Applications of solar energy to power stand-alone area and street lighting

A stand-alone solar-powered street or area lighting system is designed and operated completely independent of the power grid. The equipment and maintenance costs associated with a stand-alone solar-powered system are compared with the cost of using electricity to run grid connected street lights. The project focused on the viability of using solar energy to power the lights in the area surrounding St. Louis, Missouri. The results had to be consistent to warrant converting new areas to independent solar powered lighting. A prototype system is constructed from equipment available on the market for the purpose of gathering data on different lighting sources. The prototype uses a 100W high pressure sodium lamp, 165W solar panel, a maximum power point tracker, an inverter, and lead acid gel batteries. The system has the design capability to last for four days of overcast skies and generate around 9500 lumens of brightness. The results are used to determine the size of the panel and the number of batteries required to guarantee that the lamp would work a preset number of days without failure. Real-life data collected by the prototype system and verified by computer simulations were used to evaluate the long-term performance of the system. An economic analysis is also performed to determine if the project is cost effective --Abstract, page iii

Efficiency Analysis and Comparative Study of Hard and Soft Switching DC-DC Converters in a Wind Farm

This paper focuses on efficiency analysis and comparative study of hard-and soft-switching dc-dc boost converters in wind farms. The efficiency of an ac or a dc-based wind farm is dependent on the efficiency of its key components such as dc-dc converters. The demand for dc-dc converters depends on how voltage fluctuations are adjusted. This paper analyzes the efficiency of the switching method used in dc-dc converters. The switching and conduction losses of all the components of the dc-dc converters are modeled and the efficiency is calculated accurately. The power rating vs. efficiency of the dc-dc converters is also considered. The efficiency of the converter in soft switching mode is greater than in hard switching mode. The efficient operation of the converter at a given power rating is shown graphically