Optimization Design Of High Concentrating Photovoltaic Power Plants

High concentrating photovoltaic (HCPV) technology largely reduces the usage of semiconductor materials by concentrating the sunlight on high efficient solar cells with optical devices. Since the performances of the HCPV system is rather sensitive to the angle between the incident sun light and the normal of the solar panel, it is crucial important to use the accurate solar tracking system in HCPV system, which enhances the complexity of HCPV power generator as compared to the conventional photovoltaic system based on silicon materials. However, the practical field performances of the HCPV power generator has been much less investigated as compared to conventional silicon based photovoltaic system. How to optimize the structure of the HCPV system as well as the solar tracking system in order to maintain a general high field performance of the HCPV system according to the practical environmental conditions still remains as crucial issues to the field of HCPV. The present thesis mainly discusses about the design and field operation of the HCPV power systems, and several cogent optimization strategies for both the structure of HCPV generator and the solar tracking system have been provided.Firstly, the layout distribution of the individual HCPV power generators has been discussed. The layout distance between each individual HCPV influences the general performance of the HCPV power plant:using too large layout distance increase the occupation area of the power plants and enhances the usage of the cable for electronic connections, while using too small layout distance results in the mutual occlusion among different HCPV power generators. Herein, the layout distribution has been optimized using simulation approaches such as the coordinate rotation transform model and solar battery equivalent circuit simulation model. According to the practically measured solar radiation conditions, the annual energy outputs by the HCPV power plant as a function of the layout distance of the individual power generator units have been simulated. The optimum layout distance has been used for the further practical construction of the HCPV power plants.Apart from the layout distribution, the solar tracking strategy also influences the performance and stability of the HCPV system. Herein, the correlation between the solar tracking frequency and the performance of the HCPV power plants has been mainly investigated. The tracking mismatch angle and the respectively induced energy loss during the photovoltaic process have been simulated for each specific solar tracking frequency. Accordingly, a new solar tracking strategy using variable tracking frequency according the practical solar movement has been developed. As proposed tracking strategy significantly reduces the tracking motions and improves the reliability without reducing the performances, as compared to the conventional solar tracking approaches using a constant solar tracking frequency.Based on the above considerations,44.5 kW ground HCPV power generators and 80.5 kW rooftop HCPV generators have been practically constructed and their field performance has been practically observed from a completely year. How environmental parameters, such as solar irradiance, ambient temperature, wind speed and obscured by clouds, influence the performance from both energy conversion and power inversion aspects have been analyzed. Large variations in performance of the HCPV system have been observed for different months, due to the respective changes in the environmental parameters. The direct normal irradiance level has been found to be a dominate parameter that mainly determines the amount of energy production as well as the performance ratio of the HCPV system. The environmental temperature and wind velocity have less influence on the system performance ratio than expected. A quantified correlation between the output power and the direct normal irradiance has been derived, which provides guidelines for both the cogent application and the modeling of HCPV techniques for grid-connected power generation.