Computer simulation of the operations of utility grid connected photovoltaic power plants

In order to evaluate the commercial viability of photovoltaic power systems it is necessary to have reliable estimates and descriptions of the supply of electricity generated by the solar technology, the demand for that electricity, and the market application. A methodology which produces information on performance, cost, and value components of utility grid connected photovoltaic power plants has been developed to assist in these evaluations (References 1,2). This report describes that analytical model and presents an application to a utility grid connected central power system with a range of operations alternatives. The Lifetime Cost and Performance (LCP) model is designed to causally relate the effect of hourly weather conditions and component efficiencies, system design, electrical design, long run effects of exposure (module power output degradation over time, module and balance of system failures over time, and dirt accumulation), and alternative operations/maintenance policies (timing and quantity of modules to be replaced due to failure or degradation below certain performance levels, module cleaning frequency, and balance of system operations/maintenance alternatives) to system performance, cost, and value over the photovoltaic power plant's operating lifetime. When coupled with an economic model for electric utilities, LCP provides a consistent basis for describing and comparing alternative utility grid connected photovoltaic power system designs and operating strategies. The LCP model is currently being used by the Photovoltaic Technology Development and Applications Lead Center and Low Cost Solar Array Projects at the Jet Propulsion Laboratory for photovoltaic system evaluations. These evaluations include identifying reasonable operations, maintenance and replacement strategies for a range of photovoltaic system and module designs; performing parametric studies of the effect of alternative degradation rates, failure rates, and cleaning policies on system technical and economic performance; calculating system and subsystem breakeven costs; and investigating the impact of regional differences on performance, cost, value, and system design preference