Vol 53, No 4 (2017)

The spectral dependences of photosensitivity of pSi-n(Si₂)_1–x–y(Ge₂)_x(ZnSe)_y heterostructures and structural features of epitaxial film of (Si₂)_1–x–y(Ge₂)_x(ZnSe)_y solid solution were studied by atomic force microscopy. The peaks of sensitivity at photon energies of 1.60, 1.85, 2.40, and 2.54 eV due to ZnSe and Ge quantum dots in the solid solution layer were revealed.

We have studied the electric current characteristics of a monocrystalline silicon solar cell (SC) at various solar radiation power levels from 0.05 kW/m² to 1 kW/m² (АМ1). It has been found that the energy efficiency of the SC increases from 9.5 to 15% with an increase in the power of radiation. The series resistance and shunt resistance of the SC decrease, which is associated with the modulation of the photoactive layers of SC.

The main provisions of the developed numerical unsteady model of the flat plate solar collector–storage tank (SC–ST) system are given. The model takes into account all of the main parameters of the SC (receiver parameters, radiative properties of the transparent fence for solar radiation, and thermophysical properties of the thermal insulation of the bottom) and the ST (thermophysical parameters of thermal insulation). An algorithm and a program for calculating the thermal properties of a closed SC–ST system have been developed based on this model in the Delphi language. The results of the calculated estimates of the time variation of water heating temperatures in the ST and the efficiency of the closed SC–ST system as a function of the ST volume are given for the case where the water temperature at the SC inlet is equal to the mean water temperature in the ST. The model and the program also make it possible to determine the time variation of temperatures of SC elements and water in individual sections along the length of the SC as well as the thermal losses of the SC sections. The model makes it possible to estimate the effect of the thermal properties of SC elements and the water velocity on the thermal properties of the SC–ST system. The program can be modified for the case of the open SC–ST system, i.e., where the water temperature at the SC inlet does not depend on the water temperature in the ST.

The results of numerical research on the determination of the temperature value of the internal surface of the heat-removing channel (HRC) walls of the light-absorbing heat-exchange panels (LAHPs) with the tubeon- sheet and thin-parallelepiped form of flat-plate solar water-heating collectors (FPSWHCs) are presented. The research method is based on compilation of the system of the balance equations for the light-absorbing plate (LAP) and HRCs of the LAHPs of the studied types and their designs with respect to the desired parameter. A practical example of calculation of the determination of the temperature value of the internal surface of the HRC wall of the tube-on-sheet LAHP, where the results of experimental research on the determination of the specific thermal efficiency of the mean-quality FPSWHC in full-scale terms, as well as laboratory and numerical research on determination of the optical and thermotechnical indicators of the copper tube-on-sheet LAHP.

By means of chemical vapor deposition (CVD) in a quasi-closed space with the use of a separate vaporizer, indium and tin oxides (ITOs)/glass structures with high conductivity and transparency and a thickness of up to 3 μm are obtained; they are suitable for the manufacture of protective coatings of mirrors with a reflecting facial layer.

Decomposition reaction of monosilane in glow discharge plasma of both direct (DC) and alternating current (AC) have been performed. The possibility of nanosilicon synthesis using the glow discharge plasma has been shown. The Raman spectroscopy is applied to study the phase composition and granulometric analysis of the obtained nanosilicon samples. The possibility of the structure and size control of amorphous silicon films with nano crystalline inclusions (a-Si:H/c-Si + nc-Si) by varying pressure and composition of a gas mixture in the process of synthesis has been demonstrated.

The technique for calculating the start and end times and the direct sunlight illumination period is described. The cumulative solar radiation (SR) falling on the front surface of translucent enclosures (TE) of heated premise (HP) is found. The final design results are based on processing 4-year generalized data from the Parkent weather station.

A brief summary of data collection and the creation of an actinometric database necessary for estimation of the solar energy potential of the Republic of Uzbekistan is provided. The results of the processing of four-year data from six meteorological stations of the Republic are presented in a graph form.

The concept of distributed energy of renewable energy sources is becoming increasingly popular. It is not simply supplementary but a real alternative to the conventional power supply from centralized power grids. Distributed electricity generators integrated into the Unified Energy System are a complex system in which the relationship between the observed parameters and the system state is ambivalent and ambiguous. Therefore, the approach to management in automatic control systems based on control of the output parameters is inappropriate in nature. In this case, the elaboration of a control action should be carried out on the basis of data on the current state of the object of control. Issues of the grid connection of distributed generators and control of their process parameters are considered.