Evaluating the reliability and availability of photovoltaic systems

Abstract

SOLREL, a new reliability/availability simulation model, incor porates design, reliability, cost, and maintenance information to predict annual maintenance cost and energy production for photovoltaic [PV] power systems. SOLREL considers failures, lost production, and both scheduled and unscheduled mainte nance. Combined with initial cost and operating cost informa tion, the model predicts levelized cost per kWh. It gives photovoltaic system designers a way to evaluate design trade- offs and minimize life-cycle energy cost.

Large terrestrial photovoltaic power systems (over 50 kWp) are a recent development. Thus, failure rate, repair time, and cost data are lacking for many subsystems and components. In spite of this, reliability/availability models can still aid in design decisions by allowing designers to estimate changes in life-cycle energy costs for alternative subsystems and con figurations. As more test and field data become available, the models can be made more detailed and more accurate. At present, their principal value is to emphasize reliability and maintainability early in system design, with resulting im provements in component selection and subsystem design.