Performance trends in grid-connected photovoltaic systems for public and industrial use in Japan

Photovoltaic (PV) systems have become popular globally as an important candidate in the establishment of low-carbon electrical and civil systems. Since the early 1990s, globally, many PV systems have been installed, and their performance parameters such as annual yield, performance ratio, and system losses have been monitored in order to understand their basic characteristics; these data also help in the development of these systems and in analyzing their reliability. In Japan, the performance of residential PV systems was evaluated and reported. However, these evaluations were carried out using older systems, and the current status and the performance trend for each installation year have not been sufficiently evaluated and discussed. Therefore, this report aims to provide a macroscopic evaluation of the performance trends of PV systems by using the monitoring data of systems that were installed between the year 2000 and the year 2007. As a result of the evaluation, we have concluded that the performance ratio of these systems improved to an average of 0.72 until fiscal year 2000 and to 0.78 after fiscal year 2001. For investigating the factors behind this increase in performance ratio, we have focused on characteristics of the actual system capacity (capacity of each PV module measured at the point of shipment) and inverter efficiency. Copyright (C) 2010 John Wiley & Sons, Ltd.