Photovoltaic power potential in West Africa using long-term satellite data

This paper addresses long-term historical changes in solar irradiance in West Africa (3 to 20 degrees N and 20 degrees W to 16 degrees E) and the implications for photovoltaic systems. Here, we use satellite irradiance (Surface Solar Radiation Data Set - Heliosat, Edition 2.1 - SARAH-2.1) and temperature data from a reanalysis (ERA5) to derive photovoltaic yields. Based on 35 years of data (1983-2017), the temporal and regional variability as well as long-term trends in global and direct horizontal irradiance are analyzed. Furthermore, a detailed time series analysis is undertaken at four locations. According to the high spatial resolution SARAH-2.1 data record (0.05 degrees x 0.05 degrees), solar irradiance is largest (up to a 300Wm(-2) daily average) in the Sahara and the Sahel zone with a positive trend (up to 5 W m(-2) per decade) and a lower temporal variability (< 75 W m(-2) between 1983 and 2017 for daily averages). In contrast, the solar irradiance is lower in southern West Africa (between 200 W m-(2) and 250 W m(-2)) with a negative trend (up to 5 W m 2 per decade) and a higher temporal variability (up to 150 W m(-2)). The positive trend in the north is mostly connected to the dry season, whereas the negative trend in the south occurs during the wet season. Both trends show 95% significance. Photovoltaic (PV) yields show a strong meridional gradient with the lowest values of around 4 kWh kWp(-1) in southern West Africa and values of more than 5.5 kWh kWp(-1) in the Sahara and Sahel zone.