Field experience with large-scale implementation of domestic PV systems and with large PV systems on buildings in Japan

Under the auspices of the New Sunshine Program and continuous R&D programs by the New Energy Development and Industrial Technology Organization (NEDO), the authors have been implementing a measurement and evaluation program for photovoltaic (PV) systems since the fiscal year 1997. In this program, a total of 100 residential PV systems, equipped with special data acquisition systems, have been set up over seven years. The purpose of this study was to clarify the operating performance of the grid-connected PV systems on the rooftops of residential houses in Japan and to develop a simulation methodology in order to estimate the electricity generation and costs in the actual housing environment. The validity of the simulation methodology was assessed by using the actually monitored data from some hundreds residential PV systems. Simulation results were also used to optimize the PV system design as well as to diagnose their operating conditions. The mean value of the final annual yield was around 1000 h; 975 h in 2000, 982 It in 2001 and 975 h in 2002, and the mean value of the performance ratio was over 70%; 73.3% in 2000, 71.8% in 2001 and 72.5% in 2001. Copyright (C) 2004 John Wiley Sons, Ltd.