ultrasound of a fixed frequency of the low-frequency ultrasonic range.
6. The use of hydrogen and Brown’s gas is possible in chemical energy storage systems for subsequent conversion into electrical energy or in internal combustion engines on hydrated fuel. 

In order to utilize food waste, the amount of which increases every year, an experimental setup for dark fermentation of organic waste was developed within the framework of the RSF project No. 22-49-02002 (https://rscf. ru/project/22-49-02002/). This study is aimed at assessing the effect of the feed rate of the substrate pre-treated in the ABC on the efficiency of biohydrogen production during dark fermentation. According to the data obtained, the feed rate of the substrate pre-treated in the ABC to the dark fermentation reactor has a significant effect on the dynamics of biohydrogen formation from organic matter: a decrease in the feed rate led to a decrease in the amplitude with an increase in the average value of the volumetric yield of biohydrogen (by 18% to 0,62 l / (l h) with a decrease in the feed rate by 3 times). Thus, an increase in the substrate feed frequency makes it possible to reduce daily fluctuations in the biohydrogen yield while simultaneously intensifying the dark fermentation process.

The accumulation of organic waste, including by-products of animal husbandry and food waste, is a serious environmental problem, and at the same time, organic waste is a major source of renewable energy. For the disposal of organic waste, an experimental setup for two-stage anaerobic bioconversion of organic waste was developed within the framework of the RSF project No. 22-49-02002 (https://rscf.ru/project/22-49-02002/) to produce biohydrogen at the stage of dark fermentation and biomethane at the stage of methanogenesis. This study is aimed at assessing the effect of using a microbial electrolysis cell on the intensity of biomethane production from the effluent of a dark fermentation reactor during two-stage anaerobic digestion of a food waste model pretreated in an ABC. According to the obtained data, the use of a microbial electrolysis cell in a two-stage anaerobic digestion system of a food waste model pretreated in an ABC allows to increase the yield of gaseous hydrogen carriers in the form of biomethane by 57% with a potential difference on the MEY electrodes of 1,2 V. The energy contribution of dark fermentation to the total volumetric energy yield was 58.8-66.2%. Thus, the use of a microbial electrolysis cell with a potential difference of 1,2 V allows to increase the energy yield of the two-stage anaerobic digestion system of a food waste model pretreated in an ABC by 33%.

At present, when considering the problem of the impact of energy on climate change, the international community considers the main factor determining the greenhouse effect and, as a result, the increase in the temperature of the planet’s geosphere a man-made increase in the content of carbon dioxide in the atmosphere. At the same time, it is well known that the main greenhouse gas that ensures the temperature stability of the planet is the water vapor present in the atmosphere.

This work, an attempt is made to take into account the additional enhancement of the greenhouse effect, taking into account water vapor entering the atmosphere as a result of energy production at power plants of different types using different types of fuel (gas, coal, fuel oil, uranium).

Purpose of the work is to expand the consideration of all the main sources of gas products accompanying energy production, in order to select promising technological solutions that prevent further strengthening of the greenhouse effect and climate change.

In the art investigation materials of charged particles and electromagnetic waves interactions in plasma setup Magnetic V dipole developing by authors are presented. It was experimentally distinguished that current increasing in specially formed electromagnetic resulting field arises as result of parametric resonance and phase transformations electric energy, kinetic energy of charged particles and magnetic energy. Current loop is formed, where start bifilar current of heteropolar charged particles. It leads also to current increasing with each plasmoid rotation cycle around system center of mass. Process is stabled in phase of electromagnetic energy irradiation. The energy can be used on load like electricity. In experimental setup launches was obtained power increase on 42% from power supply by non-resonant mode and on 142% by resonance mode.

Method and the setup were successfully applied for destruction of crystal lattice of minerals, industrial wastes with separation of useful components and metal extraction. Method of plasma resonant electrolysis was developed, and experiments for sedimentation of gold containing pulp carried out. Possibility of gaseous hydrogen producing with application of high frequency plasma resonant electrolysis was experimentally indicated. The process can be built in the MVD setup.

In the course of the work for experiments and efficiency studies, the previously developed unit was modified and experimental studies were carried out in the flow range from 0,4 to 1,15 l/s for heating and heated media for the design boiling point of the intermediate coolant in closed two-phase evacuated water-filled thermosiphons equal to 60 °C. It has . been established that the use of a thermal siphon in an inclined position is more effective for heat transfer. It is shown that the effect of inclination on the power of a thermosiphon heat exchanger depends on the boiling mode of the working £ fluid, maximum when operating in bubble boiling and minimum when operating in projectile and hypershell modes                                                                                                                                                                                                                  

Thermal energy accumulation will allow consumers to keep heat in rooms several times longer than electric heating, which will reduce fuel consumption at thermal power plants and level the schedule of daily electricity consumption of the power system.

The use of electricity for heating makes it possible to solve the problem of accumulation and subsequent use of «night» electricity during the hours of failures in the load schedule of the power system using the two-tariff pricing principle. Calculations using the non-stationary heat balance of an apartment building in Yekaterinburg with electric h       heating showed a possible reduction in financial costs for heating by 3,86-5,18 rubles / m2 with overheating of the              building structures by 2-3 °C compared to electric heating without overheating at night. The efficiency of the electric heating system increases significantly with a slight overheating of the building at night by 1-4 °C, which practically does ' not affect the comfort of the living regime.