Vol 52, No 3 (2016)

The results of the studies of the spectral characteristics of terrestrial solar radiation carried out based on the calculation model for an index dependence of spectral air mass transmission coefficients relative to the standard solar radiation АМ-1.5 are presented for different air mass values. Spectral transmission coefficients for standard air mass АМ-1.5 relative to extraterrestrial solar radiation AM-0 are obtained by comparing the respective spectral intensities from the published literature. During the theoretical calculations, the limiting value of the air mass (for the solar disk near the horizon) is taken to be large by a factor of 36 than for air mass AM-1.

The numerical modeling of warm water displacement from an inclined tank of an integrated collector storage solar water heater was performed, connection schemes of two heaters and the location of a supply and an extraction pipes were compared. It was shown that the parallel connection of heaters provides the stability of the stratification and a higher heat pickup than the series one, and the diagonal layout of the pipes in a stratified tank is preferable. The picture of thermocline dissipation was studied and the strong influence of the displacing fluid temperature on the degree of stratification was shown.

The results of analyses of thermal stratification using different initial water temperature profiles are reported and discussed. Stratification proved to be the main factor in the cooling process, since although ambient temperature is also a determining factor, in this case it played a lesser role because the tank’s location inside the laboratory meant that it remained almost constant.

This article presents the results of the design studies intended to determine the impact of partial absorption and conversion to heat of solar radiation (SR) that penetrates translucent covers (TCs) of the housing of flat-plate solar collectors (FSCs) for heat transfer fluid (HTF) heating. These studies have served as the foundation for deriving the equation to find the value of the reduced effective coefficient of the heat losses into the ambient from the light-absorbing heat-exchange panel (LAHP) of the collector in question.

The article presents a method to determine local defects in solar photovoltaic cells (PVC). It is based on the non-contact measurement of PVC area temperature distribution by a special thermovision system when applying forward and reverse voltage to the cell. Distribution of PVC surface temperature is determined by nonuniformity of current density (because of local defects) and reveals itself in the intensity of thermal radiation in the infrared spectrum (IR). The difference between the light detector signals when applying a forward or reverse voltage to PV cells and in the absence of applied voltage to the PVC is used to eliminate the effect of IR light patch, surface irregularities emissivity of solar cells, heterogeneity sensitivity light detector array. The hardware and software implementation techniques using the focal plane array of infrared 3–5 micron spectral range and 320 × 256 elements size are presented.

The spectral dependences of heterostructures pSi–n(GaSb)_1–x(Si₂)_x (0 ≤ х ≤ 0.07) and nGaAs–p(InSb)_1–x(Sn₂)_x (0 ≤ х ≤ 0.05) alloyed by GaAs molecules are studied. The ionization energy of GaAs molecules in the studied structures is assessed and its dependence on the width of the band gap and parameter of the lattice of the basic semiconductor are found.

An accelerated method of aligning the center of the reflected light spot from an individual heliostat with the focal point of the concentrator by the alignment of the optical axis of the heliostat tracking sensors with the main optical axis of the concentrator is.

This article provides the results of design studies intended to determine the specific amount of heat accumulated in the inner layers of vast enclosures used in premises with an insulation passive solar heating system (Q_acc) by the temperature-wave method. As shown by the calculation data, the value of Q_acc depends significantly on the ratio of the F_te surface area of the translucent enclosure of the considered premise to the F_fl surface area of its floor slabs and the amplitude of air motion in the heated premise. According to the calculated data, Q_acc, at the end of the second decade of March, is 169.0 kJ/m² at F_te/F_fl = 0.30–0.40 whereas the coefficient of natural heat accumulation in the inner layers of the given vast enclosure is ≈0.12.

The influence of ultrasonic irradiation (USI) on the load characteristics of the In–n⁺CdS–nCdS_xTe_1–x–pZn_xCd_1–xTe–Mo heterostructure was studied under different illuminance levels of monochromatic light (λ = 632.8 nm) and white light. It was established that the efficiency of the heterostructure increases under the increase in the laser irradiation power and under the action of ultrasound.

This paper considers how the geographical and climatic factors and solar radiation conditions influence changes in the energy indicators of silicon solar cell photovoltaic modules using the example of arid territory.