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Copper indium diselenide (CuInSe2) compound was synthesized by reacting its constituent’s elements copper, indium and selenium in near stoichiometric proportions (i.e. 1:1:2 with 5% excess selenium) in an evacuated quartz ampoule. Synthesized pulverized compound material was used as an evaporant material to deposit thin films of CuInSe2 onto organically cleaned sodalime glass substrates, held at different temperatures (300–573 K), by means of single source thermal evaporation method. The phase structure and the composition of chemical constituents present in the synthesized compound and thin films have been investigated using X-ray diffraction and energy dispersive X-ray analysis, respectively. The investigations show that CuInSe2 thin films grown above 423 K are single phase, having preferred orientation of grains along the (112) direction, and having near stoichiometric composition of elements. The surface morphology of CuInSe2 films, deposited at different substrate temperatures, has been studied using the atomic force microscopy to estimate its surface roughness. An analysis of the transmission spectra of CuInSe2 films, recorded in the wavelength range of 500–1500 nm, revealed that the optical absorption coefficient and the energy band gap for CuInSe2 films, deposited at different substrate temperatures, are ∼104 cm−1 and 1.01–1.06 eV, respectively. The transmission spectrum was analyzed using iterative method to calculate the refractive index and the extinction coefficient of CuInSe2 thin film deposited at 523 K. The Hall effect measurements and the temperature dependence of the electrical conductivity of CuInSe2 thin films, deposited at different substrate temperatures, revealed that the films had electrical resistivity in the range of 0.15–20 ohm cm, and the activation energy 82–42 meV, both being influenced by the substrate temperature.

Abstract In this paper, the experimental performance of a 45 m2 solar field of non-tracking external compound parabolic (XCPC) collectors installed at the University of California, Merced is described. The solar field was operated during July-August 2020 in both clean and dirty conditions and at varying operating temperatures (70, 135, 170 °C) while operating an air heater, thermal evaporator, and double effect absorption chiller. Performance data was used to develop an instantaneous solar field performance model which was then incorporated into an annual performance model using TMY3 data to estimate yearly production from the solar field. The model predicts an annual generation of ∼1100 kWh/m2-year at 80 °C, ∼1000 kWh/m2-year at 100 °C, ∼900 kWh/m2-year at 120 °C, ∼800 kWh/m2-year at 140 °C, and ∼700 kWh/m2-year at 160 °C in California. The XCPC technology is currently expected to have an installed cost of $300/m2 and an annual operations and maintenance cost of $6.5/m2-year. Over a 25 year lifetime it provides a levelized cost of heat at 2–4 cents per kWhth delivered. This is below the cost of commercial natural gas in California and at temperatures ≤ 120 °C below the cost of industrial natural gas, which highlights the potential of the XCPC technology for decarbonizing thermal applications such as water and space heating, drying, sterilization, desalination, evaporation, low pressure steam, double effect absorption chilling, process heating, and more. The lifetime cost of emissions reductions is ∼$169 per metric ton of avoided CO2 when replacing natural gas, ∼$137/MT CO2 when replacing propane, and ∼$83/MT CO2 when replacing electric heating.

Abstract This paper presents information comparing three transparent plastic films with glass as glazings for solar energy absorption collectors. Data concerning the transmittance characteristics of these films are included, together with information concerning other physical properties such as tensile strength, index of refraction, and weathering characteristics.

Abstract Periodically adjusted parabolic mirror/evacuated tube absorber combinations are evaluated using computer simulation methods. The results show that a 4–6 X reflector adjusted 10–15 times per year, operating at 150°C, competes favourably in cost-effective terms with a fixed reflector CPC collector operating at 50°C. Periodically adjusted collectors are advocated for medium temperature industrial applications below 200°C.

Abstract Flux profiles of the sun image were measured at the focus of the California Institute of Technology lens-type solar furnace using NRDL water-cooled radiometers. A maximum flux value of 220 cal per sec per sq cm was recorded when the direct solar radiation received at the furnace site was 1.04 cal per min per sq cm. Under these conditions, the furnace operating efficiency was found to be 47.2 per cent. The losses of 52.8 per cent are ascribed to transmission losses in the lenses, reflectivity losses at the mirrors, the geometrical imperfection of the individual lenses and mirrors, and lack of perfect superposition of the nineteen sets of images.

Abstract The desalination of water is a process wherein the brackish water is purified by removing the salts. With increasing demand for fresh water, there is a vast scope for development of sea water desalination process. A number of methods exist for the desalination process, but solar desalination method promises to save energy in today’s energy crunch scenario. A novel solar desalination setup is proposed here. It uses an elliptic hyperboloid concentrator and a helical receiver along with a multi-tray desalination unit to purify water in the most effective manner. The helical receiver proposed in the present work aims at the Dean Flow effect in order to enhance heat transfer in laminar flow. The effectiveness of this property with respect to various physical parameters has been observed and an optimum design has been suggested based on this. The elliptic hyperboloid concentrator is a special design for concentrating solar radiation because of it offers to operate at high efficiency without the requirement of tracking. A detailed ray-tracing code was developed to simulate the radiation incident on the concentrator and an accurate estimation of the optical efficiency was made based on this. The two systems were integrated in order to arrive at a maximum output level for the solar desalination system as a whole.

Abstract The stable Ni(OH)2 ultrafine nanosheet combined with Bi2MoO6 to form heterojunction have been fabricated successfully by a simple and mild one-step solvent-thermal method. In this work, the Ni(OH)2/Bi2MoO6heterojunction increased the absorption range of visible light compared to the pure Bi2MoO6, from the UV–visible diffuse reflectance spectrum (DRS), thus greatly improving the degradation rate of organic dyes. The Ni(OH)2/Bi2MoO6heterojunctionwith different proportions was prepared by a mild one-step solvothermal method by controlling the mass fraction ratio between the nickel source and the bismuth source. The morphology and structure of the heterojunction materials were characterized by afield emission scanning electron microscopy (SEM) and a field-emission high-resolution transmission electron microscope (TEM). In this experiment, the photocatalytic properties were demonstrated by the degradation of organic dye Rhodamine B by the prepared samples. The results showed that 2%Ni(OH)2/Bi2MoO6 composite had the strongest photocatalytic performance and the maximum degradation rate was about 98% (135 min) when the Rhodamine B was degraded by visible light irradiation. It also can be found that Bi2MoO6composited by Ni(OH)2ultrafine nanosheet, compared with pure Bi2MoO6, the photocatalytic performance is improved by decreasing the recombination rate of photogenic carriers.

Abstract Significant efforts have been made to improve the performance of the Cu(In1-xGax)Se2 (CIGS) solar cells by tuning the band gap of the CIGS absorber to match it with the solar spectrum. However, the performance of the current record-holding CIGS solar cells is still far from theoretical expectations. Various researchers reported that the open circuit voltage (Voc) and the fill factor (FF) degrade in wide band gap CIGS solar cells. However, the limiting factors on further boosting the efficiency are still a matter of debate. In this study, we focus on tuning the properties of the interfacial layer between the rear contact and the wide-gap CIGS absorber to lower the contact resistance and recombination rate. Based on the numerical simulation using SCAPS (a solar cell capacitance simulator), we find that a MoO3 interfacial layer with high work function is more effective than its MoSe2 counterpart in reducing the back barrier, which in turn increases the Voc and the FF of the solar cell. We further predict that an overall efficiency of 24% can be achieved by reducing the back surface recombination and Schottky barrier with sub-micrometer a thick CIGS absorber. This work puts forward a strategy to improve the efficiency of wide band gap CIGS solar cells whilst reducing the raw materials consumption.