Advanced Materials Research Vols. 512-515

Abstract: This paper presents a method which combines an artificial neural network and a genetic algorithm (ANNGA) in determining the tilt angle for photovoltaic (PV) modules. First, a Taguchi experiment was used to perform an efficient experimental design and analyze the robustness of the tilt angles for fixed south-facing PV modules. Following, the results from the Taguchi experiment were used as the learning data for an artificial neural network (ANN) model that could predict the tilt angles at discrete levels. Finally, a genetic algorithm method was applied to obtain a robust tilt angle setting of the tilt angle of PV modules with continuous variables. The objective is to maximize the electrical energy of the modules. In this study, three Taiwanese areas were selected for analysis. The position of the sun at any time and location was predicted by the mathematical procedure of Julian dating; then, the solar irradiation was obtained at each site under a clear sky. To confirm the computer simulation results, experimental system are conducted for determining the optimum tilt angle of the modules. The results show that the seasonal optimum angle is 26.4 (deg.) for February-March-April; -9.47(deg.) for May-June-July, 21.32(deg.) for August-September-October and 53.13(deg.) from November-December-January in the Taiwan area.

Abstract: To develop and take advantage of solar energy resources in coral reefs, the paper discussed the problems about local solar resources, typhoon, corrosion, geology, transportations and installation. The analysis indicates that the typhoon-prone, serious corrosion and bad geology will cause many difficulties to installation and use of solar power equipments. Authors believe that, installing and using small solar power equipment in coral reefs is feasible, but the suitable measure of anti-typhoon, anti-corrosion, transportation, installation and maintenance must be accepted, which needs a great deal of budget support.

Abstract: This paper analysis on the international energy security situation and the energy consumption characteristics, and the proposals on international energy cooperation in China are put forward. With the sustained growth of energy consumption, fragile price system, intense conflict of energy politics, serious problems of energy and environment, the international energy security situation had been not optimistic. Due to the characteristics like large consumption, rapid growth, coal-based energy structure, low energy efficiency, high dependence on imports, serious environmental problems, increasing use of new energy and renewable energy, fruitful but troubled energy saving, required China to participate in international energy cooperation widely. In China international energy cooperation should be based on the principle of mutual benefit, technology sharing and dialogue & consultation, to ensure the conventional energy supply as fundamental goal, to develop and utilize new energy & renewable energy as direction, to establish energy-themed dialogue & communication as important pathway.

Abstract: To improve the efficiency of the power generation，the scheme of the solar tracking system is designed by analyzing the technical characteristics of the GPS positioning system. The microcontroller is chosen as the core which has realized the initiative sun-tracking to improve the efficiency of the power generation. The solar elevation angle and azimuth are calculated by extracting the GPS real-time datas. The position of the solar panels can be obtained through the angle sensor. Finally, adjust the orientation of the panels by the driving stepping motor to track the sun.

Abstract: Single-state grid-connected photovoltaic (PV) system has only one stage of power conversion and the control objectives needed to be considered simultaneously include synchronization with the utility voltage, harmonics reduction for grid-connected current and etc. Then the complexity of control strategy is increased. To deal with the characteristics, sliding mode controller is used to achieve the synchronization between grid-connected current and grid voltage and to control the waveform of grid-connected current, and the slide surface is designed based on PI method. Σ−Δ modulator is proposed to achieve the fixed switching frequency. Simulation results show that the system has good performance and the system is feasible.

Abstract: In this research we present a Lock-In amplifier photoluminescence image (PLI) detection system. Using a commercially available CCD camera, combined with a modulated excitation light source system, Lock-In amplifier technique is employed to enhance the sensitivity and signal-to-noise ratio of the image. Using a high resolution camera, we developed a high spatial resolution non-contact inspection system for solar cell. Each solar cell can be examined within 2s relevant for inline processing control.

Abstract: This paper provides proof of concept for a technique that uses high resolution thermal infrared imager to detect faults for outdoor operation photovoltaic array. An experimental study focused on two situations was tested: abnormal emitting heat of monocrystalline silicon solar cells (hot spot); open circuit fault of photovoltaic array. Experimental results show that the infrared image could clearly give prominence to the faulty solar cell or PV array. The back surface temperature of solar cell with hot spot is higher than normal ones with 13.2°C in mean value，and the back surface temperature of open circuit PV array is higher than normal ones with 2.8°C in mean value.

Abstract: The research team on solar energy of Institute of HVAC in Jiaxing University has made survey on solar energy enterprises in Jiaxing City since September 2009.The results of survey indicate, the quantities of solar company registered more than 1100 in Jiaxing city. All of the solar companies distribute in all counties in Jiaxing, but most solar companies concentrated in the Haining County. Jiaxing’s solar energy industry have formed a complete industry chain, including the rough tube production, the evacuated tube production, the water tank production, the sealing silicone ring production, the stand production, the getter production, the solar water heater and the solar energy project and so on. The solar energy industry also appears some difficulties at present in Jiaxing, In order to solve all these difficulties, the local government, the solar energy enterprises, the local colleges need to be union, and give advice and suggestions for the solar energy industry development in Jiaxing

Abstract: Er³⁺ ,Yb³⁺ :Y₂O₃ nanocrystal up-conversion material has been prepared using the sodium carbonate precursor method and doped in the P25 to prepare up-conversion nano-TiO₂ powder. The micromorphology, structure and particle size of the up-converting nanoparticles were characterized by atom force microscopy (AFM) and X-ray diffraction (XRD). Nano-TiO₂ powder with up-conversion performance was applied to Dye-sensitized solar cells, the photoelectric conversion efficiency of the DSSC with up-conversion material is twice the photoelectric conversion efficiency of normal DSSC irradiated by infrared light.

Abstract: It is widely accepted around the world that degree days should act as the measurement of HVAC energy in a given place. This paper makes use of the temperature data from 1985 to 2004 from 96 meteorological stations in Shaanxi Province. Based on the daily average temperature in some cities, counties and districts in Shaanxi, we work out the degree days. We divide different zones according to the normalized degree days from 1995 to 2004. In this paper, we analyze the distribution of degree days in Shaanxi, the changes in every decade, and the monthly distribution of degree days in Yulin, Yan’an, Xi’an, Hanzhong, as well as the changes of value in 20 years in Xi’an. At last, we figure out that Shaanxi has spread out its terrain in two climate zones: one is the cold zone; the other is the hot summer and cold winter zone. The HDD18 value has declined continuously in 20 years, and it drops 194.8°C•d/10a every year; meantime the CDD26 has ascended by 28.1°C•d/10a. In all the cities, the HDD18 value is the highest in January, and lowest in July. In the past 20 years in Xi’an, HDD18 value has dropped by 25.0°C•d/a, and the CDD26 has risen by 5.2°C•d/a, which are the highest among those cities.