Potential induced degradation (PID) can reduce photovoltaic (PV) plant output by up to 30 % within a single year, primarily due to voltage driven ion migration and leakage currents. This study proposes a cost effective mitigation strategy that couples deep, vertical composite electrodes with a hydrogel-graphite backfill (GGG mix) [2]. The backfill reduces soil resistivity, stabilizes seasonal fluctuations, and limits the module-ground potential difference. The experimental photovoltaic station with a capacity of 30 kW (located on the territory of the Namangan State Technical University of the Republic of Uzbekistan, which is dry and has a soil consisting of a mixture of sand, stone and soil, the characteristics are the same as in the semi-desert) was equipped with three grounding configurations. Over 52 weeks, the GGG mix system lowered ground resistance by 45 % and cut the annual PID power loss index from 6.5 % to 1.8 %. Modelling confirmed an equivalent electrode diameter almost eighty times larger than a conventional 12 mm rod. Economic analysis indicated a 20 % reduction in installation cost relative to pre drilled electrodes. The proposed method therefore offers a practical pathway to PID resilient PV deployment in high resistivity soils.

A method for reducing the resistance of the ground loop for high-resistance soils by using mixtures based on hydrogel is considered as backfill materials. Based on the results of the research, an analysis was made of the effect of mixtures on soil resistivity, the seasonality factor and the resistance of the ground loop at various temperatures and humidity.

This paper discusses a method for using mixtures to optimize the electrical parameters of grounding devices during the installation of vertical composite ground electrodes. The authors propose a design for the coupling and tip for vertical composite ground electrodes. Various techniques for artificially reducing the resistance of the grounding circuit are examined. Results from vertical electrode soundings of the soil at grounding locations are presented. The proposed method allows for the introduction of a mixture simultaneously with the vertical composite grounding electrode, including designs for the coupling, tip, and auxiliary device. Experimental studies of the proposed design have been conducted, and results measuring the resistance to current spread of such grounding devices are presented for both standard and proposed couplings.

Traditional analytical methods for calculating and designing of grounding devices (GDs) in heterogeneous soils can lead to results that do not correspond to those obtained in practice. The empirical coefficients used in calculations of grounding systems given in various literature sources do not always give an explicable and significant discrepancy with the same initial data. In this paper, some well-known methods for calculating the spreading resistance of GDs are considered and the obtained results are compared with experimental data. It is shown that the recommendations and algorithms for calculating the resistance of GDs, presented in the well-known reference literature and regulatory documentation, do not give full and correct description for grounding devices installed in heterogeneous soil. In particular, it is shown that such a factor as the proportional ratio of soils with different resistivity practically does not affect the final result. This fact may mislead specialists, since the results obtained may differ significantly from what is observed in practice after the installation of GDs. The study proposes a calculation method and shows a fairly good convergence of the results with experimental data, and defines a further direction in optimizing calculation methods GDs.

The article considers the method of using mixtures to optimize the electrophysical parameters of grounding devices in conjunction with vertical composite grounding conductors. It has been found that fluctuations in soil resistivity caused by changes in weather and climatic conditions can lead to instability of the ground loop resistance. The study shown that without appropriate measures, the resistance of the loop as a result of seasonal changes in soil properties may exceed acceptable values. This is fraught with deviations in the resistance to current spreading of grounding devices beyond the limits of acceptable parameters. To compensate for these fluctuations, a method is proposed to reduce the seasonality factor. Reducing seasonality plays an important role in ensuring the safety of service personnel and farm animals by maintaining the resistance of the grounding device within the limits of regulatory values. The authors discuss methods for artificially reducing the resistance of the ground loop, including increasing its size and using deep ground electrodes. The results of vertical electrode probing of the soil at the sites of grounding conductors are presented, the effect of humidity on the resistivity of the soil is shown, the influence of soil layering and the presence of moisture-saturated soil layers is considered. A method is proposed that allows the mixture to be introduced together with a vertical composite grounding device, the design of the coupling, tip and auxiliary device, experimental studies of the proposed designs are carried out and the results of measuring the current spreading resistance of such a grounding device with both standard and proposed couplings are presented. A comparison was made with a grounding device without the use of mixtures. The measurement results demonstrate that with an increase in the length of the grounding device, its diameter and the volume of the injected mixture, the resistance decreases. It is shown that the proposed solution makes it possible to reduce seasonality by 1.64–2.1 times, depending on the couplings used, and to obtain a grounding conductor with an equivalent diameter dozens of times larger than the diameter of a composite grounding conductor. The authors propose the use of soil-replacing mixtures to reduce soil resistivity and ensure the stability of the grounding loop throughout the entire service life. The proposed method of applying mixtures without pre-drilling makes it possible to reduce the cost of constructing grounding devices.

