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Abstract In this work, earth-abundant CZTSSe thin film solar cells were fabricated by sulfo-selenization of the Mo/Zn/Cu/Sn/Cu metallic precursors. The influences of morphological and compositional properties of the absorbers on performance of solar cells were investigated by tuning Cu content in the films. The Raman analysis showed that absorbers consist of a kesterite CZTSSe phase with ZnSe as a minor secondary phase. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surfaces are Cu depleted and Zn enriched compared with the bulk composition of the absorbers. The results indicate that during sulfo-selenization the Cu diffused into the film and the Zn towards the film surface. The performance of the solar cells initially improved with the increasing of the Cu content and then decreased. By tuning the Cu content in the absorbers, the minority-carrier life time improved from 0.8 to 1.6 ns. The power conversion efficiency increased from 5.1 to 8.03% with fine controlling of Cu composition of the CZTSSe absorbers. The diode-ideality factors are higher than 2, suggesting an increased interfacial recombination in the devices. The high ideality-factors A and low minority carrier life times may originate from surface and bulk related defects, which in turn limits the Voc and the achievable high conversion efficiency for the CZTSSe thin film solar cells.

Abstract In this work, earth-abundant CZTSSe thin film solar cells were fabricated by sulfo-selenization of the Mo/Zn/Cu/Sn/Cu metallic precursors. The influences of morphological and compositional properties of the absorbers on performance of solar cells were investigated by tuning Cu content in the films. The Raman analysis showed that absorbers consist of a kesterite CZTSSe phase with ZnSe as a minor secondary phase. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surfaces are Cu depleted and Zn enriched compared with the bulk composition of the absorbers. The results indicate that during sulfo-selenization the Cu diffused into the film and the Zn towards the film surface. The performance of the solar cells initially improved with the increasing of the Cu content and then decreased. By tuning the Cu content in the absorbers, the minority-carrier life time improved from 0.8 to 1.6 ns. The power conversion efficiency increased from 5.1 to 8.03% with fine controlling of Cu composition of the CZTSSe absorbers. The diode-ideality factors are higher than 2, suggesting an increased interfacial recombination in the devices. The high ideality-factors A and low minority carrier life times may originate from surface and bulk related defects, which in turn limits the Voc and the achievable high conversion efficiency for the CZTSSe thin film solar cells.

Abstract There are instances in remote areas where heat is being wasted, e.g., in internal combustion, engines, etc. Some of this heat can be recovered to produce distilled water in solar stills. The solar still replaces the cooling tower, ponds, or radiators normally used to control the engine temperature. The diesel cooling water in such a system remains separate from the saline water in the solar still. The advantages of using such a system compared with a conventional solar still are: 1. (a) water costs are very much reduced 2. (b) the area occupied is much less, i.e., about 1 5 th 3. (c) production has much less seasonal variation 4. (d) the efficiency of the solar still is improved due to the higher operating temperatures. From experiments conducted at Highett using a Mk VI solar still fitted with a simple heat exchanger and a separate electrically-heated source of hot water to simulate the waste heat, design data are not available for application to working systems. The information required to match a solar still to a diesel's cooling requirement is: 1. (a) engine efficiency 2. (b) hourly fuel consumption 3. (c) hourly solar radiation 4. (d) hourly ambient temperatures. A by-product of this work has been the production of a “solar water heater” which costs less than that of the cheapest conventional system. This “solar” hot water system uses a heat exchanger similar to what is used to transfer the waste heat to the saline water. It is envisaged to have hot water productions approximately the same as the distilled water productions. The influence of hot water production on the output of the waste heat solar still is discussed.

Abstract There are instances in remote areas where heat is being wasted, e.g., in internal combustion, engines, etc. Some of this heat can be recovered to produce distilled water in solar stills. The solar still replaces the cooling tower, ponds, or radiators normally used to control the engine temperature. The diesel cooling water in such a system remains separate from the saline water in the solar still. The advantages of using such a system compared with a conventional solar still are: 1. (a) water costs are very much reduced 2. (b) the area occupied is much less, i.e., about 1 5 th 3. (c) production has much less seasonal variation 4. (d) the efficiency of the solar still is improved due to the higher operating temperatures. From experiments conducted at Highett using a Mk VI solar still fitted with a simple heat exchanger and a separate electrically-heated source of hot water to simulate the waste heat, design data are not available for application to working systems. The information required to match a solar still to a diesel's cooling requirement is: 1. (a) engine efficiency 2. (b) hourly fuel consumption 3. (c) hourly solar radiation 4. (d) hourly ambient temperatures. A by-product of this work has been the production of a “solar water heater” which costs less than that of the cheapest conventional system. This “solar” hot water system uses a heat exchanger similar to what is used to transfer the waste heat to the saline water. It is envisaged to have hot water productions approximately the same as the distilled water productions. The influence of hot water production on the output of the waste heat solar still is discussed.

