Astou Sarr’s research while affiliated with Cheikh Anta Diop University and other places

This study provides a climatological assessment of wind resources in Chad using 100-m wind data from the ERA5 reanalysis. The results highlight spatio-temporal variations in wind potential, Enabling the identification of climate zones suitable for wind farm development. Wind speeds range from 1.5 to 11 m/s, with increasing gradients from south to north. Maximum wind speeds are observed between autumn and spring, particularly from October to April, while minimum speeds, below 5 m/s, occur during the wet season. A distinct diurnal cycle is noted, with nighttime wind speeds averaging 26% higher than daytime speeds. Winds predominantly blow in favorable directions, primarily toward the northeast. The study indicates that almost the entire northern region of Chad (north of 15°N latitude) is particularly favorable for wind farm installations, except for areas around the Tibesti mountain range, where wind speeds remain low due to the presence of a permanent anticyclone. Three zones are identified as particularly promising: the region around Faya, the far northeastern part of the country, and the area around Amjarass. Additionally, long-term analysis reveals a slight decrease in 100-m wind speeds, possibly linked to the increased frequency of La Niña events over the past decade. In conclusion, this study provides a comprehensive assessment of Chad's wind potential, emphasizing that the most suitable areas are located between the Saharan and Sahelian zones.

This study aims to evaluate the contribution of mobile solar panels at the Sakal solar plant in Senegal. The PVsyst model was used to simulate energy production, taking into account both fixed and mobile panel configurations. Initially, the PVsyst model was pre-validated for power plant configurations equipped with both fixed panels (Bokhol) and mobile panels (Sakal), demonstrating correlation coefficients exceeding 0.9. The study's results show that using mobile panels at Sakal increases energy production by over 25% compared to fixed panels. This technology proves particularly efficient during the winter and spring, leading to an increase of over 30%, while a lesser improvement of approximately 14% is observed during the rainy season. The study also emphasizes that solar trackers generate a surplus of over 50% during the early morning hours (between 8 AM and 10 AM) and in the late afternoon (between 4 PM and 5 PM). Furthermore, by categorizing production days, increases of approximately 31%, 26%, and 15% are observed respectively for maximum, standard and minimum days of energy production at Sakal. Finally, this study clearly shows that solar trackers are effective and have a positive impact on increasing solar energy production in the Sahel region.

The objective of this study is to evaluate the clouds seasonal occurrence characteristics, and to estimate their impact on solar radiation in Mbour, Senegal, West Africa. Here, we use datasets from various sources including: i) observations from the Clouds and Earth’s Radiant Energy System satellite sensors, ii) in situ shortwave radiation measurement obtained from the Mbour station, and iii) the outgoing longwave radiation (OLR) obtained from the National Centers for Environmental Prediction reanalysis data. Results show a marked seasonality, associated with high spatial variation in terms of cloud occurrence over Senegal. The maximum cloud occurrences are observed during the wet summer season (June–October), whilst the minimum cloud occurrences are recorded during the long-dry season from November to May. During the monsoon season the cloud activity becomes more intense with a total cloud cover of about 80%, a cloud optical depth of around 7, and a high convective activity illustrated by a low OLR (below 240 W/m2). Likewise, across Senegal a strong north-south gradient of the cloud characteristics is observed. Based on quantitative comparison between cloud occurrence and radiation measurement, results show an important seasonal impact on available solar potential in Mbour. Conversely to the cloud occurrence, the maximum of both direct normal and global solar potentials is recorded during the dry season, coinciding with the period with clean sky. An investigation of the cloud influence on solar radiation on selected study cases indicates a decrease of 60% (80%) for the total (direct normal) radiation during the peak of the summer monsoon season.

