Advanced Materials Research Vols. 805-806

Abstract: Magnesium fluoride (MgF₂) thin films were deposited by electron beam evaporation method and then films were bombarded by oxygen ions for various time to study the evolution of optical properties as a function of bombardment time. The transmittance, structure and morphology of films were measured by UV-vis spectroscopy, XRD and metallographic microscope, respectively. The mean transmittance of films in the visible range decrease significantly with an increase of bombardment time.

Abstract: This paper mainly discusses the mathematical model of the solar cell and it I-V characteristic curve equation , discusses the the relationship between parameters. When changes of light intensity and temperature,We uesed measured value for the reference data , the value of ,,,are tested in 25°C,1000W/m2 the battery is the 3909 battery of Suntech. Then we given the Calculate value of ,,,in 25°C,800W/m2, 200W/m². We uesed measured value for the reference data , the value of ,,,are tested in1000W/m², 30°C, the battery is the 4209 battery of Suntech. then we given the Calculate value of ,,,in 40°Cand60°C. Finally ,we analysised the change of the four parameters with light intensity and temperature changes, it shows that the calculation results is consistent with the test data. It can reflect the relationship between I-V characteristic and the changes of light intensity and temperature. This study will help us to give the I-V characteristic and data directly , also help us to study solar cell easyly in any environment

Abstract: The solar optical collector based on rotary parabola mirror for solar optic fiber lighting is discussed in this paper. By this reflection method, the chromatic aberration can be avoided. The performance of solar collecting and fiber coupling are simulated by Tracepro software. The results showed this system can collecting soar lights with high efficiency and has high light concentration ratio. The solar lights can be coupled into optic fiber with low loss. An interesting results is found that the concentration ratio decreased with the increased curvature ratio between ellipsoid surface and parabola surface.

Abstract: To diminish the effect of photovoltaic (PV) randomization on the power system, combining attribute reduction of rough set with support vector machine (SVM) regression theory, this paper applies SVM regression to directly forecast the output of the PV array, and is based on setting rough set as front-end processor and attribute reduction of historical data. According to the type of forecasting day, this paper selects multiple reasonable similar days (SD) from historical data and uses RS-SVR model to make predication. After repeated accuracy verification, the text used radial basis function as kernel function, and use parametric search and cross-validation method to determine the parameters. Finally, this paper compared average relative error of the RS-SVR forecasting model and SVR forecasting model, and verified that the RS-SVR forecasting model can effectively solve the problem of PV power output forecasting and obtain satisfactory results.

Abstract: The energy consumption in residential sector is increasing rapidly these years in China. The searching for a substitute for fossil energy sources has increased the interest in photovoltaic (PV) system as a friendly and reliable energy technology. In this study, as a promotion policy for PV system, the suitable feed-in tariff (FIT) rates are calculated assuming the cost payback time is within twenty years. Five cities, Harbin, Beijing, Shanghai, Kunming and Guangzhou located in different climate areas in China are selected for study. According to the simulation results, except Shanghai, the optimal FIT rate is close to the grid electricity rate especially in Beijing when there is no subsidy; on the other hand, the optimal FIT rates based on a 1/3 subsidy are less than the situation without a subsidy especially in Shanghai, the optimal FIT rate even reaches to zero when partly access to the grid.

Abstract: Liquid dehumidification air-conditioning system is a promising air-conditioning system as it is environment-friendly, capable of utilizing low grade heat and less dependent on the electric power. However, because of the heat waste, its performance is not yet as competitive as vapour compression system. To improve, a photovoltaic driven system is proposed in this paper: electricity is applied to regenerate desiccant; the electric energy comes from solar power. Performance analysis has been made. The results show the coefficient of performance of the new system is influenced by the concentration of the desiccant and can approach 6 at certain circumstances. It also shows that LiBr solution is more favorable among three common used desiccants. Moreover, this paper presents the new progress of experimental research on this system.

Abstract: Zinc oxide (ZnO) thin film was deposited on the glass substrate and cadmium-sulfide (CdS) thin film at room temperature by using an in-line pulsed-DC magnetron sputtering system. The sputtering process was carried out at various pulsed-DC power and radio frequency (RF) power from 400 W to 1 kW. From the thickness of the sputtered ZnO films, it was possible to obtain much higher deposition rate in case of pulsed-DC sputtering than RF sputtering. However, for both pulsed-DC sputtered and RF sputtered ZnO films, the similar results were obtained in case of the energy band gaps and the structural characteristics such as adhesion to CdS. From the results, the ZnO films sputtered by pulsed-DC power are expected to be used in the fabrication process instead of RF power.

Abstract: Ag nanoparticles arrays were fabricated by self-assembly method to accommodate manufacturing process of traditional silicon solar cells. Surface morphologies of films (5-27.5 nm) after annealing treatment with 260 °C and 400 °C were analyzed. The results showed that annealing temperature has important impact on self-assembled nanoparticles arrays. The tuning function of SiN_x dielectric film was also analyzed. The absorption peak generates a redshift with the maximum range about 100 nm in the absorption spectrum, and the peak widths become wider with the increase of thickness of SiN_x dielectric film for the same particle size distribution of Ag nanoparticles arrays.

Abstract: Grid-connected PV power station is one of the most important applications of photovoltaic system, generating low cost and high-quality electric power without non-renewable energy, as well as relaxing the tightness of daytime power demand. In China, it is usually installed on remote open area for low cost to guarantee the abundant solar power. However, this kind of place usually comes with tough weather conditions. In this paper, the property of the PV test field is estimated by its output characteristic. One inevitable and two avoidable reasons which affect the plant output are proposed. Firstly, the inevitable factor is weather, and the assessment analyzing the performance of PV power system under different weather conditions, such as sunny, cloudy, rainy and snowy is then presented. Secondly, losses owing to the mounting type and partial shading, which can be reduced by well designing and installing, are also mentioned and analyzed.

Abstract: Increasing concerns about reliable supplies and envi­ronmental consequences of petroleum-based fuels have made it important to develop sustainable green sources for liquid transportation fuels. One such source is cellulosic biomass. However, high costs associated with transportation and storage of low-density cellulosic biomass has hindered large-scale, cost-effective manufacturing of cellulosic biofuels. Ultrasonic vibration-assisted (UV-A) pelleting can increase biomass density, improve storability, and reduce transportation costs. This paper reviews the state of the art of this technique, covering the effects of different process parameters on pellet quality, pellet charring, pellet crack, and sugar yield. It can be concluded that pellet density increases with an increase in ultrasonic power and pelleting pressure, and with a decrease in biomass moisture content and particle size. However, large ultrasonic power may lead to the charring of cellulosic biomass, which adversely affects the conversion of cellulosic biomass to ethanol. In addition, some problems associated with UV-A pelletingof cellulosic biomass are proposed.