In order to have a clear view of the PV plant performances, per- formances of two arrays (array 1 and array 17) from the Sheikh Zayed solar PV plant are compared. Indeed, the array 1 and array 17 are comprised by PV modules from two technologies: micro- morph silicon and amorphous silicon respectively. The array 17 as already mentioned in Table 3, consists of 1458 amorphous sili- con PV modules with the same rated power (420 Wp ) each of them. Four modules are connected in series, two series connection are connected in parallel to form a circuit and three circuits are con- nected in parallel to create one string. Seven combiner boxes are used to combine groups of 8, 9 or 12 PV module strings. The annual average of performance indices of the two subsystems over the monitored period from October 1, 2014 until August 31, 2015 are summarized in Table 8. Array 17 has a daily average array yield, DC performance ratio and capacity factor (4.79 h=d, 75.25% and 19.54% respectively) higher than those of array 1 (4.38 h=d, 67.99% and 17.75% respectively) and therefore has shown better performances during the monitoring period. Regarding losses, the daily average array capture losses and miscellaneous losses of the array 1 (2.02 h=d and 1.86 h=d) are higher than those of array 17 (1.58 h=d and 1.47 h=d). As expected, the daily average thermal capture losses of array 1 (0.16 h=d) is higher than those of array 17 (0.11 h=d) due to the difference between temperature coefficients (Table 2). These results show that the contribution of thermal cap- ture losses on global array capture losses is insignificant compared to the contribution of the miscellaneous capture losses for the two arrays under study, as shown in Table 8. The performance of Array 17 is higher than that of array 1. This is because array 1 presents capture losses (thermal and miscellaneous capture losses) greater than the array 17. There are many causes to the miscellaneous capture losses, such as accumulation of dust, modules aging effect on performance, Joule losses in wiring and diodes, and shading. They can quantify the losses, but however without specifying their exact nature. This gap between the performance of the two arrays is partly due to the difference between the two technologies (array 1 in micromorph and array 17 in amorphous). Furthermore, the PV modules of all arrays are cleaned during a period of 10 days. The cleaning cycle starts from the array 1 and ends at the array 17. PV modules of each of the arrays 1 and 17 are not always in the same conditions. To be more specific, we suggest making an indi- vidualized diagnosis of different modules of all arrays.