The possibility of improving the reliability of the grounding system is shown. The analysis of dependence of soil resistivity on humidity was carried out, on the basis of which a composition for normalization (reduction of seasonality) of soil electrical resistivity was proposed. A number of full-scale experiments were carried out to measure the resistance values of the grounding devices of experimental circuits, after backfilling the places of laying the contour elements with various compositions and introducing other types of soils and minerals.

This article discusses the factors that affect the electrical resistance of the current spreading of the grounding device. The issue of the electrophysical parameters of the soil that affect its resistivity and the consideration of such parameters in the design of grounding devices is considered. It is shown that keeping moisture in the near-electrode space of the grounding electrode, as well as maintaining it at a certain level, facilitates improving the quality and reliability of the grounding. A relationship has been established between the ability to retain moisture and the magnitude of seasonal fluctuations in the electrical resistance of the soixl, and also the season factor, which takes into account changes under different climatic environmental conditions. The issues of application of various methods of reducing the resistivity of the soil during mounting of grounding devices are considered. One of the main ways to reduce ground resistance is the use of solutions of various mineral salts. This method is not optimal, as it accelerates the corrosion processes in the materials of the ground electrodes. Therefore, the paper also considers other ways to reduce the resistance of the ground loop; in particular, the authors propose a method for reducing the resistance of a grounding device based on the method of partial replacing the soil in the near-electrode region with a mixture with a lower resistivity capable of collecting moisture based on graphite and hydrogel. This type of mixture is environmentally friendly when used, as well as it is non-aggressive to the material of the ground loop. The principle of operation of this mixture is based on the fact that the hydrogel makes it possible to stabilize the moisture at the site of laying the circuit, while graphite increases the overall conductivity of the mixture. The paper presents the results of laboratory studies, which have been carried out in accordance with GOST 9.602–2016. For this purpose, control samples were placed in containers made of a non-conductive material (plexiglas) and dependence of resistivity on moisture, temperature, specific content of graphite and hydrogel was measured. The article presents graphs of the dependences of the mixture specific resistance on moisture, temperature, and the quantitative content of the hydrogel. From the results obtained, it can be concluded that the mixture in can be used in the energy sector to improve the reliability of electrical installations and ensure electrical safety.

THE PURPOSE. The purpose of the article is to define the reasons to improve the system of grounding devices design. Author studies technical decisions that reduce grounding resistance values. Results are given researches how a mineral conductive mixture, that normalizes grounding, influences a seasonal coefficient. Analysed the results of the experimental surveys. Аlso evaluates a test grounding devise’s resistance decrease compared to the resistance decrease of a control grounding device. METHODS. While solving the above problem, a number of field experiments were carried out to measure the resistance values of experimental circuit grounding devices after their near-electrode soil space had been treated with the mixture that improves the resistance of a grounding wire. RESULTS. The composition of the mixture that normalizes (reduces) soil electrical resistivity has been developed, it has contained hydro-stabilizing and lowdispersed conducting additives. There has been proposed the analytical expressions to evaluate equivalent soil electrical resistivity values after aporton of soil had been submitted by the mineral conducting mixture. CONCLUSION. The use of the mixtures based on hydrolyzed polyacrylonitrile is most effective together with the grounding wires buried in soil no deeper than the soil freezing depth that is located in the soil layers with maximum seasonal fluctuations, and will increase with the increase of the contact area of such grounding wires with the soil treated with hydrolyzed polyacrylonitrile. Additional decrease of a seasonal coefficient for the vertical compound grounding wires apparently is due to the mixture influencing their parts mounded near the ground surface. The use of complex mixtures containing both hydro-stabilizing additives and low-dispersed conducting substances allows up to three times decrease of the resistance values of a grounding device compared to a control grounding device, it allows to even seasonal fluctuation of resistance of a grounding device, and to decrease mounting capital investment for a grounding device by means of the decrease of the number of the electrodes and the territory on which they are located.

