Vol 55, No 3 (2019)

Power supply to consumers, especially in remote areas, is often subject to emergency power outages. This leads to numerous problems such as the breakdown of household appliances and electronics, the inability to provide vital functions in homes and special institutions, and production failure. Also, grid companies sometimes cannot efficiently provide energy to private consumers due to insufficient capacity of the power grid. This journal discusses the use of power plants on alternative energy sources and systems of accumulation of electric energy connected to renewable energy sources. Such systems can be used in parallel with the existing electric power grid, as well as directly by autonomous consumers. This journal also describes the possibility of providing electric power to individual consumers using solar panels in combination with a system of accumulator batteries. The process of charge–discharge of capacitive batteries in the photovoltaic module–battery system is studied in order to increase the efficiency of low-power autonomous power plants. Studies show an increase in the efficiency of the system designed for the individual consumer by 30%, as well as the possibility of uninterrupted operation. The proposed model of the combined photovoltaic and storage system avoids the problems associated with emergency power outages. More importantly, for various Russian Federation regions that are neither close to the generating facilities nor have reliable uninterrupted electricity supply, the presented system can significantly extend both the time of efficient use of energy resources and the service life of the equipment.

The light load current-voltage characteristics of a solar photovoltaic module based on amorphous hydrogenated silicon have been studied at different temperatures under conditions of natural solar illumination (Р_rad = 870 ± 10 W/m²). It has been found that the temperature dependence of the photocurrent has two slopes due to a change in the generation–recombination mechanism. The increase in the value of the short-circuit current with increasing temperature of the photovoltaic module is explained by a rise in the drift lengths of minority charge carriers due to an increase in the lifetime of minority carriers. In this case, the quasi Fermi level shifts to the conduction band, and the concentration of recombination centers decreases due to recharging of defective levels (D⁰ → D^–). The decrease in the value of the open-circuit voltage with increasing temperature is explained by the exponential increase in the reverse saturation current and decrease in the band gap of the semiconductor. It has been found that the fill factor (FF) of the current–voltage characteristics decreases with increasing temperature, most likely due to a decrease in the shunt resistance (R_sh), which connects parallel to the p–n junction, consists of parasitic resistances, and leads to an increase in leakage currents. The temperature coefficient of the maximum output power has a positive value in the range of 320–332 K, i.e., increases with temperature. It has been revealed that the values of shunt and series resistance decrease with increasing temperature. A large loss of power output (up to 19%) has been observed on the series resistance of the solar photovoltaic module in the temperature range of 320–332 K. With increasing temperature, the loss of generated power on the shunt resistance grows sublinearly. The efficiency of the solar photovoltaic module decreases from 7.95 to 7.65% and has a coefficient of temperature dependence of efficiency, which decreases from \({{K}_{{{\text{Ef}}{{{\text{f}}}_{1}}}}}\) ≈ –0.046 to \({{K}_{{{\text{Ef}}{{{\text{f}}}_{2}}}}}\) ≈ –0.029%/K.

Automated Sun-tracking systems are important elements of solar power devices, which make it possible to increase the amount of solar energy converted to consumer formats during the daylight period, especially true for devices with solar energy concentration. In this study, we investigated the parameters of functioning of the Sun-tracking system built into the photovoltaic thermal installation with parabolic cylindrical concentrators of solar radiation, as well as the main characteristics of the complex as a whole. With attention to the installation structure and tracking system schematics, the studies were carried out on natural solar radiation, with simultaneous measurement of the photovoltaic characteristics and the solar radiation flux density using a pyranometer. The installation parameters were estimated in relation to the angular motion of the Sun across the celestial hemisphere. Due to numerous heterogeneous factors affecting the result, the experimental data were largely statistical in nature. For this reason, the parameters were evaluated using methods of regression analysis. In a number of experimental dependences, the correlation coefficient of the short-circuit current and the solar radiation flux density reached 98%. The studies allowed us to estimate the accuracy of Sun tracking at 1.5–2 angular degrees. In this case, the short-circuit current in the photovoltaic part of the installation varied by ±4% within an hour. In the course of field studies, the fraction of scattered solar radiation was estimated at ~20% of the total intensity. The concentration coefficient of 5.0–5.1 times was calculated from the dependence of the short-circuit current on the solar radiation intensity.

