• Energy Research
• CN close
• IN close
• AU close
• Solar Energy close

Abstract Solar chimney power plant (SCPP) is one of the promising power generation approaches for future applications of solar energy. An unsteady comprehensive mechanism model and a streamlined unsteady mechanism model of SCPPs are derived to analyze the energy conversion and transmission of the system in this paper. The streamlined unsteady mechanism model with concise expressions clearly indicates the correlations among the power output and geometric parameters. Both of the two models are verified by the experimental data from the Spain Manzanares demonstration plant. Moreover, a power quality factor is defined to evaluate the power generation quality of SCPPs both from the points of generation efficiency and power stability. The suitability of the geometric optimization of SCPPs based on the streamlined unsteady mechanism model is finally verified by an example. The coupling optimization results show that there are a strong positive correlation between the chimney height and the power quality factor, as well as a negative correlation between the solar collector radius and the power quality factor. Furthermore, the optimal solar collector height is a quadratic function relation with the chimney diameter, while the optimal thickness of the heat storage layer is little associated with other geometric parameters.

Abstract A solar-driven hybrid generation system (HGS) in an integrated design is successfully fabricated, which consists of a silicon thin-film solar cell (STC), thermoelectric generators (TEGs) and a heat collector. STC absorbs parts of the solar energy and directly converts it into electric energy. The undesired waste heat from STC and parts of the solar energy are collected by the heat collector and conducted to TEG to produce thermoelectric conversion. The structure and the performance of HGS are discussed. A numerical simulation is also performed on TEG to obtain the distribution of heat flux using finite element method (FEM). The results show that the performances of TEG and STC are synchronously enhanced due to the integrated design. Especially the heat flux on the hot side of TEG integrated in HGS increases by more than tenfold. The total generated power of 393 mW is obtained in HGS, which is twice larger than that of single STC. The developed HGS is a promising power system which can effectively broaden the use of the solar spectrum and increase the power output in solar conversion.

Abstract ZnO films with excellent photoelectric properties have been realized in this study through low-concentration F-and-Al co-doping, conducted with radio-frequency magnetron sputtering. It has been demonstrated that the valence state of Al gradually changes from the incomplete oxidation state to the oxidation state, though the chemical valence states of F, O, and Zn are stable. The as-prepared films possess good performance with a mobility of ∼41.89 cm2/Vs, resistivity of ∼3.50 × 10−4 Ω cm, and an average transmittance over 90% in the range of 400–1200 nm. Moreover, the crystallinity of the films and effect of Al doping were further improved through post annealing. Consequently, the improved film mobility, carrier concentration, resistivity, and sheet resistance were, respectively, measured as 53.97 cm2/Vs, 5.18 × 1020 cm−3, 2.23 × 10−4 Ω cm, and 2.73 Ω/□. These films are, therefore, superior to the commercial F-doped SnO2 (FTO) and comparable to the Sn-doped In2O3 (ITO) films. High-performance perovskite with a conversion efficiency as high as 16.24% was achieved when the abovementioned optimized film was used as the front electrode. The reference perovskite solar cells that had commercial ITO and FTO as their front electrodes showed lower efficiency of 15.92% and 12.45%, respectively.

Abstract A combination of heat pump and humidification-dehumidification (HDH) process is a suitable choice to obtain fresh water for small-scale desalination applications, especially when the solar energy is used as the auxiliary heat source. In this paper, a novel two-stage solar assisted heat pump (SAHP) desalination system based on HDH, in which the humidifiers are connected in parallel, is proposed. A mathematic model is developed to improve the system performance by optimizing the operating parameters such as process air flow rate and cooling seawater flow rate, and it is also validated by the experimental results. Analysis results indicate that there exists an optimal process air flow rate in the desalination system, which does not vary with the hot seawater flow rate. However, it will be increased with the increase of cooling seawater flow rate. When the flow rates of process air and cooling seawater are 350 m3/h and 0.55 m3/h, respectively, the maximum fresh water yield is 17.94 kg/h. The corresponding gained-output-ratio (GOR) is 2.02. However, the system performance is constrained by a bottleneck: increasing dehumidifying capacity can result in a reduction in the performance of lower-temperature (LT) humidifier. Consequently, a modified system is then proposed to solve this bottleneck effectively. The maximum fresh water yield can be increased by 16.70% to 20.54 kg/h, and the corresponding maximum GOR is also increased by 18.05% to 2.42.

Abstract In this article, we have studied an identical section of a core-shell ZnO Nanorod (NR) based lead-free perovskite solar cell. Various factors affecting the solar cell’s performance have been rigorously investigated for device optimization; specifically, the length and diameter of the ZnO NR core, perovskite shell thickness, thickness of perovskite cap layer, and hole transport layer (HTL) thickness. The defect density of states (DOS) in the perovskite absorber layer and the effect of interface defect density on the performance of the cell are also studied. We obtained power conversion efficiency (PCE) of 14.50%, the open-circuit voltage (VOC) of 0.96 V; short-circuit current density (JSC) of 18.11 mA/cm2 and Fill factor (FF) of 83.35%. We also analyzed the effect of tilt or inclination of NR on the performance of the cell which is a crucial factor toward achieving high performance. By optimizing the device parameters, we have achieved a PCE of 21.27%, VOC of 0.97 V, JSC of 29.56 mA/cm2, and FF of 84.15% at an inclination of 10-degree tilt with respect to the incident light under AM 1.5 illumination. The shadowing mechanism behind efficiency droop is also presented to further realize an optimal design high-performance PSC.

Abstract The values of series and shunt resistances play an important role in the modelling behaviour of a photovoltaic cell. The authors proposed in earlier work a new method to determine these values numerically at maximum power point using the Newton–Raphson method and equations based on the Lambert W -function. Here, an experimental investigation has been carried out to further validate this method and observe its behaviour over the entire current–voltage curve. Current–voltage curves from a single multi-crystalline cell were obtained under outdoor testing in Hamilton, New Zealand under three levels of illumination (800, 900, and 1000 W/m 2 ). In addition to the method of Ghani and Duke (2011) , two other methods were also used to calculate series and shunt resistances based on the parameters extracted from the experimental data. A comparative study of each methods output current vector using a root mean square error analysis revealed that greatest accuracy was achieved with the proposed approach.