Vol 54, No 5 (2018)

The objective of present study is to determine the energy and exergy performance of 50 W solar panel. Experimental study was conducted in the month of April and May (2016) under Udaipur climatic conditions (24°35′7″ N; 73°42′45″ E). Energy input, exergy input, exergy output, and exergy losses were estimated. Module temperature affects the performance of solar PV system. Owing such an issue both energy and exergy were found always higher in the morning hours as compared to noon time. Energy efficiency was found always higher than that of exergy efficiency.

Features of the appearance of photoconductivity in structures with nanoinclusions having a band gap width greater than that of the base material are investigated. The samples were structures with nanoinclusions located periodically and at equal nanodistances from each other. It is shown that the intervals between nanoinclusions can form quantum wells. Analytical expressions are derived to calculate the photocurrent and photoconductivity in such structures.

The Ising model of segregation of halide ions in hybrid perovskites upon illumination allows obtaining the relationship between the long-range order parameter of segregation and temperature taking into account the interaction of iodide ions fluctuations with an electron-hole pair generated by light.

The basic parameters of silicon carbide heaters and the reasons and criteria for their insufficiency for further use are considered. The article discusses methods to restore the operating parameters and the possible use of silicon solar cells for the express determination of the heat transfer of the restored silicon carbide heater.

The solubilities of sulfur are determined by neutron activation analysis and silicon compensation by sulfur with different concentrations of the initial boron. It is shown that the sulfur solubility at a silicon doping temperature of 1250°C is ~1.8 × 10¹⁶ cm^–3. Joint analysis of the results of studies of photoconductivity (PC) spectra, both in combined illumination with integral and infrared (IR) light and after the integral light is switched off, and the results of a study of the isothermal relaxation spectra of the capacity (DLTS) of Si❬S❭ crystals manufactured at different pressures of the diffusant vapor been established that single sulfur centers in silicon create two deep levels of E_S – 0.12 and E_S – 0.18 eV. All of the remaining energy levels of E_S – 0.27 and E_S – 0.53 eV are related to the quasi-molecules S₂ and S₄, respectively.

The epitaxial layers of the solid substitutional solution (ZnSe)_{1 – x –  y}(Si₂)_x(GaP)_y (0 ≤ х ≤ 0.01, 0 ≤ у ≤ 0.09) have been grown on pSi substrates via liquid-phase epitaxy of a limited volume of stannic solution melt. The spectral dependence of the photosensitivity of pSi–n(ZnSe)_{1 – x –  y}(Si₂)_x(GaP)_y structures is studied, and peaks of photoresponses are detected with photon energies of 1.6, 1.66, and 1.92 eV at ambient temperature. It is shown that the direct branch of volt–ampere characteristic stably retains its parameters within the temperature range 20–120°C. The values of the “characteristic” energy, as determined from the temperature-independent, volt–ampere characteristic, are 0.33 eV.

This article describes the main photovoltaic plants in deep-water lift systems of the remote and dry districts. The developed innovation circuit, which uses a special, multipurpose controller, is more flexible and energy efficient; it combines the principal advantages of common circuits. Data on the use of such solar photovoltaic plants in Uzbekistan, the number of which at present is more than 50, is presented.

The structure of a flat-plate photovoltaic-thermal system and its thermal circuit are considered. A method is proposed for the determination of heat losses and the temperatures of the front layers of a photovoltaic-thermal system with the specified operation conditions and a known temperature of the absorbing surface.

The advantages of the melt technique for the synthesis of superconducting materials are shown in comparison with the solid phase technique. Glass crystal precursors of the Bi_1.7Pb_0.3Sr₂Ca_(n – 1)Cu_nO_y series (n = 2–20) synthesized with SFAQ-T (Super Fast Alloys Quenching) technology under the influence of concentrated solar energy are used to produce superconducting Bi/Pb phases with increased superconducting transition temperatures.

This paper presents the thermal performance of a single stage solar adsorption system. The study includes a thermal performance comparison between two different locations in North Africa (Cairo and Casablanca) under different climate conditions. It was found that the solar fraction of the adsorption system is better under Cairo climate due to the relatively low daily solar radiation of Casablanca compared to Cairo. The solar fraction of the cooling plant was investigated theoretically for six months. The effect of the solar collector area and the mass flow rate of the solar loop on the solar fraction were investigated. The solar fraction was computed for 40 and 20 kW auxiliary heater capacity. The required solar collector area for optimum solar fraction was reduced from 140 to 88 m² with using 20 kW auxiliary heater and reduced to 46 m² with the 40 kW auxiliary heater using. The results proved that with the mass flow rate of the solar loop increasing from 0.18 to 1.5 kg/s the collector area required decreases from 110 to 60 m². This study was performed by the TRNSYS simulation using.

The purpose of this study is to perform an exergy analysis of a combined cooling, heating and power (CCHP) system driven by hybrid wind–solar–gas turbine. And use compressed air energy storage technology to solve the problem of network fluctuation caused by renewable energy instability. The triple supply system equipment proposed in this paper includes energy supply equipment, heat recovery equipment, cooling equipment and energy storage equipment. The energy balance model of the energy storage system is established, and the working characteristics are simulated by specific numerical values to find out the optimal design structure of the triple supply system, reduce the exergy loss of the equipment and improve the exergy efficiency of the system energy conversion.

Numerical studies have revealed the possibility of improving the energy supply of low-power energy consumers located in remote areas using local environmentally friendly renewable energy resources of small streams, wind surface layers of the atmosphere, and solar radiation.

Aspects of the use of the first experimental wind power plant with a capacity of 0.75 МW in the conditions of Tashkent oblast are considered. The results of monitoring of electric power development by the wind power plant for the months of 2017–2018 are presented. According to the monitoring data, the ratio of electric power production at the installation for the period from September 2017 to July 2018 was 714.9 МW h.