Research Of High Concentrating Fresnel Photovoltaic/Thermal System

Solar energy is characterized by large scale reserves, wide distribution and cleaning.There is vast space for solar energy utilization, especially when energy crisis and environmental problems are extensively concerned by all over the world. The advantage of solar energy is more and more obvious. Photovoltaic technology is now mature and used in every aspect of social life, but it’s manufacturing process is in high pollution and the battery is in low efficiency. Concentrating photovoltaic technology can greatly reduce the use of photovoltaic cells. Besides, multi-junction concentrating battery is more efficient than ordinary crystal silicon cells. So the costs of high concentrated photovoltaic system is dramatically reduced.The basic principle and system composition of high concentrated Fresnel photovoltaic system is introduced in this paper. Two-axis tracking system and its tracking mode is introduced and discussed. To achieve better output performance, Photovoltaic system need to track its maximum power point all the time. Several most commonly used maximum power point tracking methods is listed in this paper.It is discussed when the tracking system applied in the high concentrated photovoltaic system. The advantages and disadvantages of different MPPT strategies is analyzed and contrasted.For high concentrated photovoltaic system, photosensitive tracking combined with apparent day trajectory tracking method would guarantee accurate and stable tracking of the sun. In the same time, it would insure the safety of the system.Although admittance incremental method costs slightly higher than other methods, but this method is stable and accurate and it’s more suitable for high concentrated photovoltaic system.The research of high concentrated photovoltaic system is mainly concentrated in the uniformity of energy flow and the design of the cooling system. Concentrated photovoltaic battery has good high temperature resistance and high radiation resistance. Under the condition of natural cooling at high magnification concentrator,the photovoltaic module can still keep high conversion efficiency. In order to make full use of solar energy, the integrated system of photovoltaic and solar-thermal can not only improve the efficiency of power generation, but also reduce the battery temperature and collect the heat energy.High magnification concentrated photovoltaic module is tested in a series of experiments. Module output performance varies when solar irradiance and the cell chip temperature and tracking deviation angle are changed. The relationship between moduleoutput and three factors is tested. Under the condition that two other factors are similar, the relationship between the single factor variety and module output characteristic is tested.When the concentrated multiple is fixed, the rise of direct irradiation power improves the module efficiency; The rise in the temperature of the battery chips reduced module efficiency.Tracking deviation angle for module has great influence on the output performance, when the deviation angle achieves one degree, module power relatively declines more than 50%.Considering the problem of low-temperature, water cooling module is easy to freeze in the northern winter, so forced air cooling heat dissipation system is put forward. Firstly the air-cooled module is installed on the concentrated photovoltaic module and is experimented.The cooling module is improved through the experimental results, while the heat dissipation effect is still not ideal. So the cooling module is modeled in 1:1 scale and the flow field is simulated in ANSYS. The best imported wind speed comes from the analysis of the calculation results and by analysis of the internal flow field, optimized model is confirmed.The optimized model is simulated and the best air-cooled module structure is determined.