Low-temperature XRD measurements were performed to confirm the phase composition and structural parameters of the electrochemically deposited Cu2ZnSnSe4 thin films on flexible metal substrates.

The paper considers the reasons to improve the design system for the grounding devices. It proposes a special-purpose composite mixture to reduce the soil electrical resistivity values. A number of field experiments were carried out to measure the resistance values of the grounding devices of the experimental circuits, after their near-electrode soil space had been treated with a special mixture to optimize the electrical resistivity of the grounding connection.

Investigations into the influence of the substrate type (a glass substrate with a molybdenum sublayer, tantalum and molybdenum foils) on the surface morphology of Cu2ZnSnSe4 thin films obtained by selenization of electrochemically deposited and preliminary annealed metallic precursors are presented. Metal foils are attractive for use as substrates of solar cells in both ground and space objects due to their light weight, flexibility, and the possibility of using the commercial roll-to-roll technology of film fabrication, leading to a reduction in the cost. At different stages of Cu2ZnSnSe4 film preparation, their surface morphology is studied by atomic-force microscopy and scanning electron microscopy in combination with energy-dispersive spectrometry. The metal substrate morphology is demonstrated to have an insignificant effect on the surface morphology of Cu2ZnSnSe4 films, indicating that flexible-foil substrates are promising for the production of thin-film solar cells.

In this paper a composite structure, topography, wettability and nanohardness of a (100) Si surface modified by means of ion-assisted deposition of metal (Me) coatings in conditions of a self-irradiation are discussed.

Elemental composition, roughness, and wettability of a graphite surface modified by ion-assisted deposition of a Cr coating ∼300–1000 nm thick are investigated using the methods of Rutherford backscattering, atomic force microscopy, and contact angle measurements. It is established that, in addition to chromium, coatings involve hydrogen, carbon, and oxygen from residual gases of a vacuum chamber because of their incomplete pumping by vacuum pumps and 1–2 at % silicon diffusing from the graphite. It is determined that, as the coating thickness increases, the surface roughness of the modified graphite increases and becomes the predominant factor in increasing its hydrophobicity.

The structure and phase composition of lightly-doped Al-Fe alloys obtained by ultrarapid quenching from the melt are investigated. The surface of foils was studied using scanning electron microscopy, atomic-force microscopy, and Rutherford backscattering technique. The variation in the phase composition of alloys during annealing was studied by x-ray diffraction technique and by resistivity and microhardness measurements. The Al-Fe alloys have microcrystalline structure with a nonuniform iron content in the near-surface region of the samples. A correlation of depth profiles of iron and phase composition of the foils is observed. It is found that decomposition of the supersaturated α solid solution proceeds in the temperature range 250–350°C. As the annealing temperature increases, a metastable Al6Fe phase is precipitated. In the range 300–500°C, the metastable Al6Fe phase decomposes, and a stable Al3Fe phase is precipitated.

The composition of Ti- based thin films deposited on silicon using a self- ion assisted deposition ( SIAD) methodwas investigated by utilising the Rutherford backscattering spectrometry technique and RUMP simulation code. The hydrogen affinity of the coatings produced by means of SIAD was investigated using the H-1(N-15, alpha gamma) C-12 nuclear resonance reaction. The titanium - based films on silicon were found to have a high content of oxygen, carbon, hydrogen and substantial concentration of the substrate. Near 10% H content enrichment was found at the surface of coatings but no hydrogen enrichment at the coating - substrate interfaces was observed.

The composition and structure of Ti, Zr, Mo - based thin films formed on silicon and rubber by ion-beam-assisted deposition were investigated by utilizing the AFM and RBS technique. It was found that the films included not only metal atoms but also C, O, H, Si (from Si substrate), S, Ca and Zn (from the rubber). The coatings on the rubber have quasi-periodical topography which may be due to build in stress. The coatings on silicon are uniform with a smooth surface.