Investigation Of Concentrating Photovoltaic System

Under the situation of the worldwide energy crisis and environmental pollution, people are eager to use renewable energy sources to replace the limitation and pollution conventional energy sources. Solar energy is the most abundant renewable energy, it is widely distributed, renewable, no pollution, and is recognized as an ideal alternative energy sources. The photovoltaic (PV) electricity generation has an important position in the utilization of solar energy, it has a huge development in recent years. However, due to expensive material and complicated process of manufacture, large-scale application is not easy to attain. Many countries are exploring new methods to reduce the cost of photovoltaic generation, and the concentrating photovoltaic system is an effective way.This article analyzed the major components of concentrating PV system, designed a completed concentrating PV system, and investigated the PV cell output characteristics with concentrator and without by experiment and numerical simulations.First, the shape, principle and optical path of concentrators such as dish concentrator, CPC concentrator and Fresnel lens were analyzed and the concentrating effect of concentrators was simulated. Compared those results, Fresnel lens was selected as the concentrator of concentrating PV system, because of its good environmental adaptability, lightweight, abundant sources of material, low cost, easy manufacturing, and so on.Second, a two-dimensional solar tracking system was designed, which consisted of a PSD sensor, microprocessor and step motors. The microprocessor was as the core to control the operation of the system, a high-precision photoelectric sensor was used to obtain the location information of the sun and then the processor would control the step motors'movement with the aim of tracking the sun. It is confirmed through experiments that the system can accurately track the sun.At last, the performance prediction of concentrating PV modules was performed. For a solar concentrator with aperture area of 1m2, the efficiency and power output of a concentrating PV module was calculated for various temperatures and concentration ratios. The study was then extended to calculate the temperature, efficiency and power output of the PV module at various concentration ratios and velocities of cooling water. The distributions of current on cell surface were simulated and the output characteristics of solar cell with the designed concentrating PV system were investigated experimentally.The results showed that the output power and efficiency of cells were increased significantly with a concentrator.