Solar Power Output Correlation With Utility Demand in Southern Nevada

Abstract

Various solar electric system performance codes are used to predict the power generated by different solar power systems in the Southern Nevada area during 1990 by using the National Solar Radiation Data Base (NSRDB) for Las Vegas. The system types evaluated along with the prediction codes (shown in parenthesis) are as follows: a central receiver or a power tower system with various amounts of storage (SOLERGY), a Luz-type SEGS parabolic trough system without fossil fuel backup or storage (LUZERGY), a dish-Stirling system (DISH2, a conversion of direct beam radiation with constant collector/engine efficiency was used for this), and various arrangements of nonconcentrating photovoltaic devices (PVFORM). Comparisons of these results are made with the daily variations of load requirements of an electrical utility operating in the same geographical area. These comparisons are made for summer and winter periods. It is shown that several of the power generation schemes have summer peak outputs that occur at times very near to, but not coincident with, the peak utility load requirements. The power tower with a relatively small amount of thermal storage was the only scheme able to provide full power output at the times of summer peak demands. Winter peaks in this region occur during the night. Two comparisons are made that illuminate the summer load serving capability of solar generation in addition to simply showing time-variations of outputs. Included in these comparisons are the determination of the difference in time between the peak power output and the peak demand, as well as the normalized fraction of the peak power generated at the peak demand times.