According to data published by the Ministry of Economy, Trade and Industry (METI), the number of residential PV system has been rapidly increasing in recent years, and it reached 1.9 million at the end of March 2015. However, field performance of PV systems has still not been fully evaluated. This paper presents the performance results of more than four thousand residential PV systems with those obtained from 140 thousand measurement data. The result shows that annual performance ratio (PR) has been gradually improved from 0.74 in 2004 to 0.83 in 2013. The performance of newly installed system has been improved. Systems installed in 2012 achieved higher PR in the first year’s operation than systems installed before 2004 by more than 10%. For the 80 systems installed before 2004, the average annual PR was dropped from 0.755 to 0.711, over the period of a year after the installation to 2013, showed an average annual decrease of 0.6%.

View full abstract