Abstract This paper presents the performance evaluation and analysis of the first large-scale solar photovoltaic plant in Mauritania. The plant has a total capacity of 15 MW p and was installed in Nouakchott. The plant is composed of seventeen arrays connected to inverters and the energy delivered is supplied to the 33 kV electricity grid through nine transformers. Monitoring data from the photovoltaic plant was used to evaluate performance indices such as reference yield, array yield, system yield, DC performance ratio, capacity factor, array capture losses, miscellaneous capture losses and thermal capture losses. The comparison between the performances of two photovoltaic arrays of the photovoltaic plant was performed and the results of this study were compared with other systems installed in other countries. The results show that the photovoltaic plant performances depend on both insolation and environmental conditions. Comparison results show that performance may be different from one array to another from the PV plant. In addition, the analysis shows that the Sheikh Zayed plant exhibit high losses compared to other photovoltaic systems installed in other locations.