Fig. 8 shows the monthly variation of daily average array yield, reference yield and system yield respectively. The daily average reference yield is directly proportional to the daily average insola- tion. It varies from a minimum of 4.6 h=d in January to a maximum of 7.15 h=d in October. As seen in Fig. 8, the daily average array yield and system yield follow the trend of reference yield. The daily average array yield and system yield vary from a minimum of
3.05 h=d and 2.95 h=d in January to a maximum of 5.07 h=d and
4.94 h=d in October, respectively. For all months of the monitoring period, there is a difference between average array yield and sys- tem yield. This difference was expected due to DC/AC conversion losses produced in the inverter