Chapter IIE-3 - Performance, Reliability, and User Experience

Abstract

Various derived parameters related to the system's energy balance and performance can be calculated from the recorded monitoring data using sums, averages, and ratios over reporting periods such as days, months, or years. The irradiation quantities are calculated from the recorded irradiance. The electrical energy quantities are calculated from their corresponding measured power parameters over the reporting period. For the comparison of PV systems, normalized performance indicators are used: for example, energy yields, efficiencies, and performance ratio. For the wide dissemination of PV technology, the results of long-term performance and reliability of PV systems are important. Financing schemes for PV such as fed-in tariffs require sound figures about real energy yields and performance data. Performance data from 309 grid-connected PV systems in 14 countries are exported from the Performance Database of International Energy Agency and 993 annual performance data are presented for operational years between 1989 and 2002. Monthly input data come from different research and demonstration program in each of the countries, whereas the quality of the collected data depends on the level of monitoring, the kind of data acquisition system used, the availability of the data, the conditions of the program, and the reliability of the data source.