The main objective of this paper is to analyze the techno-economic feasibility of installing a 300 kW grid-connected solar photovoltaic (PV) plant in Syria. Umm Al-Zaytun village in As-Suwayda province was chosen as a location of the plant, because it is characterized by the high annual solar irradiance on the horizontal surface of about 1900 kW h/m². Technical performance analysis, system configuration, detailed losses and energy yield simulation for a proposed PV plant were performed, using the PVsyst software. The simulation results show, that the annual optimal tilt angle of PV modules is 25°, energy production is 493 MWh/yr, the annual average performance ratio is 0.799 and the capacity factor is 18.7%. In addition, by considering, that the electric power consumption per capita in Syria is 2232 kW h/yr, so the proposed solar power plant with 493 MW h/yr can provide energy to 220 capita/yr and save about 42.4 tons of oil equivalent yearly with carbon emission reduction of about 320.45 tCO₂/yr. The economic evaluation of the proposed PV plant was carried out by Excel software with consideration, that the discount rate is 9%, the lifetime of the project is 25 years and the selling price of electricity to Syrian electricity distribution establishment is 0.119 $/kW h. The results of economic calculations show, that levelized cost of electricity is 0.094 $/kW h, the discounted payback period is about 11 years, the internal rate of return is 14%, profitability index is 1.46 and the net present value is 190587.3 $. As a result, the proposed grid-connected PV solar plant is considered economically, technically and environmentally feasible in Syria.

The factors influencing the energy system of the Republic of Crimea were studied. Analysis of generating capacity to ensure reliable power supply to consumers and sustainability of the power system in different periods of the year was carried out. Research of the renewable energy role in the power system management was conducted, including the improvement of methods of management and optimization of solar power plants capacity. A study of the data necessary to build an optimal model of power system management was performed. Power system efficiency increased in relation to the price of electricity for consumers. We proposed the development of methods to optimize the production of solar power plants, affecting the operation of the Republic of Crimea and the Middle East power systems. Studies have established the dependence of the power system on the changeable generation of renewable energy sources, thereby showing the impact of meteorological factors on the power system operating modes. One of the rational approaches is the use of genetic algorithms to solve the problems of structural-parametric optimization of energy systems modes. It will allow optimizing of the management of the Republic of Crimea power system, including the creation of opportunities for optimal loading of the network, taking into account various specified conditions. The work identified the potential of Iraq’s energy industry for renewable sources, where solar photovoltaic technologies are suitable for the production of electricity throughout Iraq, due to the uniform distribution of solar radiation throughout the country. The results of the work revealed that the result obtained is applicable not only to the power system of the Republic of Crimea, but also to other foreign power systems of the Middle East with a large number of renewable energy sources and the potential construction of new solar power plants, that can make it possible to optimize the power system management.

The article discusses the state and prospects for development of solar power plants with concentrators and their current-voltage characteristics, as well as the placement of solar modules in various positions; in addition, their technical and economic indicators are provided. The suggested project of a solar photovoltaic power plant in the Karakum Desert allows saving organic fuel and has the following performance features: the power is 1 GW, the annual electricity output is 1.3 to 1.7 billion kW h, and the power plant costs one billion Euros. This power plant is meant to supply electricity to consumption sites along HV DC power lines without using HV transducers and transformers at the transmitting substation to the neighbor states of Afghanistan, Pakistan, Iran, and Turkey.

The article provides information on the worldwide development of decentralized energy systems which are created on the basis of utilizing, distributing and storing renewable energy, using smart control systems, about energy storage in various energy storage systems, including pumped storage power plants considered one of the most efficient energy storage units. The map of a decentralized power system, based on a wind energy, a photovoltaic, and a pumped storage plant (PSP) is proposed; the methods of making estimates to determine its parameters are given. The article also provides the results of simplified estimates made to determine the main parameters of a 5 MW decentralized power system based on a wind power and a PSP, which prove the feasibility and efficiency of the proposed map.

The progress of work on the revising of building codes and regulations of the “Solar Hot Water Installations”, operating in the territory of the Republic of Uzbekistan is shown. The goal of the work is to create a modified republican regulatory document that meets modern requirements and provides an increase in the energy efficiency of designed solar hot water installations by 30%. The analysis was conducted with domestic and foreign experience in the design, and construction and operation of solar hot water installations for various purposes was studied and summarized. The selection of advanced technical achievements and scientific research of different countries in the field of energy saving and efficient use of solar energy has been carried out. In the process of revising the regulatory document, outdated regulations were excluded; new regulatory requirements were included, taking into account the current level of scientific and technological achievements, design and construction practices, and regional features of the Republic of Uzbekistan. The article introduces and substantiates main changes made to the previously existing building codes and rules, developed on the basis of the analysis of generally accepted results of completed research, development and experimental work, the study and synthesis of domestic and foreign experience in designing, building and operating solar hot water installations for various purposes.