The main objective of this study is to evaluate the seasonal performance of 20 MW solar power plants in Senegal. The analysis revealed notable seasonal variations in the performance of all stations. The most significant yields are recorded in spring, autumn and winter, with values ranging from 5 to 7.51 kWh/kWp/day for the reference yield and 4.02 to 7.58 kWh/kWp/day for the final yield. These fluctuations are associated with intense solar activity during the dry season and clear skies, indicating peak production. Conversely, minimum values are recorded during the rainy season from June to September, with a final yield of 3.86 kWh/kW/day due to dust, clouds and high temperatures. The performance ratio analysis shows seasonal dynamics throughout the year with rates ranging from 77.40% to 95.79%, reinforcing reliability and optimal utilization of installed capacity. The results of the capacity factor vary significantly, with March, April, May, and sometimes October standing out as periods of optimal performance, with 16% for Kahone, 16% for Bokhol, 18% for Malicounda and 23% for Sakal. Total losses from solar power plants show similar seasonal trends standing out for high loss levels from June to July, reaching up to 3.35 kWh/kWp/day in June. However, using solar trackers at Sakal has increased production by up to 25%, demonstrating the operational stability of this innovative technology compared with the plants fixed panel. Finally, comparing these results with international studies confirms the outstanding efficiency of Senegalese solar power plants, other installations around the world.

This study aims to evaluate the seasonal performance of six solar power plants in Senegal. Four of them, located in Bokhol, Sakal, Malicounda, and Kahone, have photovoltaic panels with a capacity of 20 MW, while the remaining two plants in TenMerina and Mekhe have panels with a capacity of 30 MW. To achieve this goal, the study real production data and conducted simulations using three commonly used models: RETScreen, PVGIS, and PVsyst. The analysis of field data clearly shows a significant seasonal variation in energy production, with the highest values occurring during the spring months, from March to May. The rainy season results in the lowest production levels, with the weakest output observed in September. This seasonal fluctuation is due to the presence of clouds and dust, which reduce the amount of solar radiation reaching the panels and therefore decrease the plant's production. Additionally, using movable solar panels at the Sakal plant leads to an excess production of more than 19% compared to the other 20 MW plants that use fixed panels. Subsequently, the study used RETScreen, PVGIS, and PVsyst models to simulate the plant's seasonal production. The results show that the models effectively simulate the seasonal production variations of each plant. PVGIS and PVsyst provide more accurate results, with correlation coefficients higher than 0.9, while RETScreen simulates production with a coefficient of approximately 0.7. Furthermore, PVGIS and PVsyst have an additional advantage over RETScreen as they consider mobile solar panels similar to those used at the Sakal plant. Finally, statistical indicators reveal that the PVsyst model performs better than the others in accurately simulating the seasonal production of both fixed and mobile solar power plants in Sahelian environments.

The study presented in this article focuses on the temporal dynamics of wind energy production at the Taïba Ndiaye wind farm in Senegal, with a capacity of 158.7 MW. The monthly and seasonal distribution of production shows a strong trend, with maximums recorded between December and May (winter and spring) at around 1800 MWh, and minimums between July and November (summer and autumn) with production below 500 MWh. The diurnal cycle representation exhibits variation with a marked cycle, particularly between November and April. Night-time production is higher than daytime production by more than 43%. The effects of 100-m wind on the farm production are also analysed and show a positive correlation between wind speed and production throughout the year. Production peaks observed in winter and spring are caused by strong winds (approximately 8.5 m/s), while the lowest levels recorded during the summer season are due to weather conditions characterized by weak winds (less than 4 m/s). Similarly, optimal wind directions are observed in winter and spring, periods of maximum production, when the winds blow between the northwest and northeast.

The study presented in this article focuses on the temporal dynamics of wind energy production at the Taïba Ndiaye wind farm in Senegal. The monthly and seasonal distribution of production shows a strong trend, with maximums recorded between December and May (winter and spring), and minimums between July and November (summer and autumn). The diurnal cycle representation exhibits variation with a marked cycle, particularly between November and April. Night-time production is higher than daytime production by more than 43%. The effects of 100-meter wind on the farm production are also analysed and show a positive correlation between wind speed and production throughout the year. Production peaks observed in winter and spring are caused by strong winds, while the lowest levels recorded during the summer season are due to weather conditions characterized by weak winds. Similarly, optimal wind directions are observed in winter and spring, periods of maximum production, when the winds blow between the northwest and northeast.