Impact of tropical desert maritime climate on the performance of a PV grid-connected power plant

This paper provides experimental results on the performance of a grid-connected PV power plant operating under dusty, desert maritime climate conditions using data from the first installation of its kind in Djibouti. The first 4 years of operation were evaluated in terms of IEC 61724 measures, and the impact of climate factors was estimated using a novel combination of analysis techniques. The monthly average daily array yield and final yield were 5.1 kWh/kWp and 4.7 kWh/kWp, respectively. The average performance ratio for respective PV arrays and the global grid-connected system were 90% and 84%, corresponding to monthly average daily PV module and system efficiencies of 12.68% and 11.75%. The seasonal variation in PV module efficiency was found to follow a funnel-shape with a sharp minimum centred on July. The impact of ambient temperature and soiling-induced losses were evaluated, revealing a reduction in the performance ratio by 0.7% for each 1 °C rise in daily ambient temperature. Losses due to soiling varied from 0.03% following rainfall events, to 14.23% during dry dusty periods. Finally, to maintain the modules performances losses less than 5%, a cleaning schedule is recommended every two weeks.