Experimental Evaluation of the Performance Degradation of a Solar PV Plant Operating in a Sahelian Climate

Niger, a Sahelian country, is known for its extreme climatic conditions and its wealth of solar deposits. In Niger, the average duration of sunshine is 8.5 hours per day and its average level is estimated at about 5 to 7 kW/m² per day. However, the rate of access to electricity in Niger remains very low. To address this problem, a 7MW solar photovoltaic power plant has been built by the authorities in the town of Malbaza (13°58.54 N and 13°58.54 E). It has a capacity of 7 MW and is composed of monocrystalline photovoltaic solar panels. In this study, we propose a method for analysing the degradation of a solar photovoltaic power plant under its operating conditions. The study will help to assess the performance and efficiency of PV systems installed in this geographical area. For this study, we use annual energy production data, recorded at the site, from 2019 to 2021. The method is based on the performance ratio values measured during these three years of operation. An hourly IR energy production index was introduced to study the degradation and reliability of the system. The performance ratio values obtained from the measurements in 2019, 2020 and 2021 are 73.22, 72.73 and 70.84 respectively; the calculated hourly energy production index values are 0.921, 0.914 and 0.891 respectively. The PVsyst software was used to estimate the value of the performance ratio. The value obtained is 79.50%. Thus, a degradation of 1% per year over the three years of operation is estimated. Finally, a comparison was made with other studies.