Abstract In this paper, a hybrid features based support vector machine (SVM) model is proposed using infrared thermography technique for hotspots detection and classification of photovoltaic (PV) panels. A novel hybrid feature vector consisting of RGB, texture, the histogram of oriented gradient (HOG), and local binary pattern (LBP) as features is formed using a data fusion approach. A machine learning algorithm SVM is employed to classify the obtained thermal images of PV panels into three different classes (i.e., healthy, non-faulty hotspot, and faulty). The comparison of different machine learning algorithms and datasets is also carried out to validate the superiority of the proposed model and hybrid feature dataset. The experimental results reveal that the proposed hybrid features with SVM resulted in 96.8% training accuracy and 92% testing accuracy with lesser computational complexity and storage space than other machine learning algorithms. The proposed approach is easily implementable for efficient monitoring and fault diagnosis of PV panels.

Abstract In this paper, a hybrid features based support vector machine (SVM) model is proposed using infrared thermography technique for hotspots detection and classification of photovoltaic (PV) panels. A novel hybrid feature vector consisting of RGB, texture, the histogram of oriented gradient (HOG), and local binary pattern (LBP) as features is formed using a data fusion approach. A machine learning algorithm SVM is employed to classify the obtained thermal images of PV panels into three different classes (i.e., healthy, non-faulty hotspot, and faulty). The comparison of different machine learning algorithms and datasets is also carried out to validate the superiority of the proposed model and hybrid feature dataset. The experimental results reveal that the proposed hybrid features with SVM resulted in 96.8% training accuracy and 92% testing accuracy with lesser computational complexity and storage space than other machine learning algorithms. The proposed approach is easily implementable for efficient monitoring and fault diagnosis of PV panels.

Abstract In this paper, we report on the use of molecular level interaction between a composite poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) and graphene oxide (GO) hole transport layer (HTL) to improve the long term stability and performance of poly(3-hexylthiophene): poly(3-hexylthiophene): 3′H-cyclopropa [8,25] [5,6] fullerene-C60-D5h(6)-3′-butanoic acid 3′-phenyl methyl ester (P3HT: PCBM)-based bulk heterojunction organic solar cells (OSCs). The device employing this composite HTL demonstrated a maximum power conversion efficiency (PCE) of 4.82% with good reproducibility and retained over 30% of its initial PCE without encapsulation after 15 days under atmospheric conditions. This was a significant improvement compared with devices fabricated with either single GO or PEDOT: PSS HTLs, which retained only 26% and 0% of their initial PCE values of 3.16% and 4.00%, respectively. Hence, we imagine that this air resistant HTL composite will probably contribute significantly to the widespread commercialization of low cost and easily fabricated OSCs.

Abstract In this paper, we report on the use of molecular level interaction between a composite poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) and graphene oxide (GO) hole transport layer (HTL) to improve the long term stability and performance of poly(3-hexylthiophene): poly(3-hexylthiophene): 3′H-cyclopropa [8,25] [5,6] fullerene-C60-D5h(6)-3′-butanoic acid 3′-phenyl methyl ester (P3HT: PCBM)-based bulk heterojunction organic solar cells (OSCs). The device employing this composite HTL demonstrated a maximum power conversion efficiency (PCE) of 4.82% with good reproducibility and retained over 30% of its initial PCE without encapsulation after 15 days under atmospheric conditions. This was a significant improvement compared with devices fabricated with either single GO or PEDOT: PSS HTLs, which retained only 26% and 0% of their initial PCE values of 3.16% and 4.00%, respectively. Hence, we imagine that this air resistant HTL composite will probably contribute significantly to the widespread commercialization of low cost and easily fabricated OSCs.

Abstract This paper focuses on theoretical and experimental analysis used to establish the limiting heat flux for passively cooled thermoelectric generators (TEG). 2 commercially available TEG’s further referred as type A and type B with different allowable hot side temperatures (150 °C and 250 °C respectively) were investigated in this research. The thermal resistance of TEG was experimentally verified against the manufacturer’s specifications and used for theoretical analysis in this paper. A theoretical model is presented to determine the maximum theoretical heat flux capacity of both the TEG’s. The conventional methods are used for cooling of TEG’s and actual limiting heat flux is experimentally established for various cold end cooling configurations namely bare plate, finned block and heat pipe with finned condenser. Experiments were performed on an indoor setup and outdoor setup to validate the results from the theoretical model. The outdoor test setup consist of a fresnel lens solar concentrator with manual two axis solar tracking system for varying the heat flux, whereas the indoor setup uses electric heating elements to vary the heat flux and a low speed wind tunnel blows the ambient air past the device to simulate the outdoor breezes. It was observed that bare plate cooling can achieve a maximum heat flux of 18,125 W/m2 for type A and 31,195 W/m2 for type B at ambient wind speed of 5 m/s while maintaining respective allowable temperature over the hot side of TEG’s. Fin geometry was optimised for the finned block cooling by using the fin length and fin gap optimisation model presented in this paper. It was observed that an optimum finned block cooling arrangement can reach a maximum heat flux of 26,067 W/m2 for type A and 52,251 W/m2 for type B TEG at ambient wind speed of 5 m/s of ambient wind speed. The heat pipe with finned condenser used for cooling can reach 40,375 W/m2 for type A TEG and 76,781 W/m2 for type